2. CHAPTER 1:
INTRODUCTION
1.0 Introduction
1.1 Project Intention and Requirement
In a group of 6 members, we were required to design and construct a fettuccini truss
bridge with a clear span of 350mm and maximum weight of 70g. In order for the bridge to
be Efficient it is important to minimise the weight and maximise the load thus using the
least material to sustain the greatest possible load.
1.2 Aim of the Project
The aim of this project is to design a fettuccini truss bridge that utilises a perfect truss
design with high efficiency and minimal use of construction materials. Furthermore, this
project will develop an understanding of material tension and compressive strength as
well as develop an understanding of force distribution in a truss.
1.3 Report Overview
This report is a compilation of our understanding and analysis based on the precedent studies
conducted, construction method and the design of our truss bridge. The report started off with
the precedent studies of Pratt Truss and analysis of our designed truss and tests. Sets of testing
results and development of our designated bridge through several trial, error experiments and
failure analysis were recorded and included to the report. The analysis of the strength of the
bridge during the tests was also recorded to improve the efficiency of the bridge. The end of the
report will be the calculations of the individual case studies.
1.4 Learning Outcomes
By the end of this project, students will be able to:
Evaluate, explore and improve attributes of construction materials.
Explore and apply understanding of load distribution in a truss.
Evaluate and identify tension and compression members in a truss structure.
3. Explore different arrangement of members in a truss structure.
CHAPTER 2:
METHODOLOGY
2.1 Precedent Study
For the first step of the project, we decided to do a precedent study on our chosen truss
which is the Pratt truss. From the precedent study, we analysed how the structure works
in real life and try to imply the same principle on our fettuccine bridge. From the precedent
we also learn where are the compression and tension being applied on the bridge when
the load is being put on.
2.2 Materials and Equipment Testing
For the second step, we decided to do a test on the compressive and tension strength of
the fettuccine pasta. We bought several different brands of fettuccine pasta and conduct
an analysis. The brands tested were San Remo, Kimball, Giant, and Prego. From the
analysis we concluded that San Remo was the best brand for us to use as it has a thicker
and stronger layer compared to the other brands. The same method was being use for
testing which adhesive suits the San Remo fettuccine to connect the joints and layers.
2.3 Model Making
After decided on the type of fettuccine and adhesive to use, we proceed with the model
making of the fettuccine bridge. For the first few test we tried doing several designs and
arrangement of the trusses and improve our design from the test. After every test, we will
analyse what is wrong with the particular bridge and try to improve the structure to make
it stronger in order to support a lot of weight.
2.4 Bridge Efficiency Testing
The efficiency of the bridge tested is calculated using the formula:
4. Efficiency, E = Maximum Load
--------------------------
Weight of the bridge
CHAPTER 3:
PRECEDENT STUDY
DEARBORN RIVER HIGH BRIDGE
3.1 History
Name of bridge : Dearborn River High Bridge
Year : 1897
Location : Lake Bean Road, Montana, United States
The bridge is a Pratt half deck truss which means the deck is attached midway on
the structure instead on the top or bottom chord like how the usual Pratt truss would look
like. This truss structures is famously used in the late 19th and early 20th centuries .The
bridge is one of the few bridges left in United States with the half deck design with pin
5. connected Pratt. With this design, the bridge managed to carry light loads across the high
and deep crossings. Originally the bridge has four spans and had wooden plank deck.
The river was named by Lewis and Clark, after the United States Secretary of War, Henry
Dearborn in 1805. The Kind Bridge Company of Cleveland, Ohio specifically made the
rare designed bridge for the Dearborn River Canyon. The bridge acts as the railroad for
the farmers and ranchers who lived in that area. It is located above a river ford that was
used for generations by the Blackfeet and other tribes to travel to the Great Plains to hunt
buffalo. In 2003, the bridge was improved by the Montana Department of Transportation
with Sletten Construction of Great Falls, Montana. It lasts as an excellent example of a
rare bridge type and serves as a reminder of the early days of transportation in Montana.
3.2 Structure
Pratt truss
Material Steel, Concrete, Stone
Total Length 251 feet (77m)
Width 16.1 feet (4.9m)
Height 100 feet (30m)
Longest Span 160.1 feet (48.8m)
Pratt truss was invented in 1844 by Thomas and Caleb Pratt. The truss can be
used with spans up to 76 meters and was a commonly used design for railroad bridges
as truss bridges moved from wood to metal. The Pratt truss includes two members which
are vertical and diagonals that slants down towards the centre. The vertical members are
under compression whereas the diagonals members are under tension under balanced
loading. Crossing elements will need to be use near the centre for it to accept
concentrated live loads as it cross across the span, if pure tension elements are used in
the diagonals. The Pratt truss provided a low maintenance, durable and easily
prefabricated bridge that could accommodate the expanding railroad and highway
systems.
6. The bridge has four spans including the 160 foot half deck truss. The plank is
supported by timber stringers and steel I beam where as the main span rests on the
concrete piers protected by steel.
1) Side view of the bridge
2) ‘Barrel Shot’ of the bridge
8. The truss uses pin-connections instead of rivets. This method helps to simplify the
construction process and allowed easy prefabrication of the bridge components. Pin
connections were commonly used for truss bridges until 1909. A pinned support can resist
both vertical and horizontal forces. They will allow the structural member to rotate but not
to translate in any direction
2) Cross bracing
9. In this construction, the cross bracing is used as a system to reinforce the building
structures where the diagonal supports intersect. Using this method, it can help to make
the bridge more rigid to withstand the loads.
3) Zoom in on the pin connection
10. CHAPTER 4:
MATERIALS AND EQUIPMENT
4.1 Materials
4.1.1 Fettuccine
4.1.1.1 Comparison of Different Fettuccini Brands
In order to select the most suitable brand of fettuccine to use for the construction of our
truss bridge, we purchased 4 different brands of fettuccine and carried out test to
determine their tensile and compressive strength. The 4 brands we selected were
Kimball, Giant, Prego and San Remo.
San Remo Prego Fettuccine Kimball Fettuccine
4.1.1.1 Compressive Strength Test for Different Fettuccini Brands
Compressive strength test is conducted by tying 10 sticks of 5cm length fettuccine in a
bundle. The bundle is placed on a weighing scale and force is exerted onto the bundle
until the fettuccine breaks. The maximum load sustained is recorded as shown in the
figure
below.
Brand Maximum load(kg)
Kimball 22
Giant 24
Prego 22.3
Bundle of 10 sticks of
5cm fettuccine
Force is exerted on
the bundle
The testing is ended
when the bundle
breaks
The table above shows the results obtained for the
compressive strength of different brands of fettuccine
11. 4.1.1.2 Tensile Strength Test for
Different Fettuccini Brands
Tensile strength test is conducted by tying a
single stick of 5cm length fettuccine to a luggage scale. The fettuccine is pulled until it
breaks and the maximum load sustained is recorded.
4.1.1.3 Conclusion of Compressive and Tensile Strength Test
The results obtained from both test show that San Remo brand fettuccine has higher
compressive and tensile strength in comparison to the other brands tested. Furthermore,
the test also proves that fettuccine is a material that has better tensile strength than
compression strength.
San
Remo
33.7
Brand Maximum load (kg)
Kimball 300
Giant 350
Prego 310
San
Remo
400
The table above shows the results obtained for the tensile
strength of different brands of fettuccine
A single stick of 5cm
length fettuccine is
tied to a luggage scale
The fettuccine ispulled
until it breaks
12. 4.1.1.4 Compressive and Tensile Strength Test for Different Arrangements of
Fettuccine
Arrangemen
t
Weight (g) Compressive
Strength/
Maximum load (kg)
Tensile Strength/
Maximum load (kg)
One layer
25 20 400
Two layer
25 20 500
Three layer
25 20 600
Four layer
25 20 1200
25 20 1000
13. Using the same method as shown in section 4.1.1.1 and 4.1.1.2 of this report,
compressive and tensile strength test were carried out on different arrangements of
fettuccine.
4.1.1.5 Conclusion of Compressive and Tensile Strength Test
The results obtained from both test show that the four layer arrangement of fettuccine has
the highest compressive and tensile strength. However, the weight of the four layer
arrangement when compared to the I-beam arrangement is lighter while achieving almost
the same strength. Thus, we can conclude that the I-beam arrangement is the best
arrangement to use to minimise weight and achieve high strength.
4.1.2 Adhesive
4.1.2.1 Comparison of Different Adhesives
Type of adhesive Analysis
V-Tech Super Glue
Fastest bonding time (about 3 seconds)
High bonding strength
Clean connection of joints
Disadvantage: most likely to cause fettuccine to
become brittle over a period of time
Elephant Super Glue
Fast bonding time (about 10 seconds)
High bonding strength
Disadvantage: Troublesome to use as joints must be
held in place while waiting for the glue to dry
UHU-Glue
Slow bonding time (about 35 seconds)
Easy to apply
Disadvantage: Takes long to dry and does not give a
firm connection of joints
I-beam
14. Hot Glue Gun
High bonding strength
Joint connections are very firm
Disadvantage: Bulky finish and adds a considerable
amount of weight
4.1.2.2 Conclusion of Adhesive Comparison
After testing the different types of glues we decided to use only the V-Tech Super Glue
for the entire design. The reason we chose the V-Tech Super Glue is because it dries
quickly and allows for a clean connection of joints. However, when using this glue we
must be careful to not leave the bridge to dry for an extended period of time as it causes
the fettuccine to become brittle thus weakening the strength of the bridge.
4.2 Equipment
Type of adhesive Analysis
Craft knife
For cutting fettuccine
Suitable for making clean cuts
Elephant Super Glue
Use to sand the fettuccine
Sanding the fettuccine will allow for better contact and
bonding
Pail
Used to contain water to test the load on the bridge
S-hook
Used to attach the pail to the bridge
15. Electronic balance
Used to weigh the bridge and ensure that it does not
exceed the 70g requirement
Can read up to 2kg of weight
Weighing scale
Used in the compressivestrength test of fettuccine to
measure the maximum load sustained
Luggage scale
Used in the tensile strength test of fettuccine to
measure the maximum load sustained
16. CHAPTER 5
BRIDGE TESTING AND ANALYSIS
SUNDAY, APRIL
10th
- Test the brands of fettuccine to be used, which layers are
stronger, adhesive strength to hold the fettuccine, I- beam and
C- beam
- Test the strength of compressive and tensile on each brand of
fettuccine
SUNDAY, APRIL
16th
- Discussion on which type of truss should be use
- Testing the strength of type of joints to be use
- Do a mock up bridge to understand on how to maintain the
workmanship and how it works
WEDNESDAY,
APRIL 20th
- Discussion on how to design the first bridge
- Construct the first bridge
- Load testing of the first bridge
- Analyze the cause of failure of the first bridge
FRIDAY, APRIL
29th
- Discussion on how to improve the design for the second bridge
- Proceed in constructing the second bridge
- Load testing for the second bridge
- Analyze the problem with the second bridge
SATURDAY,
APRIL 30th
- Discussion on how to improve the design for the third bridge
- Proceed in constructing the third bridge
- Load testing for the third bridge
- Analyze the problem with the third bridge
MONDAY, MAY
2nd
- Discussion on how to improve the design for the fourth bridge
- Proceed in constructing the fourth bridge
- Load testing for the fourth bridge
- Analyze the problem with the fourth bridge
17. SUNDAY, MAY
8th
- Discussion on how to improve the design for the final bridge
- Proceed in constructing the final bridge
MONDAY, MAY
9th
- Final submission for the fettuccine truss bridge
5.1 Bridge Testing and Analysis 1
5.1.1 Designing Pratt Truss with Different Height and Number of Truss
The first step of our analysis was to design bridges with different heights and number of
truss.
Height (cm) Number of Truss
7.0 4
Height (cm) Number of Truss
9.0 4
Height (cm) Number of Truss
9.0 6
18. 5.1.2 Testing with Load
The bridges were constructed based on the designs and tested with load. The results
were recorded for further analysis.
Test Results:
1) 9cm height, 6 truss
Load (g) Observation Carrying Weight (g)
540 g Stable 540 g
797 g Breaks 1337 g
DETAILS OF THE BRIDGE
Height (cm) Number of Truss
7.0 6
Constructed bridges
Weak points: Bottom members break off
19. Height: 9cm
Number of trusses: 6 truss
Clear Span: 350mm
Overall Span: 490mm
Weight: 70g
Max Load: 1337g
Efficiency = 1337g ÷ 70 g = 19.1
Weak Points
The whole bottom member of the bridge breaks (uses 1 layer I-beam and 1 layer of
fettuccine)
ANALYSIS OF PROBLEMS
1) Height and trusses
Based on the precedent studies that we did, we realized that the bridges have
different design in terms of the height and trusses that they used. Due to that, we
try to analyse how the outcome will be if we change the height and number of
trusses in order to achieve a stable bridge that can withstand a lot of load.
For the first design, we tried using the 9cm as the height and used 6 trusses. Based
on our analysis the bridge should be able to distribute the load evenly and
withstand a lot of weight. The distance between trusses was 5.8cm.
2) Poor Workmanship
Since this is our first time doing a scaled model of the fettuccine, it took us
sometime to understand how does connection works, to angle them perfectly into
its position and so on. Due to that reason, the outcome of the first bridge is poorly
constructed and caused failure.
3) Weak Joints
For the first bridge, we had problems in connecting the diagonal members into the
specific angled. Due to not knowing how to properly do it, we just stick the diagonal
members with the vertical members without considering the surface should be
20. connect with each other. The hole in between the joints caused the bridge to have
weak joints.
2) 7cm height, 4 truss
DETAILS OF THE BRIDGE
Height: 7cm
Number of trusses: 4 truss
Clear Span: 350mm
Overall Span: 490mm
Weight: 70 g
Max Load: 2127g
Efficiency = 2127g ÷ 70 g = 30.4
Weak Points
The middle I beam breaks (uses 1 layer I- beam)
The top chord bends (1 layer of fettuccine)
Load (g) Observation Carrying weight (g)
540 g Stable 540 g
797 g Broke from top chord 1337 g
420 g Bending at one side 1757 g
370 g Breaks at the center 2127 g
Weak points: Middle I-beam breaks off
21. ANALYSIS OF PROBLEMS
1) Height and trusses
In this design we decrease the height from 9cm to 7 cm but remained with the
same number of trusses which is 4. By decreasing the height, we were able to
achieve more load and efficiency in the second bridge.
3) Weak Joints
As for this design, the vertical and diagonal members were not glued together
properly, spaces can be seen in between the connection, thus cause the bridge to
bend and breaks at the top chord even before reaching the maximum amount of
load that it can withstand. The top chord layers which is the compression was only
supported with 1 layer of fettuccine which also caused why it bend and broke the
bridge.
4) 9cm height, 4 truss
Load (g) Observation Carrying Weight (g)
460 g Stable 460 g
797 g Stable 1257 g
410 g Bending 1667 g
314 g Bending + Shaking 1981 g
311 g Bending + Shaking +
Swaying
2292 g
290 g Breaks 2582 g
DETAILS OF THE BRIDGE
Height: 9cm
Weak points: Side support and bottom members break off
22. Number of trusses: 4 truss
Clear Span: 350mm
Overall Span: 490mm
Weight: 68g
Max Load: 2582g
Efficiency =2582g ÷ 68g = 37.9
Weak Points
The bottom chord of the bridge broke (uses 2 layers and 1 layer)
The bottom members broke (uses 1 layer I beam, 2 layers and 1 layer)
ANALYSIS OF PROBLEMS
1) Height and trusses
In this design we decided to increase the height again but used less trusses. We
also take into account the proportion of the bridge. Compared to the second bridge
design, this bridge managed to withstand more load and achieve higher efficiency.
2) Problem with material
Due to not carefully going through the fettuccine pasta to find straight fettuccine
piece, we ended up using a slightly slanted fettuccine piece as part of our bottom
chord I-beam, this also contributes to why does the bottom chord of fettuccine
breaks. Due to using less layers for the top chord, it caused the bridge to bend and
sway.
4) 7cm height, 6 truss
Load (g) Observation Carrying Weight (g)
Weak points: Top chords bend and middle I-beam breaks off
23. 540 g Stable 540 g
797 g Sway 1337 g
420 g Stable 1757 g
370 g Stable 2127 g
314 g Bending at one side 2441 g
359 g Breaks 2800 g
DETAILS OF THE BRIDGE
Height: 7cm
Number of trusses: 6 truss
Clear Span: 350mm
Overall Span: 490mm
Weight: 70g
Max Load: 2800g
Efficiency = 2800g ÷ 70g = 40
Weak Points
The top chord of the bridge breaks due to cannot withstand the compressive
strength (only using 1 layer of fettuccine)
The I- beam at the middle part also breaks.
ANALYSIS OF PROBLEMS
1) Height and trusses
Based on the first 3 bridges that we did, we decidedto use shorter height and more
trusses for this design. It may weigh more than the third bridge but it can withstand
more load and higher efficiency.
2) Weak Joints
The joints of the members were also not connected properly. Some of the
members were not glued and in contact with each other which leads to why the
load did not managed to distribute evenly and breaks before reaching the highest
24. load. For the top chord (compression) we still maintained using 1 layer of
fettuccine causing it to bend and breaks as it can’t withstand lot of loads.
3) Poor Workmanship
Our workmanship is still not good enough and caused a problem as to why do the
bridge breaks easily.
5) 5cm height, 8 truss
DETAILS OF THE BRIDGE
Height: 5cm
Number of trusses: 8 truss
Clear Span: 350mm
Overall Span: 490mm
Weight: 73 g
Max Load: 7500 g
Efficiency = 7500 g ÷ 73 g = 102.7
Weak Points
The middle I beam breaks (2layer I-beam used)
Bottom beam breaks at the side
After the failure of the four previous bridges, this bridge was designed of more trusses
and lower height for more stability and efficient distribution of load. The three inside
vertical members where made of 3 layers of fettuccini because force is applied in the
centre compression force would be higher. The other 2 vertical members on both ends of
the bridge where made of 2 layers of fettuccini as these two members will face less force
and to reduce the overall weight of the bridge. However all the diagonal members were
made of 2 layers except the two at both ends are made of 1 layer this is because the
25. fettuccini is naturally stronger in tension strength rather than compression so layers were
reduced to maintain a minimum weight. This bridge stood up to 7.5 kg however the weight
exceeded the requirement.
CHAPTER 6:
26. FINAL BRIDGE TESTING
6.0Final Model
16.1. Amendments
After testing all the bridges, we have decided to use the Pratt truss with 6 triangles
design as our final model because it has the highest efficiency among all the other
truss bridge. Based on the result, in depth analysis was conducted for further
development in order to reach to achieve a higher efficiency and better performance.
6.2. Joint Analysis
Joining method in the bridge is most important factor as it will affect the bridge
performance and its efficiency whether it’s a success or a failure bridge. We did a
study and tested every joint to get the optimum joining of every single member
with different joint and connection. Therefore, the respective joint are designed
accordingly.
Joint A Joint B Joint C Joint D Joint E
27. 6.2.1 Joint A
On the initial joint A, we realized that when the force is applied on the slanted
member, it broke off easily at the edge of the member and the bridge could not
withstand much load. Through observation and analysis, we figured out that
it’s better if we trim it and stick closely to each other. We figured out that the
joint doesn’t have much surface contact with the other member and the loads
can’t transfer completely, therefore causing an efficiency of the bridge low in
whole.
6.2.1 Joint B
This joint is used at the upper part and the lower part in the bridge making.
Based on the observation and analysis we decided to use this joint because it
has more surface contact with the other member and it can’t break easily.
6.2.1 Joint C
28. Initially, we insert the vertical member in between the horizontal member and
joint it vertically. However, when the load is applied on the bridge, the bottom
chord breaks off. In order to improve the efficiency of the bridge, we decided
to placed the I-beam on top of both horizontal member. Thus, improved the
overall performance of the bridge.
6.2.1 Joint D
Initially, we didn’t pay much attention to the detail of the vertical member
because we didn’t know that it’ll affect the overall performance of the bridge.
After through observation, we found out that a ‘slightly’ different height does
affect the overall design performance. So we decided to stick the upper chord
to each of the end of the vertical member and trim the rest of the middle
vertical member with sandpaper. By doing so the member’s surface stick
closely to the other member’s surface, thus, improve the overall load
distribution of the bridge.
29. 6.2.1 Joint E
From our previous design of the bridge we cut the extra upper chord for
aesthetic value but based on the previous observation and analysis, the excess
allows for better connectio between members.
6.3. Final Bridge Testing and Load Analysis
Final Bridge Design
Efficiency of the bridge:
Bridge weight : 67g
Load : 6600g
Efficiency : 67g = 98.5E
6600g
30. CHAPTER 7:
CONCLUSION
By the end of the project, we had constructed a total of 14 Fettuccine Bridge to
achieve the highest efficiency in withstanding loads. In general, we managed to keep the
bridge under the 70g weight limit with a load of more than 3 kg. Our bridge managed to
hold 6.6 kg of load with just 68g weight of the bridge. We realized that is it significant to
study and identify the truss form and joints before constructing a bridge. Furthermore,
workmanship is also important to ensure the members and joints are strong and
connected perfectly to avoid cracking in between them.
Not only that, this project has made us understand more about load distribution in
a structure. We learned to calculate the efficiency and type of force applied in each
structural member realizing the importance to identify the force (tension/ compression/
zero/ critical) in structural members in order to achieve a high efficient bridge. We also
discover that it is important to have a proper way in determine the shape, force in the
members in order to produce an efficient bridge not only in terms of quality and material
but also time usage on producing the bridge.
Forces and load plays an important role in designing a bridge. Hence, there is a
lot consideration that we must take in before constructing a bridge that can sustain certain
load on the bridge. Therefore, it is crucial to clearly understand the load distribution before
a bridge is designed. From this project, we were able to understand the theories behind
the forces distribution of compression and tension forces within a truss system.
In conclusion, it has been a great experience working on this project. This project
teaches us the proper way to construct a truss structure. Using household goods to
construct a bridge and gaining so much knowledge after that have amazed us how strong
a structure can be if it is properly designed and constructed. Moreover, good
workmanship and good team work are also the keys to success in this project.
CHAPTER 8:
34. 1) Dearborn Bridge. (n.d.). Retrieved April 9, 2016, from
http://www.metnet.mt.gov/Special/Quarries From The Gulch/HTM/Dearborn.shtml
2) Dearborn River High Bridge. (n.d.). Retrieved April 1, 2016, from
http://missoulian.com/dearborn-river-high-bridge/article_94178482-cb01-11e3-
b118-0019bb2963f4.html
3) Modeling a Pratt Truss Bridge | COMSOL Blog. (2012). Retrieved April 29, 2016,
from https://www.comsol.com/blogs/modeling-a-pratt-truss-bridge/
4) Bridge Height. (n.d.). Retrieved April 29, 2016, from
http://www.garrettsbridges.com/design/bridge-height/
