Design Document - Tensioned Building Construction

Design Document

For

Project Tensioned Building Construction

Submitted by:

Luke SkellyRob Lewis

Dani Jackson

Diana C. Etheridge

Dr. Matthew Gordon

05/29/15

Change History Page

10/02/14 Original document created11/10/14 Changes made to document prior to End of Quarter Design Review01/07/15 Changes made to document to incorporate winter interterm work02/04/15 Changes made to document prior to Proof of Concept Design Review03/07/15 Additional analysis including the floor, brackets, and rope and changes made to

reflect Dr. DeLyser’s comments.05/09/15 Changes made to document for resizing of structure

Tensioned Building Construction 05/29/2015 Page 1 of 106

Table of Contents1. INTRODUCTION................................................................................................................3

1.1 Purpose..................................................................................................................................31.2 Scope.....................................................................................................................................41.3 Definitions, Abbreviations, Acronyms.....................................................................................4

2. APPLICABLE DOCUMENTS AND REFERENCES.....................................................................42.1 Legal Documents....................................................................................................................42.2 Project Documents.................................................................................................................4

3. ASSUMPTIONS AND DEPENDENCIES.................................................................................4

4. DESIGN OVERVIEW AND SYSTEM DESCRIPTION................................................................54.1 Top Level Context Diagram.....................................................................................................54.2 Functional Decomposition......................................................................................................74.3 Systems Diagram....................................................................................................................84.4 Functional Traceability Analysis............................................................................................104.5 System Traceability Analysis.................................................................................................114.6 System-Level Design Alternatives.........................................................................................124.7 Budget Overview..................................................................................................................164.8 Limiting Requirements..........................................................................................................184.9 Key Technical Issues..............................................................................................................194.10 Impact on Society...............................................................................................................204.11 Fabrication Plan..................................................................................................................214.12 Project Location..................................................................................................................22

5. SUBSYSTEM/MODULE DESCRIPTION...............................................................................255.1 Foundation System...............................................................................................................25

5.1.1 Design Alternatives...............................................................................................................255.1.2 Selection of Primary Design..................................................................................................27

5.2 Tension System.....................................................................................................................325.2.1 Design Alternatives...............................................................................................................325.2.2 Selection for Primary Design................................................................................................33

5.3 Structure System..................................................................................................................345.3.1 Structure Design Alternatives...............................................................................................345.3.2 Key Technical Issues.............................................................................................................355.3.3 Selection for Primary Design................................................................................................42

5.4 Enclosure System..................................................................................................................435.4.1 Enclosure Design Alternatives..............................................................................................435.4.2 Key Technical Issues.............................................................................................................445.4.3 Selection for Primary Design................................................................................................45

6. REFERENCES...................................................................................................................46

7. APPENDICES...................................................................................................................48


1. INTRODUCTION

1.1 Purpose

Structures are necessary all over the world from suburban homes to office buildings to makeshift huts in the desert. In many cases, expense and speed are two very important qualities that must be taken into consideration for these structures. This brings a need for a simple building that will maintain stability in various conditions and can be easily built.

Because this is such a widespread problem in the world, many organizations have systems already in place. The UNHCR (United Nations High Commissioner for Refugees) commonly uses canvas tents when aiding refugees and internally displaced people [1]. While these tents are inexpensive with only one unit costing $500 [2], living in one provides very little dignity to the user. Despite over millions of internally displaced people and refugees, there are very few international standards when it comes to humanitarian aid, specifically with the use of temporary structures. There are some standards on general fire safety, structural strength of tent fabrics and specifications of structures; however, these do not provide much adequate guidance when it comes to environmental risks. Tents are also very inefficient in terms of insulation. With just a thin layer of fabric between the interior and the environment, the tents do not provide adequate shelter to the user. Heat is lost through thermal conduction through the tent fabric, infiltration loss through leaks and holes, and heat transfer to the ground. With such limited resources at their disposal, fuel is often an extravagance that is neither affordable nor accessible. With fuel unavailable, alternatives must be considered to keep the interior at a livable temperature. One such alternative that should be considered is providing insulation within the structure [2].

Various patents have been granted describing a temporary structure that is more stable than a tent. One such example was a structure that operates using tensioned cables as the main framework with the cables tightened using a scissor frame design [3]. This design however can be unstable and can be complicated to assemble. A building with a tensioned cable frame that is simple to assemble is ideal. The design concept for this building, which utilizes turnbuckles to tension the frame system was created and patented by Diana Etheridge [4].

The purpose of this section is to describe the requirements to be met by the Tensioned Building being designed for Diana Etheridge by the Tensioned Building Construction design team. This document is intended for Diana Etheridge. It is also intended for the members of the Engineering Design Class, the instructor, and Dr. Gordon, the faculty consultant for the project.The motivation for this projects stems from Diana Etheridge’s patent for a building construction with an integrated tensioned support system [4]. This system allows for the rapid and inexpensive construction of conventionally appearing buildings in areas with limited resources (both economically and physically), limited access, or both.


1.2 Scope

This document describes the design and subsystems of the Tensioned Building. The system has been divided into 5 subsystems: the foundation system, the tension system, the structural system, the enclosure system, and the insulation system. This document will describe the conditions that are imposed on each system and provide a basis for the expected conditions that this system will be able to support.

1.3 Definitions, Abbreviations, Acronyms

Compressive strength – the capacity of a material or structure to withstand loads tending to reduce size; can be measured by plotting applied force against deformation.

PVC – polyvinyl chloride

R Value – a measure of thermal resistance used in building and construction industries.

Flexural strength - a material’s ability to resist deformation due to load.

Live load – temporary or moving load which includes considerations such as impact, momentum, vibration, slosh dynamics of fluids and material fatigue.

2. APPLICABLE DOCUMENTS AND REFERENCES

2.1 Legal Documents

Building Construction for Tensioned Support System patent [4].

Wind or Fire Protection System for Structures patent application [5].

2.2 Project Documents

Tensioned Building Construction RFP [6].

Requirements document for Tensioned Building Construction design project [7].

3. ASSUMPTIONS AND DEPENDENCIES

This design is operating under the assumption that the structure will not be operating within an extreme environment (i.e. sand, swamp, snow).

The tensioned system will be operated using turn buckles [4].


The tensioned system will be attached to the foundation using hooks and rings [4].

4. DESIGN OVERVIEW AND SYSTEM DESCRIPTION

4.1 Top Level Context Diagram

A Top Level Context Diagram, shown in Figure 1, can be used to better understand the system development process. All of the inputs are evaluated based on what is desired of the system. The customer plays an important role in this because it is being designed for use by the customer in the long run. The system must be easily assembled and transported so that it may easily be distributed to the customer. It must also be inexpensive to manufacture to help keep costs down and enable more customers to purchase the product. While function is necessary for the design to work properly, it must also be aesthetically pleasing for the enjoyment of the customer. The intended use of the system is for everything from manufactured homes and offices, temporary shelters, and to military structures.

There are also business needs that the system must meet. Because of how easily assembled and transported the system is, it will be more accessible for use in remote locations. From a business standpoint, this would mean it is possible for more people to use the system, and by making simple, effective, and easy to build shelter systems it is possible to provide shelter to those who can’t afford it.

There aren’t many controls that change how we have to achieve the desired system specified in the inputs. No standards, both nationally and internationally, have been found that would influence the system. There is a huge window of opportunity for the system though, because there is a global need for a low cost and easy to build shelter. The enablers include those individuals and organizations that are directly involved in the design of the system. This includes subject matter experts like Mrs. Diana Etheridge with Flex systems, and John Buckley, who can provide insight into the details of the entire manufacturing process. This also includes Dr. Matthew Gordon, the project advisor, who advises on the engineering analysis and overall project ideas. The University of Denver Engineering Design Team is directly responsible for the design and prototyping of the system. The design team will use all of the above information to develop and implement a design for the Tensioned Building Construction system.


Controls-Windows of Opportunity Need for low cost, easy to build structures across the world

Inputs-Customer Needs Easily assembled/transported Inexpensive to manufacture Aesthetically pleasing/functional-Intended Use Manufactured homes/offices & temporary shelters Military structures-Business Needs Simple, effective, and easy to build structures for sheltering displaced families Accessible in remote locations

SystemDevelopment

Process

Outputs-Implemented Design Tensioned Building Construction-Complete Design Documentation

(includes requirements, test reports, schematics, drawings, process instructions, V&V documentation)

Enablers-Subject Matter Experts Mrs. Etheridge (Flexsystems) John Buckley (Manufacturing) Dr. Matthew Gordon (Analysis)-University of Denver Engineering Design Team-Conceptual Prototypes

Figure 1. Top Level Context Diagram


4.2 Functional Decomposition

Figure 2, shown below, is the system functional decomposition for the tensioned building structure. Each functional block consists of the function that the system will have and the requirements that the function will fulfill in brackets. The entire system has been divided into 5 separate subsystems: the foundation, the tension system, the structure, the insulation, and the enclosure. The enclosure subsystem works with the insulation system to ensure that the structure is insulated and protected from environmental factors. These environmental factors include precipitation and wind. The enclosure system consists of two main parts with an exterior enclosure material and an interior enclosure material. These two materials are connected to either side of the insulation section. The tension subsystem works with the foundation to maintain stability within the structure. This is done by connecting the tensioned cables directly to the concrete foundational blocks. The tensioned cables within the tension subsystem must be easily and quickly tensioned, this means that it should not require a large number of tools or strength to tension the system. One main function of this design is ease of assembly and transportation of the entire system. This system should be able to be shipped anywhere in the world. The system should also not require extensive engineering knowledge in order to assemble it. All parts will be fabricated and require few tools to assemble them.

Figure 2. Functional Decomposition


Overall System

Enclosure Subsystem

Enclosure protects interior from environment (i.e.

snow, rain, sun)[1.1, 5.1, 5.2, 5.3, 6.1]

Tensioned Subsystem and Foundation

Ability to be Tensioned by non-engineer within 90

minutes[3.2]

Tensioned to anchor blocks to maintain stability

[2.1, 2.2, 3.1, 4.1]

Assembly

Portable/easily shipped[1.4, 1.5]

Construction doesn't require any engineering

knowledge[1.5, 1.6]

Inexpensive Living Space[1.2, 1.4, 1.7]

4.3 Systems Diagram

The systems diagram in Figure 3 provides a detailed cross section view of the subsystems which are integrated into the overall system. Each subsystem is shown in the cross section view and labeled in the provided legend. The structure subsystem is shown by blue lines, which represent the frame of the building. Running in between all of those blue lines is the tension subsystem, shown with a single solid green line. This green line represents the path of the cable used to tension the entire building. The red zigzag hatching shows the location of the insulation subsystem. All of the insulation will be placed above the ceiling and in between the interior and exterior walls of the enclosure subsystem, shown as the layer of black dots around frame. The materials used for the inner and outer walls will differ, as explained in section 5.3, but because each wall encloses the insulation and frame of the building they are part of the same subsystem. The concrete blocks and the floor of the building are both part of the foundation subsystem, because both are supporting the structure and enclosure subsystems. The concrete blocks must be secured underground because they are supporting the entire load of the tension subsystem and the structure. The cross beam in between the inner and outer wall of the structure doesn’t have a cable running through it for tensioning.


Figure 3. Systems Diagram


4.4 Functional Traceability Analysis

The table below creates a direct connection between the functions that were shown in the functional decomposition above (Figure 2), and the requirements as given in the Requirements document. This shows how each requirement ties into a function of the Tensioned Building System. The requirements for the insulation and enclosure subsystems tie directly to the building’s insulation and protection functions. The requirements for the tension, structural, and foundation subsystems tie directly to the building’s ease of tensioning and stability functions. The requirements detailing the shipping dimensions and ease of assembly tie directly to the portability of the structure and the lack of engineering expertise functions. The requirements detailing the cost of the system and the house-like quality tie directly to the inexpensive living space function.

Table 1. Functional Traceability Analysis

Requirements 5.x.xFunction 1.1 1.2 1.3 1.4 1.5 1.6 2.1 2.2 3.1 3.2 4.1 5.1 5.2 5.3

Protection from environment X X X XEasily/Quickly tensioned XAnchor blocks for stability X X X XPortable X XInexpensive Living Space X X X


4.5 System Traceability Analysis

The table below depicts the system traceability analysis, which shows which requirements are connected to each Subsystem. The first section of requirements (1.1-1.7) describes general requirements that the entire system must conform to. Each subsequent section of requirements refers to a specific subsystem and can clearly be seen in the table below. The last section of requirements (7.1 and 7.2) refers to second-tier requirements or requirements that are not necessary, and should only be implemented if time and money allow.

Table 2.System Traceability Analysis

Requirements

System1.1

1.2

1.3

1.4

1.5

1.6

1.7

2.1

2.2

3.1

3.2

4.1

5.1

5.2

5.3

Foundational X X X X X X X X XTensioning X X X X X X X X XStructural X X X X X X X XEnclosure X X X X X X X X X X


4.6 System-Level Design Alternatives

Designs can be modified on a system level by adjusting the size of the overall structure. This can be done to either increase functionality or decrease cost. Different sizes of this system will result in different organizations of the structural beams. Because longer beams will buckle under large loads, as the length of the overall system is increased, the number of cross sectional beams will need to be increased. This can be seen in the Figures 5 and 6 below. The standard size of the structure, which was used for all analysis of the structure, is seen in Figure 4. This structure requires one cross-sectional beam to be added in the center of the structure. This is done to support the weight of the roof. If a 30’ long building was desired by the customer then an additional cross-sectional beam within the interior of the structure would be required. Cost of construction per square foot will be given to give different size possibilities.

Figure 4: 13’ Structural Current Design


Figure 5: 22’ Structure Design


Figure 6. 20' Structural Design


4.7 Budget Overview


The preliminary budget for the design process was used as tool to do quick cost analysis. This was done by splitting up the budget by sub-system, and then inserting separate options with different units and prices to determine quantities and total cost. This allows for different options to be swapped in and out in order to see how different design alternatives will affect the budget. The source and relevant specs were also included for easy reference. The functionality of the budget was crucial when analyzing design alternatives to ensure that the options chosen based on the quantitative ranking scale are not going to put the design over budget. The budget does not take into account donated materials obtained at this point in time. As more donated materials are obtained, the cost will be subtracted from the working budget but will still be included in the overall cost for reproduction.


Figure 8. Budget Overview


4.8 Limiting Requirements

The most limiting requirements within this project are requirements 5.1.2 and 5.1.4 and the 5.5.0 section of requirements. Requirement 5.1.2 constricts the budget to $2000.00. This requirement has severely limited the materials that are available for this project, and has made acquiring some necessary components of this project difficult. There were many times when the ideal material was not available for use due to limited expenses. An example of this is using aluminum to manufacture brackets, when a different material such as steel would be stronger and more stable. The manufacture of these brackets was also impacted by the limited budget. Outsourcing the manufacture of the brackets would increase the quality of the product; however, there is no room in the budget for this. This means that all brackets must be manufactured in-house.

Requirement 5.1.3 constricts the size of the materials when shipped. This is also done to restrict transportation costs. This requirement made a large impact on the weight and size of the materials that were chosen. Similar to the limitations with the cost, lighter materials were chosen over heavy materials such as aluminum over steel.

The requirements stated in section 5.5.0 of the Requirements document dictate the enclosure that surrounds the structure. Requiring a door and window that are separate from the enclosure material (still connected to the enclosure but not the same material) has restricted the budget. Having the door and window be interfacing with the enclosure material requires more of the budget to be allocated to the enclosure subsystem. The system used to connect the enclosure to the structure required a lot of considerations to be made about the system as a whole. It required deciding how the enclosure would be deployed around the structure, how the enclosure could be maintained in tension around the structure, and how the enclosure would be connected to the floor of the structure.

Overall, these requirements caused many different design alternatives to be considered to follow the requirements, both set by the customer and by the project team.


4.9 Key Technical Issues

The key technical issues of this project are the interfaces between the subsystems and between the components of each subsystem. A good example of this is the brackets which connect the PVC beams within the structural system. These brackets experience the majority of the load and therefore are critical in design and manufacturing. Another example of this is connecting the structural and tension subsystems to the foundational subsystem. The majority of these connections will utilize the setting concrete to hold the subsystems in place. Another key technical issue is connecting the exterior and interior to the structural subsystem. While Silicon will be used to connect the fabric to the PVC, the application will take some skill. Overall these interfaces will need to be closely monitored to ensure that the overall structure is stable.


4.10 Impact on Society

The details of the impact that this design will have on society can be found in Appendix A. This will discuss the following considerations of the design: economic, environmental, social, political, ethical, health and safety, manufacturability and sustainability.


4.11 Fabrication Plan

The fabrication plan, which details the fabrication of each of the parts of this design, can be found in Appendix D.


4.12 Project Location

For this project, a fairly large building location is required. Finding a location on campus was the ideal case, because it would provide convenient access for the design team. Unfortunately, due to the size of the structure and the digging involved for building the foundation subsystem, no suitable location on campus was available. Alternative locations for building the project were considered, and after speaking with John Buckley, the machine shop manager, he recommended contacting Justin Wiley with the University of Denver Applied Research and Technology Institute (ARTI). ARTI has a location off campus called the East Range, located east of Denver on approximately 130 acres of open range land. Justin put us in contact with the East Range Manager Donald New, and after meeting with him he approved building on the property. An aerial view of the property location relative to Denver is shown in figure 9. Figures 10 and 11 show more specific aerial views of the exact building location.

Figure 9: Building Location relative to Denver, CO.


Figure 10: Aerial view of Building Location on Property.

Figure 11: Aerial view of exact building location on property.


Figure 11 shows the exact building location of the Tensioned Structure System. This location is ideal for building on the ARTI east range property due to the easy access of bringing materials to the location. The location is also chosen since the ground is level and doesn’t require any leveling work to the ground.


5. SUBSYSTEM/MODULE DESCRIPTION

5.1 Foundation System

This subsystem includes the foundational concrete blocks that are below ground, the system of rods that connect the blocks, the J hooks that attach the rope to the blocks, and the base of the floor. The requirements that affect this subsystem are 5.1.3, 5.2.1 and 5.2.2.

5.1.1 Design Alternatives

The location of the anchor blocks was based on which design was the most cost efficient, number of blocks needed in tension, as well as the amount of blocks needed. One key technical issue that arose for the anchor blocks was the connection between the anchor blocks. This includes whether or not the cables tensioning the blocks to each other will be underground and how they’re connected to the foundational system (floor base). The tensioning criteria entails the amount of blocks needed to be in tension, which affects the amount of turnbuckles and tensioning rope needed and accounting for the advantage of having a shared foundation block between the inner and outer wall vertical supports. The different options for the location of anchor blocks varies the amount of blocks needed in tension between 6 and 22 blocks. The ease of implementation criterion entails the amount of anchor blocks placed to provide a base for the structure. From the different design options shown in the table above, there will be 6 to 17 blocks to anchor the structure to the ground. For weighing the importance of each criterion, the cost of constructing the blocks was the most critical criterion due to having a limited budget. The ease of implementation was the second most critical criterion. This is due to the desire to limit the amount of material needed. The amount of blocks in tension was considered, but not very much. This is due to the cost of turnbuckles and tensioning rope being very inexpensive and the ability for the structure to be completely tensioned not being affected very little by the tensioning between the anchor blocks.

The material of the floor base was based on which design was the most cost efficient, compressive strength of the material, and the time required to construct the base.


Table 3. Foundation Design Matrix

When analyzing the most cost effective option, creating a floor base out of wood is almost twice the cost as concrete. Although the concrete is the most cost efficient, the wood would take roughly 12 hours to construct while the concrete would take almost 48 hours due to the concrete having to set and dry for over 24 hours. The compressive strength of the floor base measures the material’s ability to not deform under large loads. The compressive strength for the concrete is 30MPa, whereas wood is only 20MPa at its strongest point and 5MPa at the weakest points. Thus the concrete provides a much greater structural support than wood.

When weighting the importance of the criterion, the cost was the most important. The compressive strength was the second most important criteria due to the floor base’s requirement of supporting at least 1000 pounds of weight. The amount of time required to construct the floor base was not critical to the design, but it was for the building time.


5.1.2 Selection of Primary Design

The selected anchor block layout design was a shared anchor block between inner and outer vertical posts. This design is the most structurally stable since there is no room for movement between the inner and outer supports making the structure as strong as possible. For each primary anchor block there is a secondary anchor block secured to it to increase stability of the overall structure.

Each corner block will hold three vertical posts for the structure. The basic CAD drawing for the concrete portion of the corner block can be seen below.

Figure 12. Corner Foundational Block CAD


Each of these blocks will be interconnected using the ½” polypropylene wire. The following figure shows the connection of each of the primary foundational blocks.

Figure 13. Primary Foundation Blocks with Tension

This is just a simple outline of the foundation. A closer look will show how these pieces are assembled together.


Figure 14. Corner Foundation Block Assembly

This diagram shows how the foundation blocks will be connected. There will be three aluminum joints connected to the primary block. These joints will be connected to the concrete while it is drying so that they are permanently inside. These joints will be submerged into the concrete at least 3 in.


The selected floor base material was concrete. This is due to concrete having much greater compressive strength than wood with only being half the cost of a wood base. The following diagram shows the basic outline of the concrete slab that will act as the floor.

Figure 15. Concrete Slab CAD


The following diagram shows how the concrete flooring will match up with foundational blocks. The above blocks will go into the holes seen in the diagram below. The floor will be level with the ground and occupy 2” of the space below the surface. Then the top of the foundational blocks will be flush with the floor, however there will be a space in the floor for the PVC and tensioning rope. Each foundation block is 1’ deep.

Figure 16. Concrete Slab in relation to Ground


5.2 Tension SystemThis subsystem includes the turnbuckles and rope. The requirements that affect this subsystem are 5.1.3 and 5.3.1.

5.2.1 Design AlternativesTable 4. Tension Design Matrix

The type of turnbuckle chosen was based on cost per turnbuckle, the tensile strength of the turnbuckle’s material, and the working load limit of each type of turnbuckle. The working load limit and material’s tensile strength both account for the strength and durability of the turnbuckle. Size was also considered since it must be capable of fitting inside pipes with diameters less than 6”. This neglects any turnbuckles that require a wrench or other tensioning tool.

The tensile strength of the turnbuckle’s material accounts for the amount of force it can withstand without the material itself deforming or failing. The working load limit measures how many pounds of force the turnbuckle can hold before the possibility of failure. This would be the threaded connection becoming distorted and failing.

When weighting the chosen criterion, the cost was the most critical in the selection process. The working load limit was weighed almost as high as the cost, but not as high due to all the options having a minimum of 400 pounds working load limit. The material tensile strength was weighed the least. This is due to the turnbuckle’s very high probability of failing due to an excess of a working load before failing due to an excess tensile stress on the material itself. This says that the turnbuckle components will become unthreaded before the entire turnbuckle is strained or stretched.

The tensioning rope material chosen to implement in the design was based on the cost, breaking strength, and shipping weight criterion. The cost and shipping weight don’t directly affect the structure, but do affect the budget and requirement 4.1.4 in the requirements document. The breaking strength of the material is the amount of pounds of force it can withstand before encountering the possibility of failure, which is critical for the strength and durability of the structure. Failure in the tensioning rope will result in an inefficient structure and the possibility of additional structural failures.

The cost and breaking strength criterion were both weighted for 2/5th of the overall selection weight. The breaking strength is most critical, but the cost is also substantial since the difference in prices of the materials is up to $800. The price difference inhibited certain materials to be plausible due to budgeting constraints. The shipping weight was taken into account; however, it wouldn’t inhibit any materials from being able to be used.


5.2.2 Selection for Primary Design

For the turnbuckles, the galvanized steel hook and eye turnbuckle was chosen to implement in the design. The hook and eye turnbuckle cost only $2.90 each, which is 1/5th the price of the second cheapest option. It has a working load limit of 700 pounds. Although it cant support as large of a load as the J-hook lever load binder turnbuckle, it still provides a sufficient safety factor greater than 2.

½” Polypropylene rope was chosen as the tensioning material. The ½” polypropylene was the most cost efficient other than the 3/8” polypropylene rope, but has a 3800 pound breaking strength compared to only 2450 pound breaking strength for the 3/8” rope. This provides the structure with 1350 additional pounds of force until failure, with only a $30 price difference.


5.3 Structure System

This subsystem includes the rods that guide the tensioned rope throughout the system, and the brackets that connect the rods. The requirement that affects this subsystem is 5.4.1.

5.3.1 Structure Design Alternatives

Table 5. Structure Design Matrix

The material chosen to use as the structural support material was based on the cost, yield strength, and shipping weight criterion. The cost criteria is crucial due to desired material being too expensive, such as the 2” aluminum piping being priced at $4024 with an overall budget of half that cost. The compressive strength is the amount of compression the material can withstand before failure. Due to the support structure being in tension, the structural support material is in compression at all times, unless not tensioned. The shipping weight was a chosen criterion due to shipping and packaging constraints.

The cost and compressive strength were weighted the greatest. The cost was weighted high due to specific desired materials being too high in cost. The compressive strength was highly weighted due to structural safety purposes. Since the chosen material will endure most of the environmental forces, it is required to withstand the greatest possible amount of compression when the turnbuckles and rope are fully tensioned. The weight was considered due to shipping purposes.

The brackets connecting the structural support materials selection criterion were cost, yield strength, and shipping weight. There are 38 different brackets implemented into the design consisting of 62.42 feet of tubing for fabrication. The yield strength was chosen as a criterion to ensure structural safely. Failure in the brackets will result in failure of the entire structure. Shipping weight was considered for shipping purposes.

For weighting the criterion, the cost was weighted the greatest due to the price of 56.25 feet of metal tubing. The cost difference of the materials selected to quantitatively choose from was $120 to $800. Since $800 is more than what the budget is capable of allotting, this was a critical criterion. Since the three different selected possible materials are metals, the yield strength for the different material was weighted the same as the shipping weight criterion, which is 1/5th the total weight.


5.3.2 Key Technical Issues

Key technical issues for the structure system consist of the brackets connecting PVC frame pieces together, installation of the door, and installation and support of the windows. For the brackets, 2 ½” pipe will be used so that the 2” PVC can easily fit inside the brackets. A stopper will be created within the circular bracket base so that the PVC sits well inside the bracket. The brackets will be made from aluminum so that the angled pieces can be welded into the correct angles upon fabrication. Stress analysis on each bracket will be done. The brackets have been designed to account for all key technical issues identified.

A doorframe will have to be built to install and support the door for the structure. The doorframe will be constructed out of either wood or metal, whichever is more reasonable in cost and lightweight. One side of the doorframe will be attached to the middle PVC piece on the side of the structure to provide extra support for the door and frame. There are two options for the installation of the windows for the structure. The first option is a floor to ceiling window, which would be supported by the floor, top PVC cross piece, and horizontal pieces on the sides of the window for additional support. The second option is to cut a piece out of the outer wall material and adhesively stick the window frame to the wall directly with the window consisting of a very light weight material such as thin Plexiglas. The second option is preferred; analysis on the amount of stress the walls can hold before failing will be completed.

Figure 12. Joint Locations


Figure 13. Bracket #1

Figure 14. Bracket #2A


Figure 15. Bracket #2B









Figure 21. Hinge Joint

Figures 13.21 are the designs for the different brackets corresponding to the labeled bracket locations in figure 12. Each of the brackets is made out of 2.5” outer diameter metal tubing with an inner diameter of 2.4”. The brackets were constructed so that all 90-degree angle connections are welded together for a greater structural support and the other angle connections are attached using the hinge assembly. The hinged connections are used for ease of fabrication. There are 24 brackets implemented into the design. There are open sides of the brackets to allow access to the turnbuckles located within them. The brackets allow access to the turnbuckles when either fully open or fully closed, which is a difference in length of 4.5”. On the ends of each connection for the brackets before the opening for the turnbuckle access points, there is a small stopper ring inside the tube in order for the PVC to have no movement when connected to the brackets.

Tables 6 and 7 below show the bracket material usage for each bracket (Joint). This includes accounting for every pin, hinge, bolt, nut, washer and foot of aluminum tubing. Table 6 accounts for the length of tube for each bracket in inches and feet and the total tube length used per bracket number. The bottom right is number is the total tubing used in feet for the fabrication of all brackets. The bottom right is the total tubing used for the fabrication of all the joints in feet. Table 7 accounts for the different hardware used in each joint number and the bottom is the total material used for each piece of hardware in all brackets fabricated.


Table 6. Bracket Material Usage

Table 7. Bracket Material Usage


5.3.3 Selection for Primary Design2” PVC was chosen as the structural support material due to affordability and having a

yield strength great enough to ensure structural stability. Aluminum pipe has the greatest compressive strength and would be the most structurally safe, but was too expensive to implement in the design. The 2” PVC is half the price of 3” PVC while having a 55MPa compressive strength, which isn’t much less than the 63MPa compressive strength of the 3” PVC. 1 ½” PVC was cheaper than the 2” PVC by only $75 and has a compressive strength of 42 MPa. Since the structural support material withstands the greatest stress, it was determined more important to pay $75 more for 13MPa more in compressive strength.

309 Stainless Steel was the chosen bracket material for a variety of reasons. It is the substantially most cost efficient material due to our ability to get recycled 309 Stainless Steel for $2 per pound making 65 feet cost only $136. 309 Stainless Steel is also the easiest metal to weld. Since the welding process is the final step in the bracket fabrication process, weaker metals are easier to burn holes in resulting in a loss of materials and time. The stress concentrations on the structure from stress applied on the sides and top of the structure due to heavy winds are on the brackets. The material has a yield strength of 621 MPa, making it the safest material to use.


5.4 Enclosure System

This subsystem includes the material that surrounds the interior, the material that surrounds the exterior, the floor, the windows, the door, and the roof. The requirements that affect this subsystem are 5.5.1, 5.5.2, and 5.5.3.

5.4.1 Enclosure Design Alternatives

Table 8. Enclosure Design Matrix

The outside enclosure material selection criterion was cost, shipping weight, and breaking strength using the grab method. Cost and shipping weight don’t affect structural stability, but are necessary to consider due to budgeting and shipping constraints. The breaking strength is critical since the outside enclosure material will be affected the greatest by environmental conditions. The breaking strength grab method is measured by the amount of pounds of force the material can be pulled before deformation and failure. It’s a more specific way of measuring the yield strength for thin fabrics.

Since all the chosen materials are similar in price and weight varying from $317-$447 and 23lbs-35lbs, which are not substantial differences, the breaking strength was weighted the greatest for the chosen criterion. Cost and weight are each weighted one third the amount of the breaking strength.

The interior enclosure material selection criterion was cost, shipping weight, and breaking strength. It’s the same selection criterion as the outside enclosure material. The interior material doesn’t endure as much force and environmental conditions as the outside enclosure making the weighting of the criterion more on the cost and less on the strength. For the amount of material needed, the price difference in the selection of materials was greater than the outside enclosure material, varying in price by $85. The cost and breaking strength were both weighted at 0.4 and shipping weight at 0.2.


5.4.2 Key Technical IssuesThere are two key technical issues present in the enclosure system. These issues consist of

easily installed connection of the walls to the frame and the installation of the structure’s roof. For connecting the walls to the structure frame, Adhesives will be used to stick the walls to the bottom and side of the base floor of the structure as well as the sides of the PVC that are in contact with the walls. Alternative approaches to this issue that have been researched consist of; creating a sleeve sewing outside walls together to perfectly fit the structure frame and sliding the walls over the structure with connection at the bottom of the floor base or frame. Another approach is connection of walls to the anchor blocks by means of hooks for the connection.

For the roofing installation issue, we have explored possible materials to use for the roof. Tyvek or nylon sheets will be used for the base of the roof if cheaper materials are not readily found. Duro-last Shingle-Ply roofing system will be incorporated on top of the base roof material by means of adhesives to provide waterproof insulation and give it a more home like look. Further analysis will be completed on materials that provide as much insulation and support as Tyvek or nylon with a lower cost.

Table 9. Forces on Walls

Wind Speed = 25 mphPressure = 55 PaForce = 613.162 NWall Area: 11.1484 m^2

A wind speed of 25 mph creates a pressure of 55 Pa. For the wall with the greatest area without supports, which is the end walls, has a wall area of 11.1484 m^2. This is where the wall material will see the greatest forces.

Table 10. Fabric Properties

210 Denier Fabric 70 Denier Fabric

X-Direction (Warp)Y-Direction (Fill)

X-Direction (Warp)

Y-Direction (Fill)

Breaking Strength 200 lb/in. 150 lb/in. 65 lb/in. 55 lb/in.Max Force before Failure: 13.34 KN 5.34 KN 3.47 KN 1.96 KN

The 210 is the exterior wall material and the 70 Denier is the interior wall material. The table shows the breaking strength and max force before failure. The 210 Denier Fabric, since it’s the exterior enclosure material, sees the majority of environmental forces. These numbers say that the wall can safely have up to 5.34 KN of force before failure. This is a greater number than will be seen in the building environment.


5.4.3 Selection for Primary Design70 Denier Ripstop Nylon Fabric was chosen to implement as the interior wall material.

The Litelok nylon fabric has the greatest breaking strength, but is $70 more expensive than the chosen material. Litelok fabric also has a breaking strength two times greater than 70 Denier Fabric, but is not necessary to have a 150 pound breaking strength for the chosen application where 75MPa is sufficient for structural stability. Tyvek is similar in price and strength to 70 Denier Fabric, but is a heavier material, thus 70 Denier Fabric is the most suitable material to use.

210 Denier Double-Wall Ripstop Nylon, Polyester, DMC material was chosen as the outside enclosure material. Although it is the most expensive costing $447.30, its breaking strength is 205 pounds. The material with the second greatest breaking strength, 1.9oz Coated Ripstop Nylon Fabric, is only 115 pounds. Due to durability and the longevity of the structure, the increase in strength outweighed the price difference compared to the other choices. Although 210 Denier Double-Wall Ripstop fabric was chosen, due to the supplier being out of stock of this material since March 25th and is still not in stock the interior enclosure wall material is used for the outside enclosure wall material as well.


6. REFERENCES

[1] UNHCR – UN Refugee Agency Shelter, n.d., “Shelter.” from www.unhcr.org/pages/49c3646cf2.html

[2] Manfield, P and Ashmore, J and Corsellis, T. 2004. “Design of humanitarian tents for use in cold climate” Building and Research Information, 32(5) pp. 368-378

[3] Ziegler, Theodore R. Mechanically deployable expandable and collapsible structure and method for deploying structure. World Shelters, Inc., assignee. Patent 7533498. 19 May 2009. Print.

[4] Etheridge, Diana C. Building Construction with Tensioned Support System. Diana C. Etheridge, assignee. Patent 5,930,971. 3 August 1999. Print.

[5] Etheridge, Diana C. Wind or Fire Protection System for Structures. Diana C. Etheridge, assignee. Patent Application 14/311,634. 23 June 2014. Print.

[6] Etheridge, Diana C. (2014) Request for Proposal. University of Denver’s School of Engineering and Computer Science.

[7] Lewis, Robert, David Dredge, Danielle Jackson, and Luke Skelly. Tensioned Structure System Design Document. 6 October 2014. Print.

[8] www.engineersedge.com/civil-engineering/concrete/floor_slab_stress.htm[9] www.aboutcivil.org/flextural-strength-of-concrete.html[10] Bolin, B., 2006. Race, Class, Ethnicity, and Disaster Vulnerability. In Rodríguez, H.,

Quarantelli, E. L., and Dynes, R. R. (eds.), Handbook of Disaster Research. New York: Springer, pp. 113–129

[11] Enarson, E., Fothergill, A., and Peek, L., 2006. Gender and disaster: foundations and directions. In Rodríguez, H., Quarantelli, E. L., and Dynes, R. R. (eds.), Handbook of Disaster Research. New York: Springer, pp. 130–146

[12] Girard, C., and Peacock, W. G., 1997. Ethnicity and segregation: post-hurricane relocation. In Peacock, W. G., Morrow, B. H., and Gladwin, H. (eds.), Hurricane Andrew: Ethnicity, Gender and the Sociology of Disasters. New York: Routledge, pp. 191–205.

[13] Dash, N., Peacock, W. G., and Morrow, B. H., 1997. And the poor get poorer: a neglected black community. In Peacock, W. G., Morrow, B. H., and Gladwin, H. (eds.), Hurricane Andrew: Ethnicity, Gender and the Sociology of Disaster. London: Routledge, pp. 206–225.

[14] Yelvington, K. A., 1997. Coping in a temporary way: the tent cities. In Peacock, W. G., Morrow, B. H., and Gladwin, H. (eds.), Hurricane Andrew: Ethnicity, Gender and the Sociology of Disaster. London: Routledge, pp. 92–115.

[15] Bolin, R. C., 1993. Household and Community Recovery After Earthquakes. Boulder, CO: University of Colorado Institute of Behavioral Science.

[16] Sprung, n.d., “Comparison Matrix.” from http://www.sprung.com/sprung-advantage/comparison-matrix

[17] Manfield, P and Ashmore, J and Corsellis, T. 2004. “Design of humanitarian tents for use in cold climate” Building and Research Information, 32(5) pp. 368-378

[18] Select Bipartisan Committee to Investigate the Preparation for and Response to Hurricane Katrina, February 15, 2006, “A Failure of Initiative.” 2nd Session of 109th Congress U.S. House of Representatives


http://www.sprung.com/sprung-advantage/comparison-matrix

http://www.unhcr.org/pages/49c3646cf2.html

[19] Cohen, C. and Werker, E., 2008, “The Political Economy of ‘Natural’ Disasters.” Working paper.

[20] Environmental Building News, 1993, “Cement and Concrete: Environmental Considerations.” Volume 2, No. 2

[21] Fluegel, L. and Rein, B., 1989, “Arc Welding Safety.” University of Arizona Cooperative Extension.

[22] McDowell, M. A., et al. October 22, 2008, “Anthropometric Reference Data for Children and Adults: United States, 2003-2006.” National Health Statistics Reports 10.

[23] Safety Info, n.d. “Concrete Mixing and Placement.” from https://www.safetyinfo.com/guest-library/materials/written-safety-programs/concrete-mixing-pouring-safety-program

[24] Sawisch, M., n.d., “Deadly CO Emissions: How to Prevent Carbon Monoxide Poisoning.” from http://www.electricgeneratorsdirect.com/stories/7-How-to-Prevent-Carbon-Monoxide-Poisoning.html


http://www.electricgeneratorsdirect.com/stories/7-How-to-Prevent-Carbon-Monoxide-Poisoning.html

http://www.electricgeneratorsdirect.com/stories/7-How-to-Prevent-Carbon-Monoxide-Poisoning.html

https://www.safetyinfo.com/guest-library/materials/written-safety-programs/concrete-mixing-pouring-safety-program

https://www.safetyinfo.com/guest-library/materials/written-safety-programs/concrete-mixing-pouring-safety-program

7. APPENDICES

Appendix A: Impact on SocietyAppendix B: Foundation System AnalysisAppendix C: Structural System AnalysisAppendix D: Fabrication Plan


Appendix A: Impact on Society

IntroductionBecause one of the main uses of the Tensioned Building Construction project is for

humanitarian aid purposes, the project will have a large impact on society in many different

ways. Disasters occur throughout the world and in many different circumstances. In almost every

case of a natural disaster, people are forced to leave their homes, whether due to structural

failure, flooding, or continuous dangerous conditions. With a mass exodus of people fleeing their

homes, a means of temporary housing is ideal. Temporary housing is ideal because of the few

long-lasting effects that it has on the environment, while maintaining a safe living space for those

occupying it.

SocialThe Tensioned Building Project will have an enormous social impact through its use in

humanitarian aid. One of the main concerns in prevention of natural disasters is the

disproportionate effect that they have on the members of society with regards to the

socioeconomic status of its members. Because of their lower socioeconomic statuses, people are

more likely to live in hazard-prone locations and physically vulnerable structures [10] [11]. Once

these people are subjected to a natural disaster in which they require aid, the lower-income

people often have fewer resources on which to draw for recovery. Because of this, those families

are unable to return to their homes for much longer than those of a higher income and require

temporary housing for a longer amount of time [12]. This can have a huge impact on a society. If

there is a lack of alternative housing after the destruction of a residential area within that same

area, then people are more likely to move to a new location that has not been as severely

affected. In one case, after Hurricane Andrew, many homeowners left the Miami area with

population losses up to 31%. Many of those unable to leave were forced to remain in severely

damaged or condemned buildings [13] [14]. Through the use of the Tensioned Building Project,

temporary housing can be deployed in many different disaster-stricken areas, preventing the

societal collapse of that area.

Economic


Because the majority of those that require temporary housing are of lower socioeconomic

statuses, as stated in the above section, the economic recovery of stricken areas is significantly

slower. It was seen that the larger the family and the lower the socioeconomic status, the less

likely the household was to receive disaster relief, have adequate insurance or receive adequate

aid despite being more likely to require it. Households with lower incomes, the number of which

is often much greater than the number of households with high incomes, are unable to reenter

society and provide for their families. It was also seen that those who suffer the greatest loss to

material resources are likely to experience the most psychological distress [15]. The Tensioned

Building Construction project could be used to speed up the economic recovery of a disaster-

stricken area due to its inexpensive nature. While some modifications can be made to enhance

either the insulation quality, size, or stability these require an increase in price. The base

specifications of the structure remain under $10 per square foot, while most temporary structures

today range between $25 and $55 per square foot [16]. While these structures are not identical in

nature, they are manufactured for the same purpose of temporary housing.

Ethical

An ethical theory is the theory that the rights set forth by a society are protected and

given the highest priority. One of the rights set by our society is the right to shelter, which was

shown during Hurricane Katrina when the government, through FEMA, attempted to house all

those displaced by the storm. Because FEMA was unable to do so with the materials at hand,

ethically they needed an alternative solution. Because the Tensioned Building is inexpensive and

quick to produce this would have benefited society’s ethical belief that those people had the right

to shelter

While the Tensioned Building is more inexpensive then most temporary structures, it is

more expensive than the average tent. The UNHCR (United Nations High Commissioner for

Refugees) commonly uses canvas tents when aiding internally displaced people [1]. While these

tents are inexpensive with only one unit costing $500 [17], living in one provides very little

dignity to the user. Tents provide no dignity because the user does not feel adequately housed,

nor is the structure properly insulated. A large amount of heat is lost through both the ground and

the canvas fabric. Having a firm structure with adequate housing provides a dignified space


where displaced people can live until more permanent housing can be arranged. Most

considerations of ethics take into consideration the need to do the most good. Providing dignity

to those in need falls under this category.

PoliticalThe impact that disaster relief has on politics can be seen throughout the world. When

there is a natural disaster somewhere, that area is overwhelmed with humanitarian aid and,

depending on the location, this aid can come from within the country or from another country

altogether. Within many different regions of the world, contingencies such as levees are put in

place by the government in cases of natural disasters. One example that shows these

contingencies within the United States is during Hurricane Katrina which saw one of the most

controversial disaster relief responses seen in modern day times when the levees failed to hold

back the higher water levels in New Orleans, Louisiana. Some relief problems that were

encountered with Hurricane Katrina were that the buildings used as temporary shelter after the

storm were not prepared for that type of use, there was no database of available relief and over

200,000 trailers were ordered as temporary homes for the displaced people of the southern region

of the United States but only 6000 units could be manufactured per month [18]. These kinds of

problems are encountered all over the world, but in many cases the outcome could have been

much worse. After Hurricane Katrina over 85,000 hotel rooms nationwide were utilized as

temporary housing; however, this is not always an option in poorer countries and more remote

areas [18]. The Tensioned Building would alleviate some of these problems with its simple and

inexpensive design, while maintaining structural integrity.

Another impact that this design could have on politics is its ability to allow poorer

countries to provide aid to its own people in times of need. Often times these countries rely on

international humanitarian aid and will under-invest in disaster prevention because they know

they will be bailed out of these types of situations by wealthier countries [19]. While the

Tensioned Building will not entirely fix this problem, having an inexpensive system of

temporary housing could allow a country to utilize its finances to better aid their own citizens. In

the long-run this could help provide a more stable infrastructure for the country.

Environmental


The impact that this design will have on the environment is very limited. The main

concern for the environment in this design is the production of the concrete for the foundational

blocks. The main component of concrete is cement which has one of the most energy-intensive

productions of all industrial manufacturing processes. However, all of the other components of

concrete—sand, crushed stone and water—take significantly less energy for production. Within

cement production, kilns are used to heat the cement. Within these kilns, hazardous waste is

burned as fuel including motor oil, spent solvents, printing inks, paint residues, cleaning fluids

and scrap tires. In fact in many cases cement kilns are the only way to safely burn the waste. The

production of concrete does produce CO2 emissions and waste water pollution. However,

looking at all structural material production, the only material that has an overall lower embodied

energy (the energy consumed by all of the processes associated with the production) is wood. All

other structural materials require more energy to manufacture and produce [20]. Also due to the

design of this project, significantly less concrete is used than in a standard housing unit. Looking

at the dimensions as given by the design document, 15’ x 23’, the concrete foundation of a

standard housing unit with these dimensions (assuming a 3’ depth for the foundation), 115.25

cubic feet of concrete would be required as opposed to the 47.75 cubic feet required for the

Tensioned Building. There is such a great difference in these sizes because most homes have a

concrete foundation throughout the entirety of the house, while the Tensioned Building only has

concrete under the structure supports. Overall this design will only impact the environment in the

production of the cement.

Health and Safety

With any form of engineered product, there will be some exposure to hazards and unsafe

situations whether it is in the manufacture of the product or in the consumer’s use of the product.

The main workplace hazard that will be seen in the manufacture of the Tensioned Building is in

the welding of the brackets that hold the structure in place. The following are the main concerns

for welding as determined by OSHA, the Occupational Health and Safety Administration. The

first is inadequate ventilation. According to OSHA the welding area should have a ventilation

system that moves a minimum of 2000 cubic feet per minute of air per welder. [13] Another

concern is fire. Metal sheets or fire resistant curtains should be used as fire barriers, welding


should be done on a concrete floor and there should be suitable fire extinguishing equipment

readily available. The next concern is the personal protection of the welder. Due to the high heat,

sparks and ultraviolet rays produced, the welder should wear a protective face shield with filter

lens, a flame proof shell cap, a buttoned collar, long sleeves, fire-resistant gauntlet gloves and

steel-toed boots. Finally, because arc-welding requires electricity to operate, electric shocks are a

large concern. To prevent these, welding should be done on an insulating mat or other non-

conductive material [21]. In addition to these safety precautions, all brackets were designed to

optimize the simplicity of the welding.

Due to the simple onsite construction, there are few safety concerns for the consumer of

the Tensioned Building. One safety concern is entrapment, or when a body part is pinched

between or trapped beneath some form of equipment. In the construction of the tensioning and

structural subsystems different body parts such as fingers or hair could get caught in the

turnbuckles or in the brackets. To prevent this gloves should be worn during construction and all

loose hair should be tied back. Also through manufacturing, some edges of the brackets could

have sharp edges. While these edges will be smoothed within the manufacturing process, to

prevent injury gloves should be worn and care should be taken when operating the brackets.

Because the structure (11.75 ft.) is taller than the average man’s height (5 ft. 10 in.) a ladder will

be necessary to complete the assembly of the structure [22]. The safety instructions that the

ladder provides should be carefully adhered to. Finally the pouring of the concrete for the

foundational blocks will present some hazards to the user. Engulfment, skin irritant, form

blowout, noise exposure, eye hazards and impact and pinch points are all possible safety

concerns when pouring concrete. By following OSHA standards and using proper moisture

content according to design specifications, following the appropriate procedure and wearing eye

and hand protection the concrete can be safely poured [23].

Once the product is in use, the main safety concern is the ventilation of the structure. The

structure should not remain entirely sealed, with all windows, doors and interior and exterior

fabrics completely closed for extended periods of time. Also with the limited ventilation of the

structure, fuel-based generators should not be used within the structure. If these are used within

the structure the user will potentially be exposed to carbon monoxide poisoning [24].

Manufacturability


Many aspects of this design are simple to manufacture or can be purchased. The

structural and tensioning materials can be simply cut to the correct length. This can be done via

shears for the tensioning material, and can be done via band saw or hack saw for the structural

material. However, the two areas of the structure critical in manufacturing are the brackets and

the foundation.

The brackets will be manufactured out of aluminum tubing while the structural members

will be made out of PVC tubing. There are a couple of reasons for this. First, the area of

maximum stress for all simulations done was located in the joints of the structure where the

brackets will be located so the brackets joint interfaces need to have high yield strengths and this

can be obtained through welding. This leads to the second reason, which is that aluminum is

much easier to manipulate and manufacture than PVC, mainly because you cannot weld PVC.

Pre-fabrication for welding will include using the drill press and a hole saw to cut the correct

curvature out of the piece of tubing that will be welded onto another tube. This curvature is

needed so that the sides of the tube will be flush and allow for easier welds. Once this is

completed so that all of the pieces will mate correctly for welding, the mill will be used to

complete the rest of the pre-fabrication. This can be done using two separate programs with the

mill for all pieces. This will include cutting the hole for accessing the turnbuckle as well as

placing each pin hole. Once this is completed the pieces will be welded. This will complete the

manufacturing for all bracket joints that are right angles. All angles less than ninety degrees will

be manufactured using hinge joints that can be purchased. These joints can be easily integrated

into the already manufactured brackets by simply being bolted to the section closest to the actual

joint interface. Lastly the pins can be easily inserted to function as an anchor for the turnbuckle

as well as stoppers for the PVC.

The foundation will require some manufacturing work as well. The foundation is almost

entirely made up of concrete. There is a first layer of anchor blocks located at the vertical

structural support posts as well as a second layer of anchor blocks located further underground

between the anchor blocks on the first layer. In order to manufacture these blocks, the anchor

blocks locations will have holes dug out for them to be poured and set. The digging process will

be completed using either shovels or a digging tool dependent on the building site ground

composition. Using QUIKRETE®® concrete, creating the concrete to be poured is very


simplistic and consists of following the instructions given when purchasing the material. The

mixing of the QUIKRETE®® may require renting a concrete mixer due to the amount of

concrete needed to be made. When making the anchor blocks, aluminum tubing will be placed

vertically in the blocks when they’re initially poured and set to provide a holder and support for

the vertical PVC structural support members. The aluminum tubing will also be placed

horizontally so that the tensioning wire for the anchor blocks will be able to attach to each block

easily. To simplify this manufacturing process, single right angle aluminum tubing will be placed

in the blocks to function as the support structure holder and anchor block tensioning material

attachment. Clamps will be used to hold the aluminum tubing in place at the correct angles and a

level to insure correct placement of the components. The concrete foundation is a 1.5” thick slab

that will be sit on top of the anchor blocks. Manufacturing this consists of mixing, pouring and

setting the concrete. This is done the same way that the concrete is set for the anchor blocks. To

avoid the mixed, unset concrete spilling over and setting where it’s undesired, trench support

material will be put around the perimeter of the desired concrete location.

Sustainability

Until an indestructible and low-cost structure is designed, there will always be a need for

temporary structures. Natural disasters are a very common occurrence, causing the displacement

of people in every single one. Because temporary shelter will always be necessary, this design is

very sustainability. Also, as referenced in the environmental section above, because production

of this design has a limited environmental impact, it aids in the sustainability of the entire planet.

Conclusion

The greatest impact that this project will have is on society’s ability to respond to a natural

disaster and temporarily house the people displaced by that disaster. Due to its inexpensive

production and assembly costs, this product can be used all throughout the world when needed.

With its low impact on the environment, this product can be used and maintain its sustainability.

Overall this product will have a very positive impact on the world.


Appendix B: Foundation Subsystem Analysis

When deciding the thickness of the concrete floor, the force that it can withstand is the main component studied. To determine the force that a concrete slab on the ground can withstand the following equation is used:

w=257.876 ∙ s ∙√ k ∙hE

Where w is the maximum allowable distributed stationary live load (lbs/ft2), s is the allowable extreme fiber stress in tension excluding shrinkage stress and is assumed to be equal to ½ the normal 28 day concrete flexural strength (lbs/in2), k is the modulus of subgrade reaction (lbs/in3), h is the slab thickness (in) and E is the modulus of Elasticity for the slab (lbs/in2). E is typically 4 x 106 lbs/in2 so in this case it will be assumed that this is the case [8]. According to the specifications sheet of QUIKRETE®® the compressive strength is equal to 4000 psi with a 28 day cure. The flexural strength can be assumed to be 10-20% of the compressive strength [9] which is equal to 800 psi. Knowing that the slab thickness is 1.5 in we can determine the maximum allowable load.

Table B1. Constant Values for Concrete

s (psi) 435.1h (in) 1.5E (psi) 4.00E+06

The following table is an outline of the moduli of subgrade reaction for different types of soil. These were given in a range so the maximum allowable loading will also be given in a range.

Table B2. Moduli of Subgrade Reactions for Different Soil types

Ground Description k range (psi/in)Well-graded gravel 300 450Silty sands 300 400Well-graded sands, gravelly sands 200 400Fine sand (beach sand) 150 350Clayey sands 150 350Fat (high-plasticity ) clays 40 225Lean (low-plasticity) clays, sandy 25 225Silts, sandy silts 25 200


Using these values the following allowable loads for QUIKRETE®® are determined.

Table B3. Range for Maximum Allowable Live Load for Concrete

Ground Description w range (lbs/ft2)Well-graded gravel 1.09E+03 1.34E+03Silty sands 1.09E+03 1.26E+03Well-graded sands, gravelly sands 8.93E+02 1.26E+03Fine sand (beach sand) 7.74E+02 1.18E+03Clayey sands 7.74E+02 1.18E+03Fat (high-plasticity ) clays 3.99E+02 9.47E+02Lean (low-plasticity) clays, sandy 3.16E+02 9.47E+02Silts, sandy silts 3.16E+02 8.93E+02

To determine if this is a better material to use than wood, knowing the compressive strength of wood to be a range between 2900 and 725 psi, maximum allowable load for a wood floor can be determined.

Table B4. Range for Maximum Allowable Live Load for Strongest Point of Wood


Table B5. Range for Maximum Allowable Live Load for Weakest Point of Wood



As seen above even a ½” slab of concrete built on the worst ground is able to maintain larger loading then the strongest point of a slab of wood. This verifies that the concrete should be chosen over the wood.

The stationary live load is analyzed in this scenario because this is the load that will affect the floor the most. The other type of stationary load (the dead load) encompasses the weight of the roof and walls. Because the primary structure consists of stainless steel and PVC, these loads will not have a great effect on the loading of the floor. Also because the structure is directly connected to the foundation blocks which are not directly connected to the floor the structure does not impose a large load on the floor.

To determine the tensioning required for this system it is first necessary to determine the forces that might be introduced to the system throughout its use. One of the main environmental concerns for this structure is extreme winds. Because air blowing around an object is categorized as turbulent flow this complicates the calculations. To simulate wind flowing over the structure ANSYS Fluent was used. When using Fluent the space that is used to solve the calculations is the space that the fluid occupies. In this case, this is the air flowing around the house. This means that the following shape had to be constructed to determine the flow.

The large space on either side and above the structure allows Fluent to do the correct amount of calculations to see how the pressure and velocity propagate. Once this shape was meshed the solution could be setup. In this case it was assumed that the flow was low-speed and incompressible. By setting the gauge pressure as the ambient pressure and assuming that the lower and upper walls had slip, the pressure and velocity profiles could be determined. These calculations were done assuming that the wind velocity was at Mach 0.1 which is equal to 34.03 m/s or 76.12 mph. The following figures show the contours of the static pressure. The first figure is the entire fluid that was tested in Fluent. The second figure is a zoomed-in portion that shows the area immediately around the structure. The static pressure is the pressure that would be


Figure B1. Fluid Mesh

measured if one were moving along with the fluid. For practical purposes, static pressure is synonymous with pressure.

Figure B2. Fit View of Contours of the Static Pressure

Figure B3. Close-up of Contours of Static Pressure Around Structure

These figures show that the pressure is at its greatest point on the left vertical wall. At this wall the pressure is about 45.6 Pa and as the fluid makes contact with the left roof the pressure decreases. This pressure also causes there to be a force in the positive y direction.

The following figures show the total pressure acting on the structure. The total pressure is the sum of the static pressure and the dynamic pressure, where the dynamic pressure is the kinetic energy per unit volume of a fluid particle.


Figure B4. Fit View of Contours of Total Pressure

Figure B5. Close-up View of Contours of Total Pressure

These figures show that the total pressure that acts on the structure does not exceed 59.5 Pa and on the opposite side of the structure a vacuum is formed.

The following figures show the velocity in the x direction as it makes contact with the structure. Looking at these figures, it can be confirmed that the figures above are correct. This is because as the fluid approaches the structure and contacts it, the velocity decreases causing an increase in the pressure.


Figure B6. Fit View of Contours of X Velocity

Figure B7. Close-up View of Contours of X Velocity

By looking at all of the data found in ANSYS Fluent, the pressure that should be applied to the structure frame to simulate large winds can be determined. Knowing this, the tension required within the system can be calculated.


Table B6. 1/2" Polypropylene Properties

Minimum Breaking Strength 16.8 KNSafe Load (S.F.=12) 1.4N

Max Applied Load S.F.63 (267 N load)

Table B7. 1/2" Polypropylene Length and Elongation

T=267 N T= 26 NPVC Length (ft)

Rope Length (ft) Length (m)

Elongation (mm)

Elongation (mm)

2.27 1.52 0.463296 7.412736 0.74127362.35 1.6 0.48768 7.80288 0.780288

5.5625 4.8125 1.46685 23.4696 2.346966.04 5.29 1.612392 25.798272 2.5798272

6.625 5.875 1.7907 28.6512 2.865127.64 6.89 2.100072 33.601152 3.3601152

7.855 7.105 2.165604 34.649664 3.46496649.5625 8.8125 2.68605 42.9768 4.29768

10 9.25 2.8194 45.1104 4.51104

Tables 10 and 11 shows the ½” Polypropylene rope length and desired elongation for the minimum and maximum tension seen in the rope. This shows the amount that the turnbuckle needs to be tensioned to acquire the desired forces for the structure to be stable.

Appendix C: Structural Subsystem Analysis


Calculations were completed to determine under what force the structural members will begin buckling. These calculations were done assuming the structures were built from rigid PVC. These were the base line calculations done to determine the failure load and stress for each member. These loads are plotted in Figure 11 and are used to determine whether or not certain members are going to fail based on the local stresses given from the structural simulations discussed above.

Buckling Calculations

Critical Buckling Load: Pcr=π2 EI(KL)2

Critical Buckling Stress: σ cr=π2 E

( KL /r )2

Where: r=√I / A

For both ends fixed: K=0.5For pinned and fixed ends: K=0.7For both pinned ends: K=1.0

These calculations will assume that one end is fixed to the foundation, and the other end is pinned give a more conservative calculation. While the other end could be considered fixed, it is not entirely secure, however it is more secure than a pin joint. This assumption will put these calculations on the conservative side of error for safety.

Area Moment of Inertia: I=π4

(r24−r1

4 )Area: A=π (r2

2−r12 )

Where: r1=1∈;r2=1.1875∈¿

For Rigid PVCYoung’s modulus: E=2.41GPa=349540 psiShear modulus: G=866.7 MPa Poison’s Ratio: v=0.3825

A=π (1.18752−12 )=1.2885¿2

I=π4

(1.18754−14 )=0.7764¿4

r=√0.7764/1.2885=0.7762∈¿

L=3.75 ft=45∈¿:

Pcr=π 2 (349540 ) 0.7764

(0.7∗45)2 =2699.4 lbs


σ cr=π 2 (349540 )

(0.7∗45/0.7762 )2=2094.9 psi

L=7.5 ft=90∈¿:

Pcr=π 2 (349540 ) 0.7764

(0.7∗90)2 =674.84 lbs

σ cr=π 2 (349540 )

(0.7∗90 /0.7762 )2=523.72 psi

L=8 ft=96∈¿:

Pcr=π 2 (349540 ) 0.7764

(0.7∗96)2 =593.12lbs

σ cr=π 2 (2.41∗109 )

(0.7∗96 /0.7762 )2=460.30 psi

L=8.14 ft=97.68∈¿:

Pcr=π 2 (349540 ) 0.7764

(0.7∗97.68)2 =572.89lbs

σ cr=π 2 (349540 )

(0.7∗97.68 /0.7762 )2=444.61 psi

L=8.39 ft=100.68∈¿:

Pcr=π 2 (349540 ) 0.7764

(0.7∗100.68)2 =539.26 lbs

σ cr=π2 (349540 )

(0.7∗100.68 /0.7762 )2=418.51 psi

L=11.5 ft=138∈¿:

Pcr=π 2 (349540 ) 0.7764

(0.7∗138)2 =287.03lbs

σ cr=π2 (349540 )

(0.7∗138 /0.7762 )2=222.76 psi

Knowing these calculations the critical buckling load and stress can be completed for varying lengths of PVC. This allows the optimum length to be chosen for each structural member in the building. The graph showing the relation of the length of the PVC to the buckling strength (Figure 35) shows that the shorter the length of the PVC the higher the buckling strength. At the same time a shorter length of tubing will create connection problems if multiple sets of PVC


must be joined to complete one structural member. The free body diagram of the loading of each length of PVC can be seen in Figure C1.

Figure C1. PVC Buckling Loads

Figure C2. Buckling Load vs. Tubing Length


Addition of Structural Member:The initial structure was analyzed via SolidWorks, including both stress and deformation

simulations. The initial load applied was based off the typical conservative value for wind load on a surface for most UK buildings, which was 1.2kN/m2 (engineering toolbox). This value corresponds to the wind load for just less than 38 m/s (1.24kN/m2). When converted to English units this would estimate an 85 mph wind gust creating a pressure of 25.1 psf or 0.17 psi. Three tests were done initially, Simulations 1, 2, and 3. These simulations were done with the properties of rigid PVC on SolidWorks with accurate cross sections for 2” PVC (2.000” ID and 2.375” OD) and joints were defined as either fixed or hinged based on the design. Simulation 1 had a wind load applied only to the side, Simulation 2 (Figure 36) had a wind load applied only to the front, and Simulation 3 had a wind load applied to both the front and the side. Upon analysis of Simulation 2 it was noticed that there was significant deformation in the front cross beam when compared to the deformation in the other two simulations. To account for this a structural member was added in the center of this cross beam and extends to the back end of the structure, adding symmetrical support to the back cross beam. The same three simulations were performed again, Simulations 4, 5, and 6. When analyzing Simulation 5, which had the same constraints as Simulation 2, it was noted that the maximum deformation was approximately 33% less and was centralized in the entire roof structure instead of one beam. Therefore there are more structural members absorbing the wind load as opposed to just the center cross beam. The figures below show exaggerated deformations of a scale 10:1 for the structure before and after the member was added.

Figure C3. SolidWorks Simulation 2: Displacement


Figure C4. SolidWorks Simulation 5: Displacement


The deformation result of Simulation 2 is on the left, showing the maximum deformation is just over three inches and is located in the center of the front crossbeam. This deformation is not ideal in that much of the load is being absorbed by only two structural members in one specific spot on the members. In order to compensate for this an additional support member was added through the center of the ceiling of the structure. Simulation 5, for the deformation of the new structure on the right, shows that the maximum deformation for the same load applied is only two inches, but more importantly it is dispersed amongst the roof structure. It can be seen that maximum deformation is now located within the entire top beam, while the additional member sees slightly less deformation, yet still more than the rest of the structure. This design adjustment was crucial in that it results in more structural members absorbing the deformation allowing the entire roof structure (all three cross brace triangles) to support the load and not just the first cross brace. As described above, Simulations 1, 2, and 3 have identical fixtures and loadings when compared to Simulations 4, 5, and 6, respectively. When comparing Simulation 1 with Simulation 4, and Simulation 2 with Simulation 6, it was clear that the structure with the added member reduced the amount of stress and deformation of the structure, and the locations of maximum stress and deformation remained identical. For this reason only, the analysis of the simulations was focused on Simulations 4, 5, and 6 for the new structure.

Figure C5. Side view of Simulation 2: Displacement


Figure C6. Side view of Simulation 5: Displacement

Once again, the exaggerated deformation results of Simulation 2, on the left, and Simulation 5 (Figures C5 and C6) are shown above, but this time from the side view. Here it can be clearly seen that the first cross brace is deformed much more in Simulation 2 than any of them in Simulation 5. It can also be seen that the top beam sees less transverse deformation, but rather more of an axial shift.

Figure C7. Isometric view of Simulation 7: Deformation


Figure C8. Top view of Simulation 7: Deformation

Figure C7 and C8 show an isometric and top view of the deformation of Simulation 7. Simulation 7 has the same constraints as Simulations 1 and 4 except the force on each member was calculated through the ANSYS Simulation above. This gave a total pressure 16.08 kPa on side of the structure which correlated to a wind of 76.12 mph which is just qualifying as hurricane force winds. The maximum deformation takes place in the long beams on the top and side of the roof at a value of 18 inches. Note that this deformation is high due to the extreme conditions. However, it is not enough to cause buckling.

Figure C9. Isometric view of Simulation 7: Stress


Figure C10. Isometric Close up view of Simulation 7: Stress

Both figures C9 and C10 above show the results from Simulation 7. Here it can be noted that the maximum stress does not occur in the members but at the joints. Figure C9 gives an overall view of the stress distribution and it can be seen that none of the members are at the maximum (red) stress level. In Figure C10 it can be more clearly seen that the maximum stress occurs at the middle side joint and the middle top bracket. This indicates that these two brackets will be most critical for a wind load coming directly from the side.


Resized Structural Analysis:

After reassessing the scope of the project after the loss of a member, the size of the structure was scaled down. Because this new structure is very similar to the old structure, just a smaller version, the results will be compared to the analysis done on the previous design. These simulations will be labeled Simulations 8-10 and also have identical configurations as Simulations 1-3 respectively. Simulation 8 in Figures C11-C14 shows the first configuration with the wind pressure only coming from the side.


Figure C12. Close-Up Isometric view of Simulation 8: Stress


Both figures C11 and C12 above show the stress for Simulation 8 at a side wind speed of 30 mph. Here the maximum stress was found to be only 1,300 psi and was located at the bottom of each vertical member that will be fixed by the concrete blocks. This is much different than the 30 mph analysis on the previous structure, which had a maximum stress of 1,400 psi. While the stress under the same conditions was lower it was also located in the bottom brackets instead of the top brackets. This will allow more of the stress to be supported by the lower brackets that are embedded in the concrete foundation blocks.

Figure C13. Isometric view of Simulation 8: Displacement


Figure C14. Close-Up Isometric view of Simulation 8: Displacement

Figures C13 and C14 above show that the displacement for this simulation was only 3.6 inches which is roughly the same as the 3.3 inch displacement found in the simulation on the previous design. Figures C15 through C17 show the results from the simulation on the previous structure; the simulation to which these results are being compared to. The maximum stress if 1,400 psi can be seen in Figures C15 and C16, while the location of this maximum stress can be seen in Figure C16. For the previous structure the maximum stress is locate on the diagonal PVC members between the double walls. The results for the new design show that the new design has the maximum stress in the brackets instead of the PVC. And because the stainless steel brackets are much stronger than the structural PVC, the new design is more ideal than the previous. Figure C17 shows the displacement for the previous design. It can be seen that the dispalcements are nearly identical and located in the same spot.


Figure C15. Isometric view of Previous Simulation: Stress

Figure C16. Close-Up Isometric view of Previous Simulation: Stress


Figure C17. Isometric view of Previous Simulation: Displacement

Figures C18-C21 below show the results for Simulations 9 and 10. The results of these simulations showed the same trend as Simulation 8 in comparison to the results of the simulations on the previous design. The results for Simulation 9 can be seen in Figures C18 and C19, while the results for Simulation 10 can be seen in Figures C20 and C21.








Bracket Analysis:

Pre-Load:

Figure C19. Stress Caused by 60 lb. Pre-Load


Figure C20. Close-Up of Pre-Load Simulation

Both figures C19 and C20 above show the results of the final simulation with respect to the preload of the tension system. This was done by simulating equal and opposite forces on the lower 7/16” pin and the top of the PVC that is resting on the two 5/16” pins. This was done at various loads to determine an upper bound on the preload based on the stress created by the load on the pins. Loads that were tested were 50, 60, 80, and 100 lbs. From these simulations it was found that a 60 lb. preload is an appropriate maximum preload based on the stresses created in the aluminum tubing of the bracket by the pin. This can be seen as the green area around the lower pin in Figure C19 with a stress around 1100 psi. As seen in Figure C20 the maximum stress is going to occur in the 7/16” pin as a result of the concentrated load from the turnbuckle. This will require steel pins instead of aluminum.

Structural Bracket Analysis:


Figure C21. Structural Bracket Analysis

Figure C21 shows the setup for multiple tests done on the brackets. This test was done with the same technique as for the simulations on the PVC, except the cross sections and material were changed to that of the brackets. Analyses were done for the cross section being used in this construction. At 20 mph the maximum stress for the 309 stainless steel tubing being used is at nearly 5,000 psi. While this seems like a lot compared to the PVC cross sections, 309 stainless steel has a yield strength of 45,000 psi which gives a safety factor of 9 on the location of the most stress.

Table C1: PVC properties

PVC Properties:Yield Strength = 55.16 MPaSafety Factor = 2Max Axial Load = 22.93 KNOur Max Applied Load = 267 N

Table C2: PVC Lengths, Buckling, and Deflection


PVC Length (ft)

Critical Load (N) Buckling Stress (Pa)

Max Deflection (m)

Applied Load Deflection (mm)

1.244791667 2134.668367 5135629.944 1.643794972 0.0556265191.411458333 1660.304078 3994394.385 0.371896564 0.0693985153.536458333 264.4762436 636282.4955 1.559506924 0.249986198

4.078125 198.8853035 478482.4357 1.677927374 1.878385214.515625 74.43773336 179083.8606 0.841618783 0.550880516

4.536458333 66.54961158 160106.4517 1.192454365 0.6440743935.578925 106.2729443 255673.679 1.558216182 1.9874771035.703125 101.6946201 244659.0505 1.998812366 0.378610042

9.661458333 27.33621545 65766.04065 1.992668317 1.154205111

Table C1 contains the different desired PVC tube lengths. It also shows the critical load that makes the piece start to buckle, the stress due to buckling and deflection due to buckling. Table C2 shows the strength of the material as well as the applied loads to obtain a safety factor of 2. This shows the required compression on the PVC from the brackets for the structure to be stable and safe, which is a max of 2135 N and a minimum of 27 N.


Appendix D: Fabrication Plan

1.0 INTRODUCTION1.1 Purpose

The purpose of this document is to outline the fabrication plan which incorporates each fabricated part and their assembly. By the end of this document, the reader should have a complete understanding of the fabrication of each part and its general assembly.

1.2 ScopeThis document describes the fabrication plan of the Tensioned Building. Within the fabrication plan the following will be detailed: the facilities, equipment, tools, materials and personnel resources required to build and assemble the product; the special safety considerations during construction and assembly; the procedures and sequences of construction and assembly tasks; the team responsibilities during fabrication; and the financial considerations for fabrication.

2.0 FABRICATION DESCRIPTION2.1 Facilities

For fabricating the different components for the structure, each individual part will be fabricated in the University of Denver machine shop except for the concrete anchor blocks and floor base. Once all parts are fabricated, the concrete will be made and set at the building site, which is the property near the Aurora Reservoir owned by the University of Denver. The components fabricated in the machine shop will then be put together at the building site.

2.2 Equipment, Tools and Materials2.2.1 Anchor blocks and floor base: The anchor blocks and floor base materials

will consist of QUIKRETE®, 2.5” 309 Stainless Steel tubing, and 2’x4’ wood. The tools and equipment will consist of shovels, a level, drill press, end mill, stationary ban saw, gas cement mixer, and a measuring tape.

2.2.2 PVC structure supports: The PVC structural supports will consist of 2” inner diameter PVC tubing material, measuring tape, and a stationary band saw.

2.2.3 Rope: The rope material consists of ½” polypropylene rope and the tools used are rope clams, measuring tape, hammer, and large shears.

2.2.4 Brackets: The bracket material will consist of 2.5” Stainless Steel tubing, 7/16” steel clevis pins, 5/16” steel clevis pins, hitch pin clips, 2.5” structural pipe fittings, 3/8” steel bolts, 3/8” nuts, 3/8” lock washers, and MAG wire. The tools consist of a drill press, measuring tape, 2.5” hole saw, end mill, stationary ban saw, table grinder, and a MIG welder.

2.2.5 The turnbuckle material will consist of only galvanized steel 4½” hook and hook turnbuckles.

2.2.6 Windows: The window material will be made up of a 2’x4’x0.093” clear acrylic sheet and silicon caulking. The tools will consist of a measuring tape, caulking gun, and a ban saw.


2.2.7 Doors: The door material will be door with frame attached, 2’x4’ wood, and screws. The only tool used for the door fabrication will be an electric drill.

2.2.8 Walls: The material for the wall consists of 70 Denier Ripstop Nylon Fabric and silicon caulking. The tools used consist of clamps, measuring tape, and shears.

2.3 Personnel ResourcesThe personnel resources used to fabricate the structure consists of Dr. Matthew Gordon for help integrating the different subsystems together and John Buckley (runs DU machine shop) for help fabricating the different parts of each subsystem.

2.4 Access and Safety2.4.1 Machine Shop Access Requirements

2.4.1.1 General shop access is available for students who have not completed the machine shop certification course. General access permits use of the band saw, drill press, hand-tools, and the end mills and mini-lathes.

2.4.1.2 Certified shop access is only given upon completion of the machine shop certification course. This allows use of the machine tools, mill and lathe, and the welding area.

2.4.1.3 After-hours shop access is provided only to those who have certified shop access and approval from the shop supervisor or another engineering faculty member. There must be a minimum of two people present, and one certified student can oversee up to five people. The after-hours log must be signed during any and all after-hours shop use. ID card access must be programmed into the door, or keys must be checked out, for after-hours shop access.

2.4.2 General Machine Shop Safety Procedures2.4.2.1 Everyone must always wear safety glasses in the shop.2.4.2.2 Never work in the shop alone.2.4.2.3 Never work in the shop if you are tired.2.4.2.4 If you don’t know how to do something, ask.2.4.2.5 No fooling around or horseplay in the shop.2.4.2.6 Clothing: Wear closed toed shoes that give sure footing. No open

toed sandals are permitted. Loose or hanging clothing such as ties, scarves, loose sleeves, shirttails etc. are prohibited. Do not wear gloves during machine operation.

2.4.2.7 Long hair or long beards must be tied back so that it doesn’t get caught in machinery.

2.4.2.8 No personal music devices.2.4.2.9 Do not operate machinery while taking any medication that warns

against operating machinery (due to drowsiness for example).Going beyond the general shop safety procedures, there are safety procedures specific to each piece of equipment being used.

2.4.3 Stationary Band Saw Safety Procedures


2.4.3.1 Keep hands away from the saw blade of the band sawing machine when in operation.

2.4.3.2 Ensure the power supply is disconnected prior to removal or installation of saw blades.

2.4.3.3 Use a miter guide attachment, work-holding jaw device, or a wooden block for pushing metal work pieces into the blade of the band saw wherever possible. Keep fingers well clear of the blade at all times.

2.4.3.4 When removing and installing band saw blades, handle the blades carefully. A large springy blade can be dangerous if the operator does not exercise caution.

2.4.4 Mill Safety Procedures2.4.4.1 Do not make contact with the revolving cutter.2.4.4.2 Place a wooden pad or suitable cover over the table surface to

protect it from possible damage.2.4.4.3 Use the buddy system when moving heavy attachments.2.4.4.4 Do not attempt to tighten arbor nuts using machine power.2.4.4.5 When installing or removing milling cutters, always hold them

with a rag to prevent cutting your hands.2.4.4.6 While setting up work, install the cutter last to avoid being cut.2.4.4.7 Never adjust the workpiece or work mounting devices when the

machine is operating2.4.4.8 Chips should be removed from the workpiece with an appropriate

chip rake and a brush. The chip rake should be fabricated to the size of the T-slots.

2.4.4.9 Shut the machine off before making any adjustments or measurements.

2.4.4.10 When using cutting oil, prevent splashing by using appropriate splash guards. Cutting oil on the floor can cause a slippery condition that could result in operator injury.

2.4.5 Drill Press Safety Procedures2.4.5.1 Do not support the workplaces by hand. Use a holding device to

prevent the workpiece from being torn from the operator's hand.2.4.5.2 Never make any adjustments while the machine is operating.2.4.5.3 Never clean away chips with your hand. Use a brush.2.4.5.4 Keep all loose clothing away from turning tools.2.4.5.5 Make sure that the cutting tools are running straight before starting

the operation.2.4.5.6 Never place tools or equipment on the drilling tables.2.4.5.7 Keep all guards in place while operating.2.4.5.8 Ease up on the feed as the drill breaks through the work to avoid

damaged tools or workplaces.2.4.5.9 Remove all chuck keys and wrenches before operating.

2.4.6 MIG Welder Safety Procedures


2.4.6.1 Proper flame-resistant protective clothing must be worn to protect against combustion and exposure to the strong ultraviolet (UV) light emitted from the weld arc, which is considerably brighter than other types of welding. A sufficiently dark, opaque, and full face mask, leather welding gloves, and protective long sleeve shirts and pants are required at all times by the operator. No skin should be exposed to the strong UV light. PVC welding curtains will protect bystanders from UV exposure, and nobody is allowed behind the curtains without proper protective clothing.

2.4.6.2 Welding gloves shall be flame resistant and resistant to electric shock. The welding work surface shall also be grounded.

2.4.6.3 Proper ventilation must be used to avoid long term exposure to ozone and other dangerous gases formed by the welding arc. Prolonged exposure can lead to lung damage.

2.4.6.4 The welding area shall be clear of any flammable items, and sufficient fire extinguishing equipment shall be readily available in the work area. All parts being welded must be thoroughly cleaned after machining to avoid the formation of poisonous fumes from heating cleaning and degreasing materials.

2.4.6.5 Complete welding safety procedures can be found in the American Welding Society’s ANSI approved Z49.1:2012 document, Safety in Welding, Cutting, and Allied Processes.

2.5 Financial Summary 2.5.1 A Financial Summary can be seen in the figure below. In can be seen that

separate sections were set for tensioning material, structural support, insulation, enclosure material, windows and door, foundation, and turnbuckles. The top row shows what each column represents for each item in the budget. This includes each number, material, function, unit, price, quantity, cost, and a last column for specifications and comments. This budget was constructed in a way to list relevant alternatives next to each other with a working total at the bottom. This allowed for items to be quickly included and excluded from the budget for a quick financial analysis of different options throughout the project. At the bottom there is a total as well as a cost for all of the free material obtained thus far. This number was added to the original $2,000.00 before the total cost was subtracted in order to see how much money is left from the budget specific to this project. The total cost is kept for a total cost analysis at the end of the project for reproduction without obtaining any free materials.



3.0 FABRICATION PROCESS3.1 Procedures and Sequence of Tasks

3.1.1 The first step in the construction process consisted of fabricating all parts not needed to be constructed at the building site.3.1.1.1 Bracket Fabrication

Figure D1: Bracket number locations

3.1.1.1.1 Turnbuckle access holes clevis pin hole, welding, hole saw, structural pipefitting, and tube cutting general fabrication instructions:

3.1.1.1.1.1 Every bracket will be made up of 2.5” steel tubing, 5/16” steel clevis pins, 7/16” steel clevis pins, as well as hitch pin clips for each clevis pin and will be fabricated in the University of Denver machine shop.

3.1.1.1.1.2 Each turnbuckle access cut will be done on the mill in the DU machine shop. A rectangle program will be set to cut a 1.8” width and 4” length rectangle on each side of the piece being cut with the turnbuckle access. This program will be saved in the mill and can be repeated easily. To mill out the holes a 3/8” end-mill bit will be used, this will be set to an RPM of 400 with a feed rate of 2.25 inches per minute. To mill these turnbuckle access holes the piece will be clamped in a table vice on the mill table with two 2.4” diameter circular piece of wood will be


used as dowels and placed on the outside of each rectangle. The mill drill bit will be placed on the top center edge on the rectangle cut location and the mill program will then be run cutting inward in direction on the piece.

3.1.1.1.1.3 For each hole drilled with the drill press, a center drill bit will be initially used to start the cut in order to ensure the cut is accurately made in the correct location. This center drill will then be removed and then replaced with the right sized drill bit.

3.1.1.1.1.4 For the 7/16” pinholes, a 7/16” drill bit will be used in the drill press after the center drill bit in order to fit 1 7/16” clevis pin in the steel tube.

3.1.1.1.1.5 For the 5/16” pinholes, a ½” drill bit will be used in the drill press after the center drill bit. The piece will then be rotated 90 degrees and a center drill bit and ½” drill bit will be used again in order to fit two 5/16” clevis pins parallel with each other in each side of the steel tube.

3.1.1.1.1.6 Each steel tube (piece) will be cut to the given length using the stationary ban saw.

3.1.1.1.1.7 For each hole-saw cut made, the center drill bit in the hole-saw will be placed 0.5” from the end of the piece and then cut using the drill press. Dowels will once again be placed inside the tube being drilled in order to prevent the tube from being deformed by the table vice used to keep the piece rigid.

3.1.1.1.1.8 For all welds made, the hole-saw cut sides will be placed snug on the second piece and welded together with a MIG welder. To weld the pieces, a weld tack will be made on each side of the welding surface. The rest of the desired welding surface will be then completely welded together. To set up each weld, both a triangle and a level will be used to ensure that all angles were at 90⁰ before the tacks were made.

3.1.1.1.1.9 For each hinged structural pipefitting connected to the brackets, two 7/16” holes will be drilled using the drill press in the center of the tubes 3.5” apart. These holes will then be drilled through the top surface of the tube and not through the entire tube.


3.1.1.1.2 For Joints 1, 2a, 2b, 3, 4, and 7, the brackets will be made up of variations of 28.5”, 14.25” and 10.5” steel tube lengths. The following is the fabrication process for each tube length. The different lengths of each tube used can be seen in the Table D1 below.

3.1.1.1.2.1 For the 28.5” steel tubes, the 5/16” clevis pinholes will be drilled 3.5” from the end of the tube on both sides. 7.5” inward on the tube surface from each 5/16” clevis pinholes, 7/16” clevis pinholes are drilled. 2.5” inward from each of the 5/16” clevis pinholes, the turnbuckle access holes will be milled. Four of these pieces will be fabricated.

3.1.1.1.2.2 For the 14.25” steel tubes, the 5/16” clevis pinholes will be drilled 3.5” from the end on one side of the tube. 7.5” inward on the tube from the 5/16” clevis pinholes, a 7/16” pinhole will be drilled. 0.5” inward from the 5/16” clevis pinholes the turnbuckle access holes will be milled. On the opposite end of the tube from the 5/16” clevis pinholes, a hole-saw cut will be made. Five of these pieces will be fabricated.

3.1.1.1.2.3 For the 10.5” steel tubes, one end of the tube will be drilled with a hole-saw. On the opposite side of the hole-saw cut, 5/16” clevis pinholes will be drilled 3.5” inward from the end of the tube. 1” inward on the tube surface, a 7/16” clevis pinhole will be drilled. Fifteen of these pieces will be fabricated

3.1.1.1.3 For the T-joint bracket (Joint 1), one 10.5” piece will be placed directly in the center of the 28.5” piece and the two will then be welded together with the hole-saw cut of the 10.5” piece flush with the 28.5” piece. On each side of the welded T-joint bracket, a structural pipefitting will be connected with the top bolt hole in the center of the 28.5” tube and the second bolt hole on the 10.5” tube 3.5” down from the initial pipefitting hole.


Figure D2: Joint 1

3.1.1.1.4 For the second T-joint bracket (Joint 2a), one 14.5” piece and one 28.5” piece will be welded together with the hole-saw cut of the 14.5” piece flush with the 28.5” piece. On one side of the welded T-joint bracket, a structural pipefitting will be connected with the top hole in the center of the 28.5” tube and the second hole on the 14.5” tube 3.5” down from the initial pipefitting hole.

Figure D3: Joint 2a

3.1.1.1.5 For the third T-joint bracket (Joint 2b), the bracket will be fabricated exactly like Joint 1, except the structural pipefitting will only be done on one side of the bracket instead of both sides.


Figure D4: Joint 2b

3.1.1.1.6 For the corner brackets (Joint 3), three of the 10.5” pieces will be used. Two steel pieces will also be cut to 20.5” and 19.75” in length. For the 20.5” piece, the 5/16” clevis pinholes will be drilled 6.75” inward from one end of the tube. 2.5” inward from the 5/16” clevis pinholes, the 7/16” clevis pinhole will be drilled. The 19.75” tube will be fabricated the same way as the 20.5” piece, except on the other end of the tube; a hole-saw cut will be made and then rotated 90 degrees and will then be cut again in the mill. This will be done using the same procedure as for cutting the turnbuckle access holes except a half circle will be cut out of the end of the tube. This was effectively the same as using the hole-saw again but only cutting through half of the tube. This will be necessary to prepare the part to be welded at a joint with three members coming together. The 20.5” and 19.75” pieces will be connected on each end opposite of the pinholes. One of the 10.5” pieces will be placed on top of the 20.5” piece with the hole-saw side in contact with the other pieces creating a 90 degree angle with the 19.75” piece. The three pieces will then be welded together. The other two 10.5” pieces will then be placed on each end of the 20.5” and 19.75” pieces parallel with the previously welded 10.5” piece. The two 10.5” pieces will be welded to the bracket. A structural pipefitting will then be connected to the opposite side of the welded connection of the three pieces in contact facing inward. Four of these brackets will be fabricated. For each one, the structural


pipefitting will be placed inward facing the corner bracket opposite of the other bracket width-wise of the structure. This will be necessary to fit all diagonal pieces for the roof.

Figure D5: Joint 3

3.1.1.1.7 For the 4-right angle brackets (Joint 4), one 28.5” piece, one 14.5” piece, and one 10.5” piece will be used. For the 10.5” piece, a mill cut will be made 90 degrees width-wise from the initial hole-saw cut. This mill cut once again will make a half circle cut in the end of the tube, effectively making another hole-saw cut half way through the rotated tube, rather than the entire tube. The 14.5” and 10.5” pieces will then be placed on the center of the 28.5” piece flush with the hole-saw cut sides in contact with each other on each piece to make a 90 degree angle with the 14.5” and 10.5” pieces. The three pieces will then be welded together.


Figure D6: Joint 4

3.1.1.1.8 For the right angle L-shape bracket (joint 5), one steel tube piece will be cut to 10.5” in length and a second piece will be cut to 11.25”. For the 10.5” tube piece, the 5/16” clevis pinholes will be drilled 3” from one end of the piece and a 7/16” clevis pinhole will be drilled 1” inward on the tube surface from the 5/16” clevis pinholes. The other end of the tube will then be cut with the hole-saw. For the 11.25” tube piece, the 5/16” clevis pinholes will be drilled 3” from one end of the tube, and the 7/16” clevis pinholes will be drilled 1” inward on the tube surface. The hole saw cut side of the 10.5” piece and the side of the 11.25” piece opposite of the pin holes will be placed together to make an L-shape and will be welded together. On each side of the welded L-joint bracket, two structural pipefittings will be connected on each side of the bracket with the top bolt hole cut 0.5” from the end of the 11.25” tube on the welded side of the tube and the second bolt hole made 3.5” downward on the tube surface. Two of these brackets will be fabricated.

Figure D7: Joint 5

3.1.1.1.9 For the singular tube brackets (Joint 6), a steel tube will be cut to 16” in length. 3.5” inward from one end of the tube the 5/16” clevis pinholes will be drilled. 7.5” inward from the 5/16” clevis pinholes on the top surface of the tube, a 7/16” clevis pinhole will be drilled. 0.5” inward from the 5/16” clevis pinholes, the turnbuckle access holes will then be milled. On the opposite side of the tube from the 5/16” clevis pinholes,


a 1” hole will be drilled 1” inward from the end of the tube. Twelve of these brackets will be fabricated.

Figure D8: Joint 6

3.1.1.1.10 For the center bracket (Joint 7), 3 of the 14.5” pieces will be used. For two of the 14.5” pieces another mill cut will be made 90 degrees width-wise from the initial hole-saw cut. This mill cut once again will make a half circle cut in the end of the tube, effectively making another hole-saw cut half way through the rotated tube, rather than the entire tube. A 3” steel tube will then be cut to length. In the center of the 3” tube, the two 14.5” pieces with the mill cuts will be placed on opposite ends. The third 14.5” piece will then be placed on top of the 3” tube between the other 14.5” pieces creating 8-right angles. All four pieces will then be welded together to make only one of these brackets.

Figure D9: Joint 7


Table D1: Steel Tube Lengths

3.1.1.1.11 Once all brackets are completed, the clevis pins and hitch pin clips will be inserted into the brackets where the corresponding 7/16” and 5/16” holes will be drilled. The structural pipefittings will then be bolted to the brackets with 3/8” bolts, lock washers, and nuts.

Table D2: Bracket Material

3.1.1.2 PVC Support Structure Fabrication3.1.1.2.1 The 2” PVC tubes are sold in 10-foot lengths. The

following lengths in Figure D3 will be cut using the stationary ban saw and a measuring tape in the DU machine shop.

PVC Piece #PVC Length (in.)

Number of Pieces

1 14.9375 22 16.9375 13 42.4375 44 48.9375 45 54.1875 26 54.4375 27 66.9471 68 68.4375 129 115.9375 1

Table D3: PVC Length


1.1.1.1 Window Fabrication1.1.1.1.1 Two windows will be made of a 2’x4’ clear acrylic

sheet. Each window will be cut to 2’x2’ using the ban saw in the machine shop. This will be done by cutting the 2’x4’ acrylic sheet in half.

1.1.1.2 Rope Fabrication1.1.1.2.1 The ½” polypropylene rope will be cut using large

shears to the following lengths corresponding to each PVC piece as shown in Table D4 below.

Table D4: Rope Length for corresponding PVC

1.1.1.2.2 Each piece of rope will be crimped by taking the end of the rope and creating a ½”-3/4” loop. The two sides will then be placed in the rope clamp and the tabs of the clamp will then be hammered down until the rope is secured in the clamp. Each rope clamped will make each rope length 5” shorter and this will be accounted for in the measurements.

1.1.1.2.3 A completely opened turnbuckle will then be attached to one end of each rope.

1.1.1.3 Anchor Blocks Fabrication1.1.1.3.1 The anchor blocks will be fabricated on site, which will

require turf preparation as well as mixing and pouring concrete. A spade shovel will be used to dig out the holes for each concrete block. The blocks will have 2.25 cubic feet associated with each vertical support. This will result in the combining of blocks between shared double walled supports having an “L” shaped primary foundation block that will consist of combining three 1.5’x1.5’x1’ blocks. All of the anchor blocks will be tensioned together by an underground polypropylene rope. This rope will be put in place when the concrete is


poured and will run along the perimeter of the structure. This will require digging out a small trench for it to be buried in so it can run parallel to ground level from block to block. Once the concrete is set for the anchor blocks the exposed rope will be buried beneath the ground level.

1.1.1.4 Wall Fabrication1.1.1.4.1 The 210 Denier Double-wall Ripstop Nylon Fabric

comes in 15”x32’ rolls and will be used for the exterior walls. For the long wall sides, 8 pieces will be put together with 3” of overlap using silicon caulking to connect the nylon pieces. Note that when using silicon caulking to connect pieces, it should be applied in small dabs 6” apart instead of a straight line. This will make an 8’x35’ piece. This will be done three times to create 3 8’x35’ pieces. The three pieces will then be connected with silicon caulking with a 9’ overlap creating a 77’x8’ piece to put around the entire outer wall. At the very bottom and top (8’ up) of the fabric sheet, 25 4” nylon pieces will be connected 3’ apart to create a belt for the ratchet strap to go through in order to secure the wall to the structure.

1.1.1.4.2 For the roof, 19 rolls of the 210 nylon will be put together with silicon caulking with a 3” overlap of each connection to create a 19’x35’ piece which will be placed over the roof of the structure. 25 4” fabric pieces will be placed 2.8’ from the edge of the fabric sheet for a ratchet strap to be put through acting as a belt to secure the roof to the structure. There will be 1’ of fabric extra on each side, which will be connected to the nylon sheet for the wall.

1.1.1.4.3 For the interior wall, 70 denier Ripstop nylon fabric will be used. This material comes in the same size rolls as the 210 nylon. The interior wall will be done the same way as the exterior wall above, except the 77’x8’ final piece will be cut to 70’x8’. There will be a “belt” created for the ratchet straps for the interior wall at the top and bottom, but there will only be 23 belt pieces of nylon due to the decrease in area that the interior wall encloses.

1.1.1.4.4 Using a razorblade, there will be holes cut in the fabric where the door and windows will be installed.


1.1.2 Construction at the Building Site1.1.2.1 Foundation Block Fabrication

1.1.2.1.1 For the foundation blocks, the perimeter of the structure will be zoned on the building site and holes will be dug at each block location. Each block hole will be approximately 6.75 cubic feet. The holes will be 1 foot deep and a symmetric “L”-shape. The eyehooks will then be placed 6” deep and inserted into the ground from the anchor block hole on each of the two 1’ sides. There will be four of these submerged blocks. Each block will be placed on the corner of a 13’x11’ rectangle for the outer sides of the blocks with the “L” shape making up the corners as shown in Figure D10.

Figure D10: Floor Base

1.1.2.1.2 The QUIKRETE® will then be mixed in a gas cement mixer and poured in each of the anchor block holes. After the QUIKRETE® has set for 30 minutes, three joint 6’s will be placed 3” into the QUIKRETE® with the clevis pins on the top of the joints when placed. The joints will be placed in the middle of each 1 cubic foot square and measured with a level to insure they are straight. See QUIKRETE® spec sheet for more specifics of pouring the concrete.

1.1.2.1.3 Then the pre-cut PVC pieces will be placed into the brackets and each corresponding corner (#3) bracket will be placed on top of these pieces of PVC. This will


ensure that each of the #6 brackets will be correctly spaced and perpendicular to the ground.

1.1.2.1.4 Once the concrete begins to set and the #6 brackets can no longer be easily moved, the corner (#3) brackets and PVC pieces will be removed.

1.1.2.1.5 Each anchor block will then be covered with a tarp to protect against rain and other environmental factors.

Figure D11: Anchor Block

1.1.2.2 Concrete Floor Fabrication1.1.2.2.1 Once the anchor blocks are set and hardened, the entire

surface between the 4-anchor blocks locations will then be dug 2” deep and flattened. The floor will be dug up with a spade shovel and then flattened with a tamper. A large level will also be used to ensure that the floor was not slanted.

1.1.2.2.2 QUIKRETE® for the floor will then be mixed in the cement gas mixer and poured. This will need to be done quickly in order to ensure that all of the floor can set as one concrete slab.

1.1.2.2.3 At the location in the wall where the door will be mounted, a 2x4 of wood will be embedded into the concrete so that the door frame may be mounted. The concrete will be poured from one end of the structure to the other, so that it can be initially smoothed and


leveled. The floor was then smoothed out as needed to provide a flat finish. See QUIKRETE® spec sheet for more specifics of pouring the concrete.

Figure D12: Floor Base


Figure D13: Anchor Blocks Relative to Ground

1.1.2.3 Structure Assembly 1.1.2.3.1 For each vertical #6 bracket connected to the anchor

blocks, PVC pieces #8 will be placed in the joints with the turnbuckle and corresponding rope for the PVC piece within the PVC piece and the turnbuckle will be attached to the 7/16” clevis pin in Joint #6.

1.1.2.3.2 Each of the #3 brackets will be attached to the top of the 3 PVC pieces placed in the joint #6’s with the other end of each piece of rope attached to the corresponding 7/16” clevis pins in the #3 brackets.

1.1.2.3.3 The following schematics will be used to connect all PVC, bracket and rope pieces to each other. Each PVC connection has one end with a turnbuckle access hole, and one without any holes. Each end that connected to a bracket piece with a turnbuckle access hole is the side that has the turnbuckle.

Table D4: Rope Length for corresponding PVC


Figure D14: Tensioned System Assembly Figure D15: Bracket (Joint Number) Locations

Figure D16: PVC Number Locations 1 Figure D17: PVC Number Locations 2

1.1.2.4 The turnbuckles will be tensioned to provide support to the entire structure.

1.1.2.5 The door will be placed on the short side of the structure with one side of the frame placed against the side vertical PVC piece. The bottom part of the doorframe will then be screwed into the 2”x4” piece of wood imbedded in the concrete floor base.

1.1.2.6 The interior wall will be wrapped around the interior PVC members and adhesively stuck to the PVC members and cement where contact is made. This will be done again for the exterior wall and roof fabric.


1.1.2.7 Where there will be two holes cut out of the fabric walls, the clear acrylic sheet windows will be placed and adhesively connected to the fabric around the perimeter of the wall using silicon caulking with a 1” overlap with the acrylic and fabric around the entire perimeter of the acrylic.

1.1.3 Fabrications Tips and Tricks1.1.3.1 Structural Pipefitting Attachment

1.1.3.1.1 For bolting the structural pipefittings to the brackets, some of the nut connections within the brackets will be hard to reach by hand to secure the nut while tightening the bolt. The trick to this is to tape a wrench to the end of a square metal bar. The bottom side of the wrench where the nut is placed will be taped off with packaging tape to insure the nut will stay in the wrench. The washer and nut will then be placed in the wrench and placed within the bracket under the pipefitting hole. The bolt is then placed in the hole and tightened from the bolt side with another wrench.

1.1.3.2 Turnbuckle, Rope, and PVC Attachment1.1.3.2.1 When constructing the structure and tension subsystems

at the construction site, there are a few tricks to successfully connecting the PVC, rope and turnbuckles to the brackets. When attaching the corner brackets and brackets placed in the anchor blocks, the first step is to attach all three of the non-turnbuckle sides of the rope to the 7/16” clevis pins in the corner bracket. The 7/16” clevis pins will be removed from the corner bracket, the rope will be placed in the bracket so that the clevis pin can then be placed back into the bracket and be attached to the rope. The three PVC pieces will then be installed into the brackets in the concrete. The corner bracket will be held above the tops of the PVC and the turnbuckles attached to the other side of the rope will then be placed through the PVC members and the bracket connected to the tops of the PVC. The turnbuckles will then be able to be easily attached to the corresponding 7/16” clevis pins and tensioned.

1.1.3.2.2 For the horizontal PVC & rope members, the non-turnbuckle sides of the rope will be connected to the corresponding 7/16” clevis pins the same way as the corner bracket ropes and pins are described how to be connected above in 3.1.3.2.1. The turnbuckle is then attached to the other side of the rope, put through the


PVC member, and then the PVC will be placed in that bracket. The turnbuckle and rope will then be placed into the other bracket and the PVC will then be placed in the bracket as well.

1.1.3.3 Enclosure Attachment1.1.3.3.1 When attaching the enclosure system it was found that

the larger the area between structural members the more the walls would flap in the wind. To reduce this effect more of the belt applications (discussed in enclosure section of the fabrication plan) could be applied to hold the wall more securely, or smaller structural members could be added to reduce these open areas.

1.1.3.3.2 When attaching the enclosure system to the structure system it was also found that the wind created and issue with the drying of the caulking. To mitigate this issue, while still only using the caulking method, the enclosure system should be attached to the structure with little to no wind. Another way to mitigate this issue would be to use more of the belt applications to put the enclosure on initially, and then reinforce these belts with caulking.

1.1.3.3.3 It was also found that the silicon caulking took longer to dry against hard plastic to fabric interfaces (PVC and acrylic sheet) than for fabric to fabric interfaces and should set over night to ensure that the caulking is completely dry. If this is not done it is possible for the caulking to fail due to wind before it is completely set.

1.1.3.3.4 Lastly it was found that when attaching the enclosure system it is crucial to have all sections completed previous to attachment. This will ensure that all sides as well as the roof will be enclosed at the same time reducing the effect of any winds on the inside of the structure. This will allow for the caulking to set more securely because there will be less stress on the interface that the caulking is binding together.


3.2 Responsibilities of Team MembersLuke: Bracket fabrication, PVC fabrication, rope fabricationRobert: Bracket fabrication, PVC fabrication, rope fabricationDani: Wall fabrication, door fabrication, window fabricationAll: Anchor block fabrication, construction of structure at building site once all parts were fabricated.
