Fettuccine bridge Full report

SCHOOL OF ARCHITECTURE, BUILDING & DESIGN Research Unit for Modern ArchitectureStudies in Southeast Asia Bachelor of Science (Honours) (Architecture)

Building Structures (ARC 2523) Prerequisite: Building Construction 2 (ARC2213) ____________________________________________________________________

Project 1

Fettuccine Truss Bridge

Loo Giap Sheng 0310390 Gan Chin Bong 0313738 Teo Kean Hui 0310165

Ng You Sheng 0309997 Kong Chee Seng 0308360

Table of Content

1.0 Introduction

1.1 Aims & Objectives

1.2 Project Scope2.0 Precedent Study

2.1 Overview2.2 History2.3Structure Details

3.0 Materials Study

3.1 Fettuccine 3.2Materials & Equipment

4.0 Design & Structure Analysis

4.1 Design 1

4.2 Design 24.3 Design 3 & 44.4Design 5 & Final Design

5.0 Conclusion6.0 Appendix

7.0 References

1.0 Introduction

1.1 Aim & Objectives

The objectives of this project are as follows:

To develop student’s understanding of tension and compressive strength ofconstruction materials

To develop student’s understanding of force distribution in a truss To design a perfect truss bridge which fulfils the following criteria:

High level of aesthetic value Minimal construction material

1.2 Project Scope

As a group, we are required to carry out precedent study of a truss bridge. Then, we have todesign and construct a truss bridge using fettuccine and adhesive materials such as glue. Thebridge must be at least 750 millimetres of clear span and weight not more than 200 grams.The structure is then tested to carry load until it breaks.

Efficiency of the bridge can be calculated as follow:

Efficiency, E = (Maximum Load)² / Weight of Bridge

In order to achieve higher efficiency, structure analysis have to be carried out to study anddetermine members of tension and compression. Several times of load testing have to becarried out to identify structure failure point and weaker truss members.

2.0 Precedent Study

To have better understanding of truss bridges, appropriate precedent study should becarried out. The following is our study of truss bridge:

Image 2.1: Perspective view of the bridge. Source: Sun Current

Name: Long Meadow Lake Bridge

Location: Old Cedar Avenue at Minnesota River, Bloomington, Hennepin.

Largest spam: 170.0 feet

Total length: 864.5 feet

Deck width: 21.0 feet (2 lanes)

Materials: Steel and Iron

Type of truss: Camelback truss

Diagram 2.1 above shows camelback truss. Source: Wikipedia

2.1 History

The Long Meadow Lake Bridge is a five-span through truss camelback bridge that was builtin 1920. Before the highway 77 overpass opened in 1981, it was one of the few bridges thatconnects traffic from Old Cedar Avenue to Dokata County. This bridge was given to the Cityof Bloomington by the State of Minnesota in 1981, and was still open to automobile trafficas late as 1993. It remained open to pedestrian and bicycle traffic after it was closed tovehicle traffic. In the early 2000s, the bridge deck was declared to be unsafe. The bridge wasdeemed unsafe again in 2002, and had to be barricaded at each end. It was scheduled to berehabilitated beginning in 2014. The builder of this bridge was Illinois Steel Bridge Co. OfJacksonville. The bridge today called Old Cedar Avenue Bridge and had average daily trafficof 400 vehicles.

Image 2.2 showing the bridge was closed down in 2002. Source: Johnweeks

Image 2.3 showing the spring flood in 2010. The water level is just under the bridge deck.

Source: Johnweeks

2.2 Structural Details

Image 2.4 showing the beams and decking of the bridge. Part of the decking had alreadyteared off. Source: Johnweeks

Image 2.5 shows the connection between girders and a stringer at the abutment. Note thatyou can see daylight through holes at several spots on this beam, and that the stringer isrotted through on the right side of the image. Source: Johnweeks

Image 2.6 showing the bridge bearing at the end of the structure. The bridge structure ispushed fully back up against the concrete abutment. This is most likely caused by the bridgesagging due to a weakened structure. The pressure is causing the concrete to crack. Source:Johnweeks

Diagram 2.2 showing the joints at the corner end of the bridge. Source: Past-inc.org

3.0 Material Study

3.1 Fettuccine

Fettuccine is used as the main material for the bridge construction. Before use, fettuccineneed to be check and filter out those that are twisted; it is to ensure that the load is able todistribute evenly and effectively through the flat surface of the fettuccine.

Dimension: 250mm x 5mm (average)

Tensile strength: ~2000psi

Stiffness (E=stress/strain): ~10,000,000psi

We have tried 2 types of fettuccine to test its strength and weakness:

San Remo Spinach fettuccine

San Remo fettuccine

Strength of material is analyzed:

Greenish yellow Slightly harder than normal fettuccine Surface a bit round

Gold Yellow Softer than the spinach fettuccine Flat surface Ratio of usable fettuccine is higher

Shear force Shear force

When the fettuccine is laid flat and the force is only applied on the middle, bending willoccurs due to tension and compression.

When the fettuccine is put upright, the thickness of the fettuccine provide more tensilestrength then laying it flat. However the narrow surface’s load distribution is much lesserthan flat surface, this increases pressure on the structure.

Solution:

Image 3.1 shows force acting on ‘I’ beam structure.

‘I’ beam structure is use; both advantages of horizontal and vertical position are able to beput in use. When the vertical member is placed in between two horizontal members, thehorizontal members will enhance the load distributions and the load will transfer to thevertical member which can withstand more loads.

Image 3.2 shows force acting on one side of solid structure

By adding more vertical members, it enhances the load transfer from horizontal member tothe vertical members.

Shear force Shear force

3.2 Materials & Equipment:

PVA UHU Super Glue (Selleys)

Water based gluecauses fettuccine tosoften

Take long time to dry

Weak joints

Take long time to dry

Joint not rigid

Shifting occurs whenload apply on it

Dry within 10-20 seconds

Produce strong and rigid joints

Surface that was applied once can’t be apply on again

There are other equipment to aid this project:

Luggage scale (max. 5kg)- Act as a hook between bridge model and water pail, at the same time determinethe weight of the load.

Water pail -Act as a container to carry loads.

Camera-Record down the procedure of load testing, to determine which part of the structurecauses failure.

Mineral bottles (500ml)-Use as the standard addition of weight during load testing.

4.0 Design & Structure AnalysisWe did six bridges in total, in five different designs, to test out whether different designs willhave different outcome.

4.1 Design 1

Image 4.1.1 shows the first design of our truss bridge

For the 1st design, we decided to start off with a Truss bridge with curved top chord. So, wesearched of type of truss which is bowstring arch truss where the top chord is a true arc andhas diagonal load-bearing members. Then, we decided to add in hinged arch which islocated at the bottom sides of the truss bridge that is supposed to transfer load to the edgeof tables. At the middle of the bridge where force is being act on is like a 'H' letter where 1beam is laid perpendicularly on top of 2 other beam to transfer load more equally ratherthan just acting in the middle. The distances between the trusses are the same throughoutthe bridge design.

Structure Analysis

Diagram 4.1.1 shows the force analysis of our first design

Bridge Details:

Weight of the bridge: 246 g

Clear Span: 750mm

Width of the base: 120mm

Height: 130mm

Maximum Load Capacity 3.3 kg

Efficiency: 44.3

The load is from the middle part of the bridge, we place the truss in this arrangement so thatthe load can be transferred to other parts of the bridge. The top part we design it to becurved because curve is a pre-bend structure, and when it receive load from the bottom, itwill be pulled down and trying to get back to its original form, so it will be more flexiblewhen compared to straight structure.

Model Test

Image 4.1.2 shows the fettuccine bridge has been set up for testing and use water as load.

Image 4.1.3 shows the water has been pour into the bucket, the fettuccine bridge startedbending downwards slowly as the load is getting more.

Image 4.1.4 shows the bridge’s members started to fall apart when it reached 2.5 kg.

Image 4.1.5 shows the bridge broke at 3.3kg.

Cause of failure

Image 4.1.6 shows the weak and breaking members of our bridge

As this the first fettuccine bridge that we have ever built, we still unable to understand theproperties of fettuccine and how it work. Besides lack of understanding, we also lack ofworkmanship that cause the bridge came up with unbalance structure from both sides andsome members are not attached to the structure properly.

4.2 Design 2

Image 4.2.1 shows the second design of our truss bridge

From the 1st process, we understand that the hinged arch at the bottom does not provide asmuch load-transfer but only stabilize the bridge. Therefore, for the 2nd design approach wereduced the size of it. Not only that, we tried to curve the horizontal member of the bridgehoping it achieves the potential to pre-bend to sustain more load before it breaks. Also, wechanged the design of the truss where instead of a truss design, we connect vertical load-bearing member tangent to the top chord. The reason we did this is because we were tryingto predict the direction of the force so that it is parallel to the vertical members. By doing so,the whole bridge actually serve more as a cable bridge than a truss bridge where most of theforces are tension beside top chord and the horizontal members. The distances betweentrusses are also modified where it slowly expands exponentially from the middle to bothsides. This is to support the heavy force acting to the middle of the bridge and reducing themembers at the sides because they usually receive the least force.

Structure Analysis

Diagram 4.2.1 shows the force analysis of our second design

Bridge Details:


Clear Span: 850mm


Height: 130mm


Efficiency: 81.8

For this design, we place the truss in this way is to predict the direction of magnitude oftensile force in different position of the total bridge span. Using the same theory from theprevious bridge, now we made both top and bottom part of the bridge structure to becurved. After testing, the problem is the curve is not strong enough and fails to transfer theload to two sides of the structure.

Model Analysis

Image 4.2.2 shows the fettuccine bridge has been set up for testing and water as load.

Image 4.2.3 shows the bridge is tested with 2 kg initial weight.

Image 4.2.4 shows when the load is getting more, the pre-bend fettuccine bridge started tobend downwards. The base of the bridge started to turn into an ‘M’ shape.

Image 4.2.5 shows the bridge failed at 3.9 kg.

Cause of failure:


In this structure, we’ve used pre-bend structure method to build it. Due to it’s a pre-bendstructure, during the constructing process the pre-bend component keep breaking as thefettuccine fragile properties. Although it’s hard but we’re still able to complete with thebending and came out with a pre-bend fettuccine bridge. Along the testing session, thebridge’s base that bended upward has been pulled by the load from the middle and causethe bridge to form ‘M’ shape.

4.3 Design 3 & 4

Image 4.3.1 shows the third and fourth design of our truss bridge

In our 3rd design and 4th design, we decided to repeat using bowstring truss bridge designwhere only the top chords are different. For 3rd design, the top chords are a series a shortermembers connected by vertical members to form a curve shape whereas the 4th design is atriangular top chord to experiment different possibilities with fettuccine as well as thedifference between the effectiveness of the different length of fettuccine when it is used astop chord. The distances between trusses are as the 2nd design where they increase steadilyby each truss from the middle.

Structure Analysis

Diagram 4.3.1 shows the force analysis of our third design

Bridge Details:


Clear Span: 850mm


Height: 130mm


Efficiency: 67.5

In design 3, we remove the bottom part of two sides, to try out whether the structure willhelp out supporting the bridge, and the truss is following our first design. For the bottomchord of the bridge, we are using straight structure for this design as we found out that usingcurve structure for the bottom chord is not effective. Unfortunately, the bridge failure isagain caused by the bottom chord.

Model Test

Image 4.3.2 shows the fettuccine bridge has been set up for testing and bottle with water asload.

Image 4.3.3 shows the bridge seems rigid after load has been added.

Image 4.3.4 shows the bridge started to bend to one side when the load reach 3.3kg.

Image 4.3.5 shows the bridge had collapsed at 3.6kg due to twisting and breaking apart.

Cause of failure:


This bridge goes well along the constructing process, the structure only have bending on thetop beam and flat base. In the process of testing, the bridge doesn’t show any sign ofbending and due to the load has been placed unevenly and cause the hock to move towardsone side and cause twisting then broke. After identify and verification, we’ve found out thatthe problem is with the base we’ve made was not strong enough.

Structure Analysis

Diagram 4.3.2 shows the force analysis of our fourth design

Bridge Details:


Clear Span: 850mm


Height: 200mm


Efficiency: 64.8

In design 4, we changed the bridge design into triangular structure; the truss arrangement isstill the same as previous bridges. We used the triangular top chord to test if the structurewill help supporting the load more efficiently than curved top chord structure. We areunable to get the result we want as the same problem still occurs, the midpoint of thebottom chord broke faster than other members.

Image 4.3.7 shows the bridge has been set up for testing and water as load.

Image 4.3.8 shows the bridge seems rigid and doesn’t show any sign of bending after loadhas been added.

Image 4.3.9 shows the bridge broke at the middle suddenly when the load reached 3.6kg.

Cause of failure:


We’ve building this bridge without using any pre-bend structure, the overall form of thebridge was a triangle. In the testing process, bridge is slightly similar to the previous onewhich doesn’t show any sign of bending and due to the load has been placed unevenly andcause the hock to move towards one side and cause twisting then broke. The problem alsowith the base of the bridge was still not strong enough.

4.4 Design 5 & 6

Image 4.4.1 shows the fifth and final design of our truss bridge

For our last design approach, using all the data and analysis that we have gathered, weunderstand that the height of the whole bridge should be reduced to increase effectiveness.The whole bridge is designed to be more flat-out than all the previous ones. Also the middlepart where load is being hung must serve the function to distribute force as equallythroughout the entire bridge span rather than just depending on the trusses.

Structure Analysis

Diagram 4.4.1 shows the force analysis of our fifth and final design

Bridge Details:

Weight of the bridge: 155g / 165 g

Clear Span: 850mm


Height: 200mm

Maximum Load Capacity: 5.9kg / 5.0 kg

Efficiency: 224.6 / 151.5

In this design, we reduced the height of the bridge, reducing the weight to increase theefficiency. Due to the same failures from our previous experience, we found out that the topchords did not actually help much in carrying the loads, as the bottom chords are the mainload carries, so we enhance the bottom chord by using I-beam structure, three layers offettuccine in the middle and one layer in both ends.

Model Test

Image 4.4.2 shows the fettuccine bridge has been set up for testing. Water poured intobucket.

Image 4.4.3 shows the bridge is stable during the test.

Image 4.4.4 shows the bridge doesn’t affect by the load but the part that supporting theload started to bend.

Image 4.4.5 shows the part that hold the load broke but the whole structure remainunharmed. The load is 4.9 kg. Second test after replacing the supporting part and it reach5.5kg.

Cause of failure:


This bridge has been constructed without using any pre-bend just, an evolve product ofmock-up 4. At first we lack of confident toward this bridge which is supposed to be the final,so we came out with an idea of testing it as mock-up no.5. Everything goes well in the wholeprocess of testing, the structure is very rigid but only the part that act to hold the loadbroke. After replace with a better one we went for 2nd test, we’re all satisfied with theoutcome.

Model Test (Final Design)

Image 4.4.6 shows the bridge was evolve of design 5 has been set up for the final load test.

Image 4.4.7 shows the bridge remain stable throughout the test.

Image 4.4.8 shows the bridge fail due to twist at the end of bridge. The load is 5kg.

Cause of failure:

This bridge was actually a rebuild of the mock-up no.5, we spent then whole night constructit. Due to all the classes and work in the afternoon we’re all tired. The bridge is slightlybended due to lack of workmanship. During the final load testing, the table surface wereslightly unbalance. The testing process go well and the bridge end up fail by twisting, butwe’re still contented with the outcome.

The following table concludes each design efficiency:

WEIGHT LOAD EFFECIENCY

Design 1 246 g 3.3 kg 44.3

Design 2 186 g 3.9 kg 81.8

Design 3 192 g 3.6 kg 67.5

Design 4 200 g 3.6 kg 64.8

Design 5 155 g 5.9 kg 224.6

Design 6 165 g 5.0 kg 151.5

Table 4.4.1 shows the efficiency of each bridge.

5.0 ConclusionIn this project, we managed to understand tension and compressive strength that is highlydepending on the materials. On the other hand, we are also able to understand how loadsare distributed through trusses. Through trials and errors, we were able to test out newstructure by playing around with different design of trusses. Unfortunately, load distributionsof the model were not performing well due to random errors from workmanship issues andetc. In our opinion, the usage of fettuccine as material is not a good choice because everypack of fettuccine contain random amount of fettuccine that are suitable for use and thequality of it varies from each other. After this project, we also felt that a lot food is wastedespecially when there are 100 over students doing this project. We believe there are modelmaking materials that are more suitable for this project especially when fettuccine ismanufactured as food not as modelling material.

Source: Chatelaine

7.0 Appendix

7.0 ReferencesHanks, M. (2013, September 19). SunThisweek | Bike-pedestrian bridge to be rehabilitated

to link Bloomington to Dakota County. Retrieved from

http://sunthisweek.com/2013/09/19/bike-pedestrian-bridge-rehabilitated-link

bloomington-dakota-county/

James, B. (n.d.). Bridgehunter.com | Long Meadow Bridge. Retrieved from

http://bridgehunter.com/mn/hennepin/3145/

John A. (2011). Long Meadow Bridge, Eagan, MN. Retrieved from

http://www.johnweeks.com/bridges/pages/b09.html

Mike H. (2014, July 3). Sun Current | A glimpse into the future of the Old Cedar

Avenue Bridge. Retrieved from http://current.mnsun.com/2014/07/a-glimpse-into

the-future-of-the-old-cedar-avenue-bridge/

Long Meadow Bridge. (n.d.). Retrieved from

http://www.nps.gov/nr/feature/places/13000324.htm

http://sunthisweek.com/2013/09/19/bike-pedestrian-bridge-rehabilitated-link

http://current.mnsun.com/2014/07/a-glimpse-into

http://www.johnweeks.com/bridges/pages/b09.html

http://bridgehunter.com/mn/hennepin/3145/

Art & Photos

Fettuccine bridge Full report