1. BUILDING STRUCTURES
[ARC 2213]
FETTUCCINE TRUSS
BRIDGE ANALYSIS
REPORT
CHOO AI LIN
0317253
ELAINE BONG
0310432
LAU EE TIAN
0309596
SOH YOH SHING
0308010
SURAYYN SELVAN
0309818
2. BUILDING STRUCTURES [ ARC 2213 ]
TABLE OF CONTENTS
1 INTRODUCTION
2 METHODLOGY
2.1 PRECEDENT STUDY
2.2 MAKING OF FETTUCCINE BRIDGE
2.3 REQUIREMENT
3 PRECEDENT STUDY
4 ANALYSIS
4.1 STRENGTH OF MATERIAL
4.2 ADHESIVE ANALYSIS
5 MODEL MAKING
5.1 METHOD OF CONSTRUCTION
5.2 JOINT
6 TESTING
6.1 FIRST BRIDGE
6.2 SECOND BRIDGE
6.3 THIRD BRIDGE
6.4 FINAL BRIDGE
7 DESIGN MODIFICATION
7.1 FAILURE REASONING
7.2 SOLUTION
8 CONCLUSION
9 APPENDIX
10 REFERENCES
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3. BUILDING STRUCTURES [ ARC 2213 ]
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1 INTRODUCTION
This project aims to develop our understanding of tensile and compressive strength of construction materials by understanding the distribution of force in a truss.
In order to do achieve that, we were required carry out a precedent study on a truss bridge of our choice, analyzing the connections, arrangements and orientations of the members. Once that was completed, we were required to design and construct a truss bridge made out of fettuccine.
The requirements for this bridge include it having a 750mm clear span and a maximum weight of 200g. This bridge will then be tested to fail and we were required to analyze the reasons of its failure and calculate its efficiency.
4. BUILDING STRUCTURES [ ARC 2213 ]
2 METHODOLOGY
2.1 PRECEDENT STUDY
By looking through precedent studies to have a better understanding of the types of trusses available. Next, understanding the forces that would be exerted to the trusses; compression and tension, would allow us to make adjustment to our bridge, that would best suit the given material; fettuccine.
2.2 MAKING OF FETTUCCINE BRIDGE
PHASE 01: STRENGTH OF MATERIAL
Understanding the properties of the fettuccine is important in order to build one bridge that can carry maximum load. For the tensile strength in the fettuccine is considerable low when compare to aluminium which has the same amount of stiffness to the fettuccine.
PHASE 02 : ADHESIVE
Choosing the right type of adhesive is important as it plays a huge role in this assignment. As there are many types of adhesive in the market that each has their own function and characteristics. Not only the type of adhesive is important but the brand of adhesive is important as well, for different brand has different quality and choosing one that suits constructing the fettuccine bridge is primary.
PHASE 03: MODEL MAKING
To ensure precision in our model making, Autocad drawings are drawn in 1:1 scale and plotted out to ensure precision and ease our process. And in order to strengthen our bridge as much as possible, each pasta is marked individually as each has their own location of placement and length, and are glued accordance.
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5. BUILDING STRUCTURES [ ARC 2213 ]
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2 METHODOLOGY
PHASE 04 : MODEL TESTING Finished models are being tested after placing aside to allow the adhesive to sit on the model. By placing weight on the middle of intermediate member to ensure that load is evenly distributed. All these are being recorded to allow us to fix and analysis our bridge. 2.3 REQUIREMENTS
•To have a clear span of 750mm
•Not exceeding the weight of 200g
•Only material allowed is fettuccine pasta and adhesive
•Allowed to use any type of adhesive possible
•Workmanship is put to consideration as part of aesthetic value
6. BUILDING STRUCTURES [ ARC 2213 ]
3 PRECEDENT STUDY
The Heshbon Bridge, located at Indiana, Pennsylvania state in the United State of America, is one of the last state-standard truss bridges built. Many bridge were constructed across the Pennsylvania state from the late 1920's through 1941. This bridge was constructed in 1941 by Paul Construction Company and Pennsylvania State Highway Department which has a main span of 153ft(46.6m) with a total length of 158 ft(48.2m) and 26ft(7.9m) roadway width over the Black Lick Creek.
HESHBON BRIDGE, INDIANA (1941)
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7. 3 PRECEDENT STUDY
This bridge is a relatively small example of Pennsylvania's very attractive standard plan of 1930s to 1940s truss bridge design. As such, it features a shallower portal bracing design that other bridges built to this standard. In 2009, the government wanted to replaced the bridge but fortunately they decided to rehabilitate it instead of replacing it. This will include a deck replacement as well as structural steel repairs. So, the Heshbon bridge represents a good preservation project and it became one of the tourist attraction in Pennsylvania.
BUILDING STRUCTURES [ ARC 2213 ]
Heshbon Bridge from 1941-2009
Old railroad bridge with wooden pathway.
Heshbon Bridge 2009 until today
After rehabilitate, the bridge became a bike path
Heshbon Bridge Before Restore
Heshbon Bridge After Restore
The map above shows the bridge is located over Black Lick Creek In Heshbon, Indiana County, Pennsylvania.
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8. 3 PRECEDENT STUDY
BUILDING STRUCTURES [ ARC 2213 ]
The 1941, skewed, 158ft long, riveted Parker truss bridge is supported on ashlar abutments with concrete caps. The trusses are traditionally composed with the upper and lower chords being built up box sections, and the verticals and diagonals rolled I sections. Lateral and sway bracing are laced channels. The deck is reinforced concrete, and the steel railings inside the truss lines are original.
TRUSS CONNECTIONS AND MEMBERS
Portal view on bridge
Top chord connections
Bottom chord connections.
Connections of truss web
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9. 3 PRECEDENT STUDY
Vertical member detail
End Post
BUILDING STRUCTURES [ ARC 2213 ]
Railing detail
Railing
Abutments
Ashlar abutment
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10. BUILDING STRUCTURES [ ARC 2213 ]
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4 ANALYSIS
4.1 STRENGTH OF MATERIAL
WEIGHT
With the requirement of only 200G, we had to creative solution, to reinforce our bridge while making sure that the weight of bridge does not exceed the requirement. Thus we came our with solution by selecting parts that holds load and reinforce it by adding layers to it. But bearing in mind that the more layers added, the more weight it holds.
Before we started our model making, we did a little experiment of the maximum weight the fettuccine can carry. We tried out with 4 different layers to carry out this experiment.
Experiment (left to right):
I.One Layer
II.Two Layers
III.Three Layers
IV.Four Layers
Experiment 03: Three Layers
When load is applied, members could be seen slightly sturdier when compare to Experiment 2. But a slight bend in the middle could be seen. Total weight being 2.8G
Experiment 02: Two Layers
In the two layer of fettuccine, a slight bend could be seen in the fettuccine, although it is not as extreme as Experiment 1. Total weight being 1.17G
Experiment 01: One Layer Members starts to bend after load is applied with just one layer of fettuccine. Total weight being 0.56G.
Experiment 4: Four Layers
With four layers, it has proven to be the most stable option among all experiments. Total weight being 2.05G.
Properties of spaghetti (dry) 1. Ultimate tensile strength ~2000 psi
2.Stiffness (Young’s modulus) E ~10,000,000 psi (E=stress/strain)
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4 ANALYSIS
4.1 STRENGTH OF MATERIAL
ORIENTATION
Horizontal members were placed between trusses, to hold both pieces of the bridge together. They held no force besides balancing the whole truss bridge. Hence, we reduced the horizontal members to one layer in our second and third bridge, for our bridge to fit the requirement in terms of the bridge’s weight.
VS
Method 01 was used in our case because the members were fitted between the arch and the bottom chord. This can ensure that the load was distributed evenly to the arch. Comparing to Method 02, which the bracings were glued on the outside truss. Thus, Method 01 was a better choice of orientation. Where Method 02 is still able to distribute the load but the bracings were not secured onto arch and bottom chord, relying on the glue
Method 01
Method 02
The intermediate member is where the hook that held on load is placed. Making its role important. Where the orientation and its layers are vital. We found out the load can be transferred more efficiently when it was placed exactly in the middle in upright position, where the load can be distributed evenly to the sides.
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12. BUILDING STRUCTURES [ ARC 2213 ]
4 ANALYSIS
4.2 ADHESIVE ANALYSIS
Type of Adhesive
Advantages
Disadvantages
X’traseal’s Super Glue
•High efficiency
•Fast solidify time
•Easy to use
•Easy to bend fettuccine when applied
•Cracked joint after dried for few days
Selleys’ Supa Glue
•High efficiency
•Fastest solidify time
•Easy to use
•Cracked joint after dried for few days
UHU Glue
•Easy to use
•Low efficiency
•Causes flexible joints
•Longer solidify time
•Causes bridge to weigh more
Three different kinds of glue used to ensure the joints are strong and thus strengthen the bridge.
Selleys’ Supa Glue was used the most while constructing our fettuccine bridge. It has high efficiency and it dried faster compared to the other adhesives, as it is more concentrated when compare to X’traseal’s Super Glue. To make sure the glue worked at its best, allow the glue to settle in the bridge to make sure it is dry before the testing it. This is to ensure the bridge perform at its best.
The X’traseal super glue is only used on the arch where slower solidify of glue is needed in order to buy some time while constructing the arch, for better precision.
UHU Glue is avoided if possible, as it causes the joints to be flexible. It also requires longer time to dry. Making it the worst option, for joints should be rigid.
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13. BUILDING STRUCTURES [ ARC 2213 ]
5 MODEL MAKING
5.1METHODOFCONSTRUCTION
02. We started off by doing the bottom chord of the bridge by dividing the base of the bridge into 4 layers with different length.
03. Then we glued the it together using the method above to distribute the breaking point of the base evenly.
04. For the arc of the bridge, we also divided it into 4 layers. In order the get the shape of the arc, gluing it layer by layer and bend it accordingly.
01. First, we printed out a copy of the design of our bridge so that it will be easier for us to bend the fettuccine to get the shape of the arc.
05. We cut and glued the vertical truss and the bracing of the bridge. After completing one side of bridge, we used the same method for the other side
06. Finally, we connected the 2 sides of the bridge by placing horizontal fettuccine in between.
Joint
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5 MODEL MAKING
7. The middle piece of the horizontal truss is reinforced as it was the piece that holds the weight.
9. The completed final model.
8. The top parts of the bridge are joined with double layers of fattucine.
5.1METHODOFCONSTRUCTION
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5 MODEL MAKING
5.2 JOINT
PLAIN BUTT JOINT
1. Two fettuccine doubled-layer to make it stronger
3: Repeat this procedure.
2. Join one fettuccine to other the end of another fettuccine.
Final Product
OVERLAID JOINT
1. Randomly choose 2 fettuccine.
2. Place a fettuccine horizontally in between of the 2 fettucine.
3. Trim the excess and repeat the procedure.
Final Product
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6 TESTING
6.1 FIRST BRIDGE
For our first bridge we used the precedent study as a guideline for our first bridge. By changing it to an arch to allow the bridge to increase the compression member. On our first trial we did not focus much on the weight of our bridge but more our reinforcing it and
understanding the adhesive and the orientation of the trusses. Although our required clear span is just 750MM we added an additional 74MM on each sides of our bridge to allow it to rest on the table, in order to spread the load applied on bridge. Each segments having a total length of 80MM allowing us to produce total of an odd 11segments where we produce just one ‘X’ truss on the middle segments. This is part of our technique in order to produce as little weight than producing an even number of segments where we would be force to produce two ‘X’ truss in order to be centralized.
Model Testing
Middle of intermediate member broke off after 6KG
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6 TESTING
6.1 FIRST BRIDGE
Length:
Width:
Height:
Weight:
Max. Load
Efficiency
After a few trials, only the intermediate member would broke after applying force. Proving that our truss is stable. Thus, the only problem with our bridge is the weight of it. Resulting in the second bridge.
LOAD
Compression
Tension
209MM
908MM
90MM
FAILURE
Two layers
Four layers
908MM
90MM
209MM
225G
6KG
0.16
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18. BUILDING STRUCTURES [ ARC 2213 ]
6 TESTING
6.2 SECOND BRIDGE
The second bridge also followed the design of the precedent study - Heshbon Bridge similar to the first bridge. The first bridge was too heavy as we have a weight limit stated by the brief which was 200g. We decided to maintain the height and the bottom chord
chord because these two were the most important members in a truss. So we reduced the layers of the zero force members which were the horizontal members holding both truss together. Two intermediate members were place in the middle where the load would be hung. One, which had four layers, was placed in the centre of the whole truss to hold the both trusses together. The other, which had eight layers, was placed diagonally on the bottom chord intersecting with the middle member.
Intermediate member bending just before it breaks.
Broken intermediate members
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19. 209MM
900MM
90MM
LOAD
Compression
Tension
FAILURE
Two layers
Four layers
One layer
BUILDING STRUCTURES [ ARC 2213 ]
6 TESTING
6.2 SECOND BRIDGE
Length:
Height:
Width:
Weight:
Max. Load:
Efficiency:
Only the intermediate members of the second bridge broke off without damaging the truss which means that it had not achieved its maximum efficiency yet with the load of 5KG.
908MM
90MM
209MM
225G
5KG
0.12
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20. BUILDING STRUCTURES [ ARC 2213 ]
6 TESTING
6.3 THIRD BRIDGE
besides increasing stability, we also reduced 0.7G of weight which contributes into higher efficiency. Total height of the third bridge is 178MM. Proven that our proposal of reducing the height was a success. Conversely, when the height decreased, the center of gravity become lower hence the bridge become more stable., standing up straight raises the center of gravity above the base of support and decreases stability. The amount of layer used in each location of the member is the same because we couldn’t afford to lessen the layers of the bottom chord or the arch, thus we choose to shorten the height instead.
After considering from failure of the second bridge design, we intended to reduce the height of the arch
Perspective view of third bridge. Placement of horizontal member is the same with previous bridge
Model testing.
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21. Two layers
Four layers
One layer
BUILDING STRUCTURES [ ARC 2213 ]
6 TESTING
6.3 THIRD BRIDGE
LOAD
Compression
Tension
178MM
908MM
90MM
FAILURE
The reason third bridge failed is because the horizontal member was just one layer causing the joint not to be strong enough to withstand the load exerted onto the bridge. And the intermediate member broke fall off, issuing a problem with workmanship.
908MM 90MM 178MM 200G 3.8KG 0.0.722
FAILURE
Length
Width
Height
Weight
Max. Load:
Efficiency:
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22. BUILDING STRUCTURES [ ARC 2213 ]
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6 TESTING
6.4 FINAL BRIDGE
were broken. We decided to rearrange our horizontal bracing. Instead of using one strip of fettuccine we decided to have two layers but reduce the number of horizontal bracing, thus we managed not to exceed much weight as stated in requirement. We mainly placed these bracings where the forces would act most upon.
By rearranging and adding the additional layer of to the horizontal fettuccine members, it managed to increased the efficiency of our bridge. During the final testing of our bridge, the middle of the immediate member of our bridge broke under the force exerted by the load.
After the testing of our third bridge, our arch and trusses were still in tact and only the horizontal braces connecting the trusses
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6 TESTING
6.4 FINAL BRIDGE
LOAD
Compression
Tension
178MM
908MM
90MM
FAILURE
Two layers
Four layers
One layer
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7 DESIGN MODIFICATION
7.1 FAILURE REASONING
Reason 01:
The bottom chord of our bridges aren’t completely touching the base at both sides, as it is only partially touching the base. This is due to the lack of precision in our workmanship. This cause our bridge to be unbalance and not stable. Our models could have slipped off when load is being exerted towards bridge. Causing our bridge to be twisted.
Reason 02:
As some of the is slanted and not 180˚ flat, for nothing is perfect. As it is crucial to use a flat fettuccine pasta for when layering the width of layered fettuccine would be uneven at slanted area. And with the slanted part the load distribution would be disturb and unstable
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7 DESIGN MODIFICATION
7.2 SOLUTION
Solution 01: Using masking tape on the members onto the printed drawing, to ensure that members does not slipped off. Thus member would remain constant and provide precision. But one would need to make take into consideration that masking tape is not as strong as we want them to, so members would shift when working on other members. Solution 02: Using UHU Glue to fill the gaps in between joints would help Reason 01, but bearing in mind that weight of bridge would increase and aesthetic value of the bridge would fall. By reinforcing both Super Glue and UHU Glue, structure seems to work just fine with it.
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8 CONCLUSION
From this assignment we were able to have a better grasp of understanding the load and compressive strength of construction material. Teaching us methods as to constructing a building structurally stable. As forces and loads plays an important role in this assignment, aiding us to understand how it is distributed in truss. Not forgetting that we were to be creative and maintain high level of aesthetic value while putting the minimizing the amount of materials used. Hence promoting sustainable architecture.
Group photo along with final bridge
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9 APPENDIX
As for our individual part, we were assigned to further analyse total of 5 trusses. Each were distributed to following : First Case: Second Case: Third Case: Fourth Case: Fifth Case: The analysis and calculations of trusses are attached after this page.
Elaine Bong Poh Hui
Lau Ee Tian
Surayyn Selvan
Choo Ai Lin
Soh You Shing
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10 REFERENCES
Historic Bridges.org.(2012,January 11)..Retrived September 20,2014,from http://www.historicbridges.org/info/about.htm