Project 1 fettucine truss bridge

Chew Woan Chyin 0310797

Kristine Yong 0311297

Toh Chee Cheng 0311122

Yap Zhi Jun 0310738

Yap Zhong Lin 0310557

TAYLOR'S UNIVERSITY LAKESIDE CAMPUS

Schools Of Architecture Building & Design

Building Structures [ARC 2522]

Project 1: Fettuccine Truss Bridge

Table of Content

1. Introduction 1- 3

1.1 General Purpose of Project

1.2 Aim of Study

1.3 Objectives

1.4 Project Overview

1.5 Working Schedule

2. Methodology 4 - 5

2.1 Precedent Study

2.2 Material Testing & Equipment Preparation

2.3 Model Making & Design Development

2.4 Structural Analysis

3. Precedent Studies 6 - 10

3.1 History & Background

3.2 Pennsylvania (Petit) Truss Span

3.3 Structures & Functions

4. Materials & Equipment

4.1 Materials Used

4.2 Equipments Used

4.3 Model Making Process

5. Bridge Test

5.1 Bridge Test 1

5.2 Bridge Test 2

5.3 Bridge Test 3

5.4 Bridge Test 4

5.5 Bridge Test 5

11 - 17

18 - 28

6. Final Bridge 29 - 38

6.1 Bridge Design

6.2 Bridge Making Process

6.3 Bridge Joints

6.4 Final Bridge Testing

6.5 Truss Analysis

7. Learning Outcomes 39

8. Conclusion 40 - 41

9. References 42 - 43

10. Appendix 44 - 49

10.1 Case Study 1

10.2 Case Study 2

10.3 Case Study 3

10.4 Case Study 4

10.5 Case Study 5

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1. Introduction

1.1 General Purpose of Project

1.2 Aim of Study

1.3 Objectives



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1.1 General Purpose Of Project

Truss is a structure built up of three or more members which are

normally considered being pinned and hinged at the joints. The following

figure shows different types of trusses. Load applied to the truss is transmitted

to joint so that each individual members are in either pure tension or

compression.

1.2 Aim Of Study

In this project, we were to design a fettuccine bridge with the

requirements of a clear span of 750mm and a maximum weight of 200g. It is

to construct a bridge with high efficiency with minimal material weight and

high load.

1.3 Objectives

It is to develop the understanding of construction materials in both

tension and compressive strength. Furthermore, it helps us to develop the

understanding of a truss in force distribution to have a perfect truss bridge

design with high level of aesthetic value and minimal construction material.


This report begins with precedent study to understand on how the

design of a truss bridge affects the compression and tensile strength to

withstand loads and the construction methods. In a group, we are required to

design and construct a fettuccine bridge of 750mm clear span and maximum

weight of 200g. We use AutoCAD to generate our truss in order to get the

dimension accurate and balance. Content of this report include methodology

and various truss bridge design which were analysed, observed and

documented every attempt to test the efficiency, prior conclude on a final

design. Load testing on different bridges were carried out and documented in

various way for instance record manually, taking photo and video recording. A

set of analysis regarding the strength of the bridge structure and the reason of

failure has been record. Discussion and suggestion concerning the

improvement of the bridge are included in this report. At the end of this report,

the understanding of truss bridge construction is shown through individual

case study.

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Date Work Progress

06/04/2015 Planning and distributing works

11/04/2015 Researching and planning on which truss design to construct

13/04/2015 Testing of tensile and compressive strength of fettuccine by

using 1, 2, 3, 4 and 5 layers and using I-beam design.

14/04/2015 Making the first model and testing the first model

17/04//2015 Making the second model and testing the second model

24/04/2015 Making the third model and testing the third model

25/04/2015 Making the fourth model and testing the fourth model

26/04/2015 Making the fifth model and testing the fifth model. Final truss

bridge model making session. Refining the bridge model

27/04/2015 Final submission and load testing for fettuccine bridge

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2. Methodology

2.1 Precedent Study




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2.1 Precedent Study

To research for a truss bridge and study on its connections, arrangement of

members and orientation of each member. Research is taken from the source

of internet and books. The fettuccine bridge will be designed and construction

based on the information of the precedent study.


Exploration on the materials used in term of its strength by different types of

testing. Data showing the fettuccine strength results in different circumstances

is rerecorded in the subtopic of material under the topic, Analysis. Equipment

is prepared before the testing of truss bridge.


The fettuccine bridge is designed in AutoCad and is printed out to scale for

model making. Jointing of the fettuccine bridge will be discussed under the

topic of truss analysis.

Requirements of fettuccine Bridge:

750mm clear span bridge

Maximum weight of 200g

Only fettuccine glue can be used

The bridge will be tested to fail

The strength of the model will be maintained and the weakness will be

eliminated for further development.


Structure model is analyse to shoe the understanding of the truss and its load

transfer system. Failure models are analysed to discover the problem and the

analysis is the reference to the next model bridge. Structural analysis is the

determination of the effects of load on the fettuccine bridge and its members

by calculation.

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3. Precedent Studies

3.1 History and Background


3.3 Structures and Function

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Nanticoke Bridge, Luzerne County, Pennsylvania

3.1 History and Background

This bridge consists of two large pin-connected Pennsylvania through

truss spans and a slightly smaller truss that is a combination of a

Pennsylvania and a Parker truss with multiple connection types. The truss

spans are all at the northernmost end of the bridge. The southern end of the

bridge has a long approach system. The original approach system was

demolished a number of years ago and replaced with modern pre-stressed

concrete spans. As such, the approach spans are no longer historically

significant. However, the truss spans alone should be considered to have

historic and technological significance. The remainder of this narrative will

discuss the truss spans only.

This bridge is a rare surviving example in Pennsylvania of a large pin-

connected truss bridge. Pin-connected truss bridges once carried many of

Pennsylvania's highways over the large rivers in the Commonwealth. At one

time, Pennsylvania was one of the few states with a sizable population of pin-

connected truss bridges crossing large rivers. Unfortunately, nearly all have

been demolished or are in imminent danger of demolition. This bridge is thus

today distinguished as rare. Similarly, bridges with a Pennsylvania truss

configuration are, perhaps ironically, today extremely rare in Pennsylvania,

again due to widespread demolition.

Despite carrying a relatively high volume of traffic, the bridge appears

to retain good historic integrity with no major alterations to the overall design

and materials of the truss superstructure. This bridge should receive an

extremely high preservation priority.

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3.2.1 Overview

Sometimes called the Petit truss. Designed by the Pennsylvania railroad, this

configuration combines the engineering ideas behind the Baltimore with those

of the Parker or Camelback.

3.2.2 Forces

The chords and members of a truss bridge experience strain in the form of

tension (stretching apart) and compression ( squeezing together). Engineers

often picked different types of materials and designs for the different parts of

bridge based on these forces.

Figure 3.1: Pennsylvania (Petit) Truss

Figure 3.2: Baltimore Truss Reaction Force

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3.3 Structure and Function

Trusses spans normally have a truss configuration that is symmetrical.

However, this truss span is asymmetrical in its configuration. The northern

truss span has ten "primary" panels. At first glance, it may appear that the

primary panels on the northern half of the span are subdivided, following the

Pennsylvania truss configuration, while the southern half is not subdivided

and instead follows a Parker truss configuration. In addition, the northern end

post gets additional support not given to the southern end post with the

inclusion of a vertical and diagonal member that connect to the mid-point of

the end post. Another extremely bizarre aspect of the bridge is the southern

six panels of the truss have a bottom chord that is an eye bar, while the

remaining northern panels all have an unusual, massive, riveted, built-up box

beam. The asymmetry of the bottom chord aligns with the asymmetry of the

truss configuration, which is no coincidence. This box beam bottom chord is

riveted, although note that portions of the bottom and inside face of the beam

have been altered with modern bolts present, apparently as part of a floor

beam alteration,

Another oddity of the bridge is that all of the diagonal members on the bridge are built-up beams except for two diagonals on each truss web, which are eye bars instead. This however is a symmetrical detail and while an unusual detail, does not appear to have anything to do with the above asymmetrical details.

Figure 3.3: Bridge Structure Component

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The 24 span, 1,922'-long bridge consists of three, 263'-long,

Pennsylvania thru truss spans built in 1914, and 21, 54'-long, prestressed

concrete box beam approach spans built in 1987. The pin connected truss

spans are traditionally composed of built up compression members and eye

bar tension members. The northernmost span has been altered by

replacement of the lower chord eye bars with steel channels and replacement

of the pin connections with bolt connections at the lower panel points. The

Pennsylvania truss, a variation of the Pratt truss with subdivided panels and

polygonal top chord, was developed by bridge engineers of the Pennsylvania

RR about 1875. This example has no unusual or noteworthy features. It is a

late example of its type/design that has been altered. Earlier and more

complete examples have been identified. The bridge is not historically or

technologically distinguished by its setting or context.

Figure 3.4: Details of Truss Connection and Members

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4. Materials & Equipment

4.1 Materials Used

4.2 Equipments Used

4.3 Model Making Process

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4.1 Materials

4.1.1 Fettuccine (Main material)

As stated in the brief, fettuccine is the only material used for the model.

We aim to achieve a high level of aesthetic value and use minimal

construction material to achieve high efficiency.

The tensile and compressive strength of fettuccine were studied and

tested. Before testing, the most suitable fettuccine strips to be used for our

model was determined by methods below.

a. Methods:

Strips of fettuccine were laid on a flat surface

Load was placed to test the rate of buckling

Time taken until failure was measured in order to determine the

strength & flexibility of the fettuccine

Steps were repeated with a different brand

c. Testing Strength of Fettuccine

The table (Table 1) below shows the strength of each fettuccine analysed by

applying point pressure on the middle. Different numbers, orientation and

arrangements of fettuccine were used to form the members.

Clear

Span

(cm)

Length of

Fettuccine

(cm)

Quantity

(Sticks)

Weight sustained (kg)

Horizontal Vertical

15 25 1 0.1 0.1

15 25 2 0.2 0.2

15 25 3 0.5 0.7

15 25 4 1.3 1.5

15 25 5 1.4 1.7

Table 4.1: Strength of each fettuccine analysed by applying point pressure on the middle

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Figure 4.2: When the fettuccine is loaded by forces, stress and strains are created throughout

the interior of the beam

Conclusion:

The strength of one fettuccine appears to be lower when faced

horizontally than when it is faced vertically from 1 stick to 5 sticks. In conclude,

the greater the area exposed relative to its volume, the weaker the fettuccine

member is in resisting strains and stresses. From the result, we decided to

use fettuccine of 1 to 5 sticks with vertical facing on the truss member that

required less strength.

d. Testing Tensile and Compressive Strength of Fettuccine

The table (Table 1) below shows the tensile and compressive strength of each

fettuccine analysed by applying pressure. Different numbers of fettuccine

were used to form the members.

Quantity

(stick)

Weight sustained (kg)

Tension Compression

1 0.95 0.45

2 1.95 1.50

3 3.03 2.70

4 3.09 2.65

5 3.93 3.45

Table 4.3: Tensile and compressive strength of each fettuccine analysed by applying

pressure

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Conclusion:

After conducting the testing on fettuccine, we conclude that fettuccine is capa

ble in with-standing tension force, while weak in withstanding compression

force.

e. Testing on Single Member

Figure 4.4: I-Beam

Image Testing tensile strength by using

from 1 strips to 5 strips.

Image Testing compressive strength

by using from 1 strips to 5 strips.

Strength: Very Strong

This design is most preferable in terms of efficiency. 'I'

beam structure is use both advantages of horizontal

and vertical position are able to be put in use. When the

vertical member is placed in between two horizontal

members, the horizontal members will enhance the load

distributions and the load will transfer to the vertical

member which can withstand more loads.

Figure 4.5: Layering

Strength: Not so strong

This is an effective design with minimal human error

and also reduce the weight of the model

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4.1.2 Glue (Adhesive material)

Exploration on several types of glue to determine which one is suitable as the

adhesive material in term of efficiency for the model.

Efficiency

Ranking

Types of Glue Observation & Description

1

3-seconds Glue

High efficiency

Fastest solidify time

Lighter in weight

2

Elephant Glue

High efficiency

Longer solidify time

Lighter in weight

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4.2 Equipments Used

Materials that helped us throughout fettuccini bridge's assignment:

S-Hook & Raffia String

Serves as a connection between

the fettuccine bridge and the

bucket.

Bucket

A vertical cylinder with an

open top, used to carry both

liquids and solids, aiding in

the load distribution

process.

Weighing machine

A weighing machine as

weigh the weight of model

bridge and loads.

Bottles & Weight Plates

Bottles and weight plates are used

load which were very easy to

handle. Remark that 100ml is equal

to 100 grams.

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4.3 Making Model Progress

1. Selecting fettuccini which

able to lay on a flat surface

3. Smoothing the angle of

the fettuccini by using

sandpaper

2. Cutting fettuccini by

following the 1:1 scale 2D

model

6. Connecting two facades of

the bridge together

4. Joining members on the

paper with the 2D model

5. Adding in the waffle

which can transfer load

more efficiency

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5. Bridge Test

5.1 Bridge Test 1

5.2 Bridge Test 2

5.3 Bridge Test 3

5.4 Bridge Test 4

5.5 Bridge Test 5

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Truss Type: Howe Truss

Height (At Highest Point) : 84 mm

Width: 84 mm

Length ( Top Chord) : 504 mm

Length ( Bottom Chord): 840 mm

5.1 Bridge Test 1

Side

Top

w

Elevation

Elevation

Elevation

Base

w

Top View

Elevation

Elevation

Elevation

Top View

Elevation

Elevation

Elevation

Top View

Elevation

Elevation

Elevation

Weight: 0.262 kg

Maximum Load: 2.7 kg

Clear Span: 750mm

Efficiency, E:

E

E

E

Figure 5.2: Shows the side, top and base of the 1st bridge with dimension

Figure 5.1: Shows photos of 1st

bridge.

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Analysis:

First truss bridge that we done was Howe Truss Bridge. It was inspired by the first precedent

studies that we have done based on The Fair Oaks Bridge. The Fair Oaks Bridge have Pratt

trusses includes vertical members and diagonals that slope down towards the centre. Thus, we

modify and change it to Howe Truss that diagonals member slope down towards the both side

of the bridge. This is because it can withstand compression force of the load. Furthermore,

fettuccine is a type of material that is stronger in tension, and weaker in compression.

Bending can be observed at the top chord of the

bridge after 1kg of load exerted on the bridge.

More bending and slight bending can be observed

at the top chord and bottom chord of the bridge

respectively after 2kg of load exerted on the

bridge.

The bridge weigh 0.262kg can carry load up to

maximum 2.7kg until it breaks into half.

Conclusion:

As a conclusion, the construction of the base is not strong enough to carry load exerted. This is

because of the poor workmanship of the bridge, each members of the joints are not joint

together properly. Furthermore, gluing method of the fettuccine is not appropriate as, not the

whole piece of fettuccine if filled with glue. Thus, holes created weaken the load distribution.

Load Tension

Figure 5.3: Shows truss analysis of 1st bridge

Compression

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Truss Type: Pennsylvania Truss

Height (At Highest Point) : 200mm

Width: 100 mm

Length ( Top Chord) : 240mm


5.2 Bridge Test 2

Side

Base

w

Top View

Elevation

Elevation

Elevation

Top View

Elevation

Elevation

Elevation

Top View

Elevation

Elevation

Elevation

Top

w

Elevation

Elevation

Weight: 0.270 kg


Clear Span: 750mm

Efficiency, E:

E

E

E

Figure 5.5: Shows the side, top and base of the 2nd bridge with dimension

Figure 5.4: Shows the photos of 2nd

bridge.

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Analysis:

Load

Tension

Figure 5.6: Shows truss analysis of 2nd bridge

Compression

To address this issue faced in test 1, we started looking at subclasses of Pratt Truss, we then

stumbled upon the Pennsylvania Truss. A Pennsylvania Truss has additional bracing in the lower

section of the truss to prevent buckling in the compression members and to control deflection.

Pennsylvania Truss differs by the addition of half-length struts or ties in the top, bottom, or both

parts of the panels. It provides extra support around the centre of the slanted braces and will

prevent buckling in the compression member. Thus, it introduces more tension members into

the bridge, which is an advantage to our model as fettuccine is stronger in tension.

Slight bending can be observed at the

top chord and bottom chord of the

bridge respectively after 0.5kg of load

exerted on the bridge.

The bridge weigh 0.270kg can carry load

up to maximum 1.2kg until it breaks into

half.

Conclusion:

After the testing, the bridge broke near the centre of the bridge. Due to the height of the bridge

was too high which has the heaviest load, the forces did not spread out to another side. Thus,

the failure of this bridge was also identified as workmanship effort. Some of the selected

fettuccine were bit twisted which made a gap in between.

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Height (At Highest Point) : 105mm

Width: 85 mm

Length ( Top Chord): 340 mm


Weight: 0.202 kg


Clear Span: 750mm

Efficiency, E:

E

E

E

5.3 Bridge Test 3

Side

n

Top

w

Elevation

Elevation

Elevation

Base

w

Top View

Elevation

Elevation

Elevation

Top View

Elevation

Elevation

Elevation

Figure 5.8: Shows the side, top and base of the 3rd bridge with dimension

Figure 5.7: Shows the photo of 3rd

bridge on weighing scale.

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Since the issue faced from test 2 was due to height of model bridge, we reduced the half of the

height from 200mm to 104mm. Besides, we reduced the width of each bracings. The adjusted

bracings and members were made to enhance the force spreading to the rest of the bridge.

Thus, to further strengthen the bridge, we decided to reduce down fettuccine layers on the both

side bracings which transfer less load. By reducing the weight of bridge, the forces could spread

more evenly.

Analysis:

Load Tension

Figure 5.9: Shows truss analysis of 3rd bridge

Compression

No bending can be observed at the top

chord of the bridge after 1kg of load exerted

on the bridge.

No bending can be observed at the top

chord of the bridge after 1kg of load exerted

on the bridge.

The bridge weigh 0.202kg can carry load up

to maximum 3.0kg until it breaks into half.

Conclusion:

After the testing, the bridge did not break except the load carried member. This time, the forces

at the centre could not spread out to another sides. So, we decided to change the single load

centre member to waffle slab.

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Width: 55 mm



Weight: 0.212 kg


Clear Span: 750mm

Efficiency, E:

E

E

E

5.4 Bridge Test 4

Side

n

Top

w

Elevation

Elevation

Base

w

Top View

Elevation

Elevation

Elevation

Top View

Elevation

Elevation

Elevation

Figure 5.11: Shows the side, top and base of the 4th

bridge with dimension

Figure 5.10: Shows the photos of 4th

bridge.

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Analysis:

Based on the previous failure on the bridge, we have made some amendment on the design to

allow the better load distribution at the base. Waffle slab has been implemented at the base

which span 130mm from centre to the side to ensure more load to carry at the centre. As more

load is exerted at the centre then spread to the side. Also, load is to evenly distribute to both I –

beam at the base, which act as the main frame for the bridge.

The steel pail itself weigh 2.115kg. Thus, the bridge

starts with 2.115kg load. No changes on the

trusses have been observed on the bridge.

No changes on the trusses have been observed on

the bridge after 3.115kg has been exerted on the

bridge.

Initially, no changes has been observed on the

bridge. However, the bridge breaks in a sudden

after 4.2 kg load exerted on the bridge. We

observed that the waffle slab at the base breaks

into half, some splits have been observed at the

members nearby the waffle slab.

Conclusion:

As a conclusion, the load distribution is still not ideal. As the truss only breaks at the centre,

which is a result of uneven load distribution. This is because the load is centralized at the centre

which cased it unable to spread along the base to the table. The weakness of the bottom part of

waffle slab causing the upper member of waffle slab to fall when the bottom breaks and thus

failed to sustain higher load.

Load

Tension

Compression

Figure 5.12: Shows truss analysis of 4th

bridge

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Weight: 0.202 kg


Clear Span: 750mm

Efficiency, E:

E

E

E



Width: 55 mm



5.5 Bridge Test 5

Top

w

Elevation

Elevation

Elevation Base

w

Top View

Elevation

Elevation

Elevation

Top View

Elevation

Elevation

Elevation

Top View

Elevation

Elevation

Elevation

Side

n

Figure 5.13: Shows the side, top and base of the 5th

bridge test with dimension

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Analysis:

Based on the previous failure on the bridge, we have made some amendment on the design

to allow the better load distribution at the base. In the previous test, waffle slab has been

used. So, we replace it with pencils to test on the maximum load that the bridge is able to

carry when higher strength of material is used.

Conclusion:

As a result, the 5th bridge is the bridge design that we satisfy the most, because the load is

able to distribute equally. Thus, we decide to build the final bridge refer to the 5th bridge’s

trusses, with a slight amendment on the design and emphasize on the way to strengthen the

bridge in the same time reduce weigh. Which is not to exceed 200g.

This test is not recorded in video. The

bridge able to carry up to 6.5kg until it

breaks. This has effectively increase the

efficiency of the bridge. In the end, the

entire bridge breaks into half which shows

that the load distribute is equal at both

side of the bridge.

Load

Tension

Compression

Figure 5.14: Shows truss analysis of 5th

bridge

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6. Final Bridge

6.1 Bridge Design


6.3 Bridge Joints


6.5 Truss Analysis

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Truss Type

Height (Highest point)

Width

Length (Top Chord)

Length (Bottom Chord)

Weight

Maximum Load

Clear Span

Efficiency, E

: Pennsylvania Truss

: 80 mm

: 50 mm

: 780 mm

: 860 mm

: 0.197 kg

: 6.870 kg

: 750 mm

= 239.58

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6.1 Bridge Design

Figure 6.1 shows the side, base & top of the final bridge with labelling of bridge components.

Problems faced from 5th bridge :

1. Middle part is not strong enough to carry stronger load. (Only load carry

points break, but not the whole bridge breaks)

2. Overweight, more than 200g which do not meet the project requirement.

Solution and Improvement :

1. We decide to use stronger and longer waffle structure (3) for the load

carry points (middle part).

Waffle structure (Figures shown in Model Making Process)

1st layer : 3 layers fettuccine placed vertically

2nd layer : 3 layers fettuccine placed vertically in opposite direction

3rd layer : 3 layers fettuccine placed vertically same direction with the 1st

layer

2. To reduce the weight of the fettucine, we reduce the diagonal bracing (1)

at the last two parts of the bridge, we also reduced the vertical diagonal

bracing (2) of the bridge from 4 to only 2 parts have it.

1 1

2 2

3

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1 Layer

2 Layers

3 Layers

I-Beam

1

2

3

1. 3.

2.

Top Chord of the bridge with 3 layers of

fettuccine. Curve the fettucine when glue

it together to make a curve Top Chord.

Sectional view of Bottom

Chord (I-Beam) with one layer

one top and bottom and three

layers in between.

Load Carry Member

Figure 6.2 shows the number of layers of fettuccine used for different component in the bridge.

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2. Then, we proceed with the

Top Chord (curved part).

1. Firstly, we starts with the Bottom

Chord (I-Beam).

3. After that, the Vertical members of

the sides are added.

4. Then, we add the Diagonal

Bracing of the sides of the

bridge.

5. Next, the bottom beams are added

except the middle part.

6. Next, the middle beams (3

layers) are added in vertical

direction.

Three longer and stronger layers of waffle structure for more equal load

distribution. Three layers of fettuccine stick together and placed vertically. The

load carry members have more layers compare with other members.

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7. Then, another longer beam (3

layers) are added in opposite

direction.

8. To increase the load carry

points, beams (3 layers) are

added.

9. To make the load carry points

stronger, we added another

layer of beam (3 layers).

10. After that, both sides are

connected together.

11. The last part is adding the

Strut and Top Lateral

Bracing on top of the bridge.

12. Finally, the final bridge is done.

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6.3 Bridge Joints

Part 1

Part 2

Part 3

Part 1

Part 2

Part 3

1

2

3

4

5

6

7

8

1. Join on top of the member

- Vertical Member join in between Top Chord

and Bottom Chord

2. Cut and join

- Diagonal bracing cut precisely according to

drawing and join with other members (to

make sure load transfer in accurate way)


- Diagonal bracing are cut and join in

between the Top Chord and Bottom Chord

with no overlapping joints


- Strut stack on the Top Chord

5. Cut and join, Stack on the member

- The Strut and Top Lateral Bracing cut

and join together then using stack

method to join with Top Chord

6, 7, 8 Stack on top of the member

- Waffle structure are stack on top

of the Bottom Chord with

different layers

- 1st layer, Beam (6)

- 2nd layer, Longitudinal Beam (7)

- 3rd layer, Shorter Beam (9)

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1 – 2 kg

The bridge still in stable mood.

3 – 4 kg

From the picture, the load

start pulling our bridge

downwards. So far, no

obvious unstable joint

members.

5 – 6 kg

The middle part of the bridge

start to pull more downwards

when more load is putting in.

The top right hand side of the

bridge unstable and bend.

6.9 kg

The bridge breaks at the very

end of the right side of the

bridge.

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6.5 Truss Analysis

Figure 6.3 shows the truss analysis of the final bridge with tension and compression.

Figure 6.4 shows the connection of bridge and water pail (load) with string and S hook.

Failure reason:

1. Breaking point at the right end side of the bridge means load is not

distributed equally throughout the whole bridge. Main problem will be the

tying method that connect the bridge to the point load is not same length

which affected the load distribution. (Figure 5.4)

2. From last bridge changes, to reduce the weight of the bridge, the diagonal

bracings at the both end part are taken out. This affect the strength of the

bridge especially the tension strength. So, this is part of the reason the

bridge breaks at the end part.

3. Workmanship problem. Fettuccine is a building material which need a lot

of patient and very precise when cutting and joining it because it has

different thickness and easy to break. So, workmanship is one of the

problem that affect the bridge to sustained maximum load.

Load

Tension

Compression

Breaking Point

Not appropriate tying

method of the string

causes load distributed

not equally.

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Analysis of changes from last bridge:

Good

Reduce the vertical diagonal bracing of the bridge which is not very effective in

transferring load in the bridge. This can help to reduce the weight of the bridge.

Change the method of constructing the waffle structure which is more stable and

stronger. Three layers of waffle structure with strong load carry member.

Bad

To reduce the weight of the bridge, the both end part of the diagonal bracings are

reduced. But this weaken the strength of the bridge especially when the load

distributed to the bridge until the end part.

Solutions:

1. To overcome the load distribution problem, we should use equal length of

string which can distributed the load equally. We also should use another

better tying method to connect the bridge with the load.

2. To overcome the strength problem, we should add diagonal bracing at the

both end of the bridge so that the bridge can withstand more tension

strength.

3. To maximize load sustained in the bridge, workmanship skill is very

important. To produce an effective bridge, precision in measurement and

workmanship skill should improve.

Conclusion:

For all the bridges tested, final bridge has the highest efficiency. This proved that

all the improvement and changes we made are correct and can improve more.

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7. Learning Outcomes

The learning outcome of this project is enable us to evaluate, explore and

improve attributes of construction materials. Besides that, it allows us to explore and

apply understanding of load distribution in a truss and able to evaluate and identify

tension and compression members in a truss structure. After analyse and built the

truss using fettuccine, we can explore different arrangement of members and design

in a truss structure.

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8. Conclusion

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At the end of this project, we had constructed a total of 6 fettuccine bridges

and experimented on the efficiency of withstanding loads. The precedent study we

chose to study on is Nanticoke, Pennsylvania which uses Pennsylvania truss in the

arrangement. We also concluded our final design by using Pennsylvania truss as this

achieve both aesthetic value and efficiency design. The triangle bracing minimize

the forces to only compression and tension. When load is applied to the bridge,

sometimes the forces of components switch from compression to tension especially

those near to the centre of the bridge, to increase the efficiency in load distribution.

We managed to achieve the highest efficiency in our final testing among all of

the bridges we had done. Our final fettuccine bridge with a total weight of 297g,

achieved an efficiency of 239.58% which withstand a total load of 6.9kg. In this task,

we are able to understand the load distribution in a structure and the calculation of

type of force applying in each structure member. It is very crucial for us to

understand how each of the member works together as a whole in a structural

system to attain a higher efficiency.

Besides that, we attempted to achieve highest accuracy measurement of

each truss member as we generated the truss by AutoCAD and printed out as

reference. We also take in a few consideration concerning the construction of bridge

until the final stage of load testing. During the design, we trying to reduce the

quantity of fettuccine and increase the durability to attain higher efficiency. In the

process of making we also realised the sequence of doing partly will affect the time

and the strength in between fettuccine and adhesives. Moreover, work delegation

and time interval between completion of bridge and load testing will be affect due to

the efficiency of completing on time and sufficient time for the adhesives to dry and

maintain its strength until load testing.

To conclude, it a great task for us to hands-on experience in a group to make

us more understand and analyse the structure of a truss. By using something that we

usually will come into contact but in a different way of experience gain us knowledge

and amazed us how tough a structure can be. As we are involve in this industry, we

have to think critically and be more attentive to the details of a structure that can

function efficiently for safety and wellbeing of the people.

Test Types of Truss Load (kg) Weigh (kg) Efficiency

1st Howe 2.700 0.262 27.82

2nd Pennsylvania 1.200 0.270 5.33

3rd Pennsylvania 3.000 0.202 44.55

4th Pennsylvania 4.200 0.212 83.21



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9. References

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Ammann, O. (1917). The Hell Gate arch bridge and approaches of the New York connecting railroad over the East River in New York City. New York: [American Society of Civil Engineers]. Bridge Design Contest | Presented by Engineering Encounters. (n.d.). Retrieved April 30, 2015, from http://bridgecontest.org/ Design of a highway truss bridge, design of a railroad truss bridge, wooden bridges, roof trusses, bridge piers and abutments, bridge drawings. (1923). Scranton, Pa.: International textbook. Mystery Bridge 35: Deck Pennsylvania Petit truss bridge in Wisconsin. (2013, December 9). Retrieved May 2, 2015, from http://thebridgehunter.areavoices.com/2013/12/09/mystery-bridge-35-deck-pennsylvania-petit-truss-bridge-in-wisconsin/ Nanticoke Bridge. (2011, April 5). Retrieved May 1, 2015, from http://historicbridges.org/bridges/browser/?bridgebrowser=pennsylvania/nanticoke/ Pennsylvania truss. (n.d.). Retrieved April 29, 2015, from http://bridgehunter.com/category/tag/pennsylvania-truss/page3/ Remember. (n.d.). Retrieved May 3, 2015, from http://www.nanticokecity.com/remember.htm Vanvelet, H. (1887). Truss Analysis. In Bridge calculations. Place of publication not identified: [publisher not identified].

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10. Appendix

10.1 Case Study 1

10.2 Case Study 2

10.3 Case Study 3

10.4 Case Study 4

10.5 Case Study 5

Documents

Project 1 fettucine truss bridge