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
1.4 Project Overview
1.5 Working Schedule
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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.
1.4 Project Overview
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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1.5 Working Schedule
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
2.2 Material Testing & Equipment Preparation
2.3 Model Making & Design Development
2.4 Structural Analysis
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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.
2.2 Material Testing & Equipment Preparation
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.
2.3 Model Making & Design Development
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.
2.4 Structural Analysis
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
3.2 Pennsylvania (Petit) Truss Span
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 Pennsylvania (Petit) Truss Span
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
Length ( Bottom Chord): 1027 mm
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
Maximum Load: 1.200 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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Truss Type: Pennsylvania Truss
Height (At Highest Point) : 105mm
Width: 85 mm
Length ( Top Chord): 340 mm
Length ( Bottom Chord): 840 mm
Weight: 0.202 kg
Maximum Load: 3.000 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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Truss Type: Pennsylvania Truss
Height (At Highest Point) : 85 mm
Width: 55 mm
Length ( Top Chord) : 780 mm
Length ( Bottom Chord): 860 mm
Weight: 0.212 kg
Maximum Load: 4.200 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
Maximum Load: 6.500 kg
Clear Span: 750mm
Efficiency, E:
E
E
E
Truss Type: Pennsylvania Truss
Height (At Highest Point) : 85 mm
Width: 55 mm
Length ( Top Chord) : 780 mm
Length ( Bottom Chord): 860 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
6.2 Bridge Making Process
6.3 Bridge Joints
6.4 Final Bridge Testing
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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6.2 Bridge Making Process
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)
3. Join on top of the member
- Diagonal bracing are cut and join in
between the Top Chord and Bottom Chord
with no overlapping joints
4. Join on top of the member
- 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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6.4 Final Bridge Testing
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
5th Pennsylvania 6.500 0.202 209.16
6th Pennsylvania 6.870 0.197 239.58
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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
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