ARC 2523: BUILDING STRUCTURES Project 1: Fettuccine Truss Bridge
WONG TENG CHUN LING YUAN MING LIM CHOON WAH ALEXANDER CHUNG SIANG YEE HIEW EYANG EVELYN SINUGROHO
0318538 0318758 0311265 1003A78541 0317737 0318217
1.0 Introduction 1.1 Introduction of Project 1.2 Aim and Objectives 1.3 Scope and Limitations 1.4 Methodology 1.4.1 Precedent Studies 1.4.2 Materials Testing and Equipment Preparation 1.4.3 Model Making and Design Development 1.4.4 Structural Analysis 1.4.5 Bridge’s Efficiency Calculation 1.5 Equipment and Materials Need 1.5.1 Strength of Material 1.5.2 Testing of Fettuccine 1.5.3 Experiments of Fettuccine 1.5.4 Adhesive Analysis 1.5.5 Schedule of Work 2.0 Precedent Study 3.0 Experimentation and Progress 3.1 Bridge#1 3.2 Bridge#2 3.3 Bridge#3 3.4 Bridge#4 3.5 Bridge#5 4.0 Final Bridge Design 4.1 Design of Truss 4.2 Members of Bridge 4.3 Connections of the Bridge 4.4 Final Bridge Testing and Analysis Reference Case Studies
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1.0 INTRODUCTION 1.1 Introduction of Project The ‘Fettuccine Truss Bridge’ is the first project in Building Structures (ARC2523). In this project, we were needed to build a bridge using fettuccine as the only material for the bridge truss members. In a group of 6, we were required to carry out a precedent study understanding tensile and compressive strength before constructing the bridge. The requirement of this bridge is to not exceed the maximum weight of 80grams while having a clear span of 350mm. The bridge will then be tested to failure to obtain results and data for further analysis regarding the failure and the efficiency calculation.
1.2 Aim and Objective The aim of this project was to develop an understanding of tension and compression strength of construction materials by first understanding the distribution of forces in a truss. To achieve that, we were to conduct a precedent study on truss bridge to analyze the connections, arrangement and orientations of the members, individually. Thus, by comparing the results, we were able to learn and know how different arrangements can lead to the perfect truss and achieve best performance. Then we were required to design and construct a truss bridge out of fettuccini from the obtained results. By testing the Fettuccini Bridge to failure, students were able to analyze and calculate the efficiency of fettuccine as a material in terms of tension and compression strength. As a result, we developed deeper understanding of tension and compressive strength as well as the distribution of forces in a truss. Hence, the objective was accomplished.
1.3 Scope and Limitations The scope of this project was to construct a bridge fettuccine as the only construction material using only one type of adhesive. The bridge constructed was to have a clear span of 350mm with weight not more than 80g. With the weight limited, bridge designs were also limited. Layering and the number of trusses were given much attention for maximum efficiency and project requirement. Another limitation was the fettuccine production as the strands were not all equally perfect. Almost half of every pack of fettuccine had strands that were twisted and cannot be used for bridge making. Even slight twist of the strands will affect the performance of the bridge.
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1.4 Methodology 1.4.1 Precedent Studies We have conducted a research for truss bridge and study on its connections, arrangement of members and orientation of each members. From the ‘Truss Analysis’ exercise, each student was to choose a case study respectively and needed to conduct analysis and calculation of compression and tensile forces of each truss. In a group, the most effective and efficient truss for the load system was determined.
1.4.2 Materials testing and Equipment Preparation Phase 1: Strength of materials
Phase 2: Adhesive
Phase 3: Model making
Phase 4: Data collection
The understanding of the materials used is very important in order to build a bridge of maximum efficiency. Several brands of fettuccini were tested by simply pressing and pulling the strand of fettuccini. We found out that fettuccini has great tensile strength but weak compressive strength. The type of adhesive will greatly impact the final efficiency of the bridge. There are many types of adhesive but not all are suitable due to different characteristics. Different brands will also produce different end result. Drawings are drawn to scale on paper and model making is based on the drawing. Much caution was put into slicing the fettuccini into desired length as they are brittle and may crack easily. Joints are joined using the glue. All layering and joints are carefully stick together with minimal to no gap and must be perfectly aligned. Completed models were tested by placing weight on the middle of the intermediate member to ensure the load is evenly distributed. Every steps are carefully recorded for data collection and further analysis.
1.4.3 Model Making & Design Development The designs of the bridges were done manually to scale and hand drawn on paper. The bridge model is then made following the drawing.
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1.4.4 Structural Analysis Structural analysis is a determination of the effect of load on the Fettuccini bridge and its member by calculation as done in the ‘Truss Analysis’ exercise.
1.4.5 Bridge’s Efficiency Calculation Efficiency of the bridge is calculated after it was tested to failure by using the formula Efficiency, E =
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1.5 Equipment and Materials Needs SAN REMO FETTUCCINE
The first requirement of model making. SAN REMO is a common brand which can easily found in market.
PEN KNIFE
Pen knife is to cut fettuccine into piece for bridge making process. Each individual in group have different pen knife respectively. However, the function remain the same. Adhesive to all members for the bridge.
V-TECH SUPERGLUE CUTTING MAP RULER
Used to protect the table while cutting the fettuccine. Each member have their own cutting map but the function remain the same. We used ruler to measure the length and marking on fettuccine before cutting it
500ML EMPTY WATER BOTTLE
Used as load during load testing of fettuccine bridge. (2bottles=1kg)
S-HOOK
Used to hook on one point if the bridge.
WATER BUCKET
Bucket as the load and water will be pour inside during load testing.
NEEDLE
To use with S-hook and hook as two point load for the bridge
ELECTRINIC BALANCE
To measure the bridge trust and the load apply of the bridge.
IPHONE
Make recording of bridge testing in slow motion and photograph the procedure of model making.
LAPTOP
Researching purpose for precedent studies, analysis report and reference materials.
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1.5.1 Strength of Materials FETTUCCINE Because fettuccine is only the material to be approved for this project. Thus, various experiments were carried out to test the strengths with different arrangement of fettuccine before constructing any bridges. Because the maximum weight of the bridge required was 80g, not only was the combined strength taken into consideration, but also its weight. Properties of fettuccine: 1. Width 2. Thickness 3. Length (normal unbroken)  
: 4mm : 1mm : 26mm
Ultimate tensile strength =2000 psi Stiffness (Young's modulus) E =10,000,000 psi
Type of Fettuccine
Strength
Average Kimball
Strong San Remo 1.5.2 Testing of fettuccine Before testing the fettuccine, we make sure the way of fettuccine glued in a proper way to prevent and uneven surface bridge.
Figure 3.2.1 Wrong gluing technique
Figure 3.2.2 Correct gluing technique
Figure 3.2.3 Correct gluing technique
Figure 3.2.4 Correct gluing technique
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1.5.3 Experiments of fettuccine The fettuccine beams using staggered arrangement to low down the breaking while minimize the weak spot of the bridge.
Figure 3.3.1 Staggered arrangement of 4 layers of fettuccine
To get the best efficiency of total load can carry by fettuccine beam, we tested several ways of arrangements and orientations to ensure it have the best implement of our bridge LOAD
LOAD
Figure 3.3.2 Horizontal Facing
LAYER(S) LENGTH OF OF FETTUCCINE MEMBERS /mm
Figure 3.3.3 Vertical Facing
CLEAR SPAN /mm
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26
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LOAD SUSTAINED (HORIZONTAL FACING)/g 430
LOAD SUSTAINED (VERTICAL FACING)/g 200
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26
15
510
320
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26
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770
660
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1300
1000
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1.5.4 Adhesive Analysis Type of adhesive
Advantage Bond Efficiency - Weak Strength efficiency - Average Applying - Easy Duration to dry - Slow
Rank
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UHU GLUE
Bond Efficiency - Medium Strength efficiency - High Applying - Easy Duration to dry - Medium
Bond Efficiency - Strong Strength efficiency - High Applying - Easy Duration to dry - Fast
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E6000 INDUSTRIAL GLUE
V-TECH SUPERGLUE
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1.5.5 Schedule of Work Date 10th September 2015
14th September 2015 15th September 2015
18th September 2015 19th September 2015 21th September 2015 24th September 2015
26th
September 2015
27th September 2015
28th September 2015
Work Progress Research of primary sketches, discuss possible idea of bridge, list of precedent studies Decide material to use Material bought. Discuss general information and details of precedent studies. Testing tensile and compressive strength of fettuccine with different brand, arrangement, orientation as well as the connection by using different glue. Deciding the design of bridge(s) to be build. Build of Bridge #1 and Bridge #2
Testing of Bridge #1 and Bridge #2 Discuss about where to strengthen of the bridge Build of Bridge #3 and Bridge #4
Testing of Bridge #3 and Bridge #4 Discuss about where to strengthen of the bridge and possible change of glue in use Build of Bridge #5 and Bridge #6 Testing of Bridge #5 and Bridge #6 Discuss about where to strengthen of faulty and notation of craftsmanship Build of Bridge #7 Testing of Bridge #7 Notation of craftsmanship and finalize the design of final bridge Build of #final bridge Submission and testing of #final bridge for assessment
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2.0 Precedent Study REIDSTEEL HIGHWAY BRIDGES STANDARD STEEL THROUGH TRUSS BRIDGE
The effective span or clear span of the bridge for construction is between 15m – 240m; this is construction and design standard of REID steel for Truss Archspan Bridge. The compositions are made up of 2-lane Carriageways and 7.3m gaps in between crash barriers. Local reinforced concrete decks of 0.25m thick are added to each bridge. They are placed on the lost formwork decking with no pillar needed. They can have 0.05 of surfacing. It consists of three levels of steel crash barrier on both ends of the carriageways. This design ensure neither trucks nor their payloads can damage the steel trusses. 2 trusses at, and above, deck level carry the bridge decks. Bracing system is added to the two trusses to be stabilized. The bracing system is common as for Raker members down to the transoms, which is below 40 m span. The bridge decks are cambered from side to side using pre-cambered steel transoms; and slightly cambered from end to end by implement built in camber of the trusses. The pedestrian, handcart and cycle traffic are able to cross the bridge through walkways on both side of the bridge. They are out of the main trusses with 1.2 m wide; it also has handrails outside. Hence, the users are protected from the vehicle traffic by the crash trail and main trusses. The specification of the decks is 0.125 thick local reinforced concrete placed on the lost formwork decking.
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The bridge steel is joint together using bolt with regular high strength tension and shear bolts. There are no friction grip bolts. Most of the main connections are end-plated. Adjustment is by means of steel packs, which can be inserted between end plates.
The bridge steel is made in fragment so that it can be transported in 20ft or 40ft containers, or on regular road vehicles. REIDSteel Company design the bridge accord to British Standard BS 5400 for 2 lanes of full highway loading, and for 30 units of HB loading, equivalent to an occasional 120 tons truck. All the structural designs are done in house by REIDSTEEL. For a long life cycle duration with low maintenance, all the steel work is hot dip galvanized 85 microns, 610gm/m2. Construction of the bridge can take place in-situ on a temporary causeway or on temporary jack-able pillar; or maybe be built on the ‘home bank’ and Cantilever Launched across the gap. For the cantilever launch, a ‘Launch Kit’ is needed, consisting of sets of rollers, a steel ‘launching nose’ fitted to the leading edge of the bridge (and removed fro re-use after launch), and come-along cable jacks. The bridges will sit on the elastomeric bearings on the abutments. Expansion joints for the roadway are provided at both ends. Multi-span crossings can be achieved by combining with other bridges. For a multi-span bridge that are to be cantilever launched, it is necessary to apply a ‘Link Kit’ which consists of further 11
sets of rollers, and further jacks, and a set of link steelwork which joins adjacent bridges during the launch and roll-out. As with the Launch Kits, the Link Kits are reusable.
Steel through truss bridge is the most economic bridge for spans 15m to 240m. The carriageway is only about 1.2m above the abutment. A cantilever launch is relatively simple as long as there is a run up equal to 110% of the span is available on the ‘home’ bank. The bridge can easily by built on a causeway in-situ during a dry season. The bridge is good for multiple spans. But a through truss archspan bridge cannot be extended widthways, except by building another parallel bridge.
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3.0 Experimentation and Progress Experimenting on different trusses and altering them to become stronger each time
3.1 Bridge # 1 As for the first design, we have deduced that the equal distribution force would be the ideal design for this assignment. Based on the research, we found that the engineers universally favored the through truss bridge. We started with Waddell ‘A’ truss design and then modified the structure of the bridge to become the bridge in figure 3.1.1. E6000 and 3 second glue was used to be adhesive material for the bridge. E6000 was used for the purpose of joining members and for join connection. Then, 3-second glue is used to enhance the strength to certain part of the model if necessary.
Figure 3.1.1
Figure 3.1.2 Load distribution diagram Clear Span: 230 mm Total Length: 350 mm Height of the Bridge: 80 mm Weight of the Bridge: 78 g Total Load withstands: 2750 g Efficiency: 96.95%
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Figure 3.1.3 Before testing
Figure 3.1.4 During testing
Figures 3.1.5 Breaking
Figure 3.1.6.After testing Test results: As this point load test was our 1st trial, we are able to collect the require data. The highlighted parts on the bridge are the members that fail during the test. Based on the result, we are able to come out with assumption that the upper chords are under compression while the 14
vertical members are under tension. The calculation in the later part of the report shows most of the truss member are compression member compare to the ones under tension. In calculation, the forces are greatly distributed onto the top chord. Consequently, the members fail toward the center.
3.2 Bridge # 2
As for the second design, we have deduced that the equal distribution force would be the ideal design for this assignment. Based on the research, we found that the engineers universally favored the through truss bridge. We started with Howe and Pratt truss design. Then, we’ve modified the structure of the bridge to become the bridge in figure 3.1.1. Where we find this refine version is the optimized version. Compare with the first model, we’ve change the design of the member, bottom chord. To ensure it can withstand greater force, we’ve implement the I-beam concept into the design.
Figure 3.1.
Figure 3.2.3 Load distribution diagram
Clear Span: 250 mm Total Length: 350 mm Height of the Bridge: 80 mm
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Weight of the Bridge: 74 g Total Load withstands: 3500 g Efficiency: 165.54%
Figure 3.2.3 Before testing
Figure 3.2.4 During testing
Figures 3.2.5 Breaking
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Figure 3.2.6.After testing Test results: For this design, we’ve successfully improved the weight capacity. In term of the implementation of I-beam, it wasn’t that effective yet there’s a sign of improvement base on the reading on efficiency. This discovery convinces us to apply on the following designs. On the other hand, we found out that the members that carry the load wasn’t durable against compression. This is because the member carry load was break even before the highlighted part on figure 3.2.3 fail. Hence, we’ve decided to add extra member as reinforcement.
3.3 Bridge # 3
At this stage, we’ve got the required data based on the first and second experiment. Also, we’ve come to an agreement to change the material of the normal San Remo fettuccine to Spanish San Remo fettuccine. This decision was made based on the difference in density. Spanish fettuccine contain higher density. In our assumption, it helps with the internal force. Whence, the design of the bridge remained the same except the member that are intended to carry load. We’ve added extra I-beam member to stiffen the structure.
Figure 3.3.1
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Figure 3.3.2 Load distribution diagram
Clear Span: 250 mm Total Length: 350 mm Height of the Bridge: 80 mm Weight of the Bridge: 80 g Total Load withstands: 7500 g Efficiency: 703.13%
Figure 3.3.3 Before testing
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Figure 3.3.4 During testing
Figures 3.3.5 Breaking
Figure 3.3.6. After testing Test results: Based on the result, it shows our hypothesis was correct as the load capacity increase greatly. We have come to the conclusion that the properties of the material do affect the internal force capacity of the truss. On the other hand, we also come to a conclusion that the main factor of the drastic improvement lie on the extra member to carry load.
3.4 Bridge # 4
At the fourth stage, we needed to fulfill the brief requirement by increase its total length to 450mm to allow clear span of 350mm, yet the design of the bridge preserved. The dimension and cross-sectional design of the member are identical to the 3rd bridge.
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Figure 3.4.1
Figure 3.4.2 Load distribution diagram Clear Span: 350mm Total Length: 450mm Height of the Bridge: 80mm Weight of the Bridge: 90g Total Load withstands: 4000g Efficiency: 177.78%
Figure 3.5.3 Before testing
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Figure 3.4.4 During testing
Figures 3.4.5 Breaking
Figure 3.4.4. After testing. Test results: After we decided to increase the length of the forth bridge, it was reduced to the total load that withstands 4000g to 7500g; and the weight of the bridge was increased from 80g to 90g. The middle part of the design is weakened due to the long span. It should be strengthen more in the bottom cord member. In conclusion, we decided to reduce the span from 450mm to 400mm to increase its strength to carry the point load.
3.5 Bridge #5
For the fifth bridge, it design had become shorter span would able to carry more load compare to fourth bridge by reducing 50mm. The all member type and arrangement are still remaining. 21
Figure 3.3.1
Figure 3.5.2 Load distribution diagram Clear Span: 350mm Total Length: 400mm Height of the Bridge: 70mm Weight of the Bridge: 80g Total Load withstands: 2000g Efficiency: 50 %
Figure 3.5.3 Before testing
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Figure 3.5.4 During testing
Figures 3.5.5 Breaking
Figure 3.5.4 After testing Test results: Overall, the total load withstand by the fifth bridge was 2000g, which was the lowest load. The efficiency calculation had drop down to 50%. We realized that even we shorten the span; we also needed to increase the thickness of the bottom cord member so it could actually affect much of the final load withstand even more. The compression members are more than tensile members which also the reason had been weaken the whole truss system because the Spanish fettuccine was good in tensile strength instead of compression. So we should choose the final design bridge which good in tensile to allow carry more point load among others.
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4.0 Final Bridge Design 4.1 Design of Truss
Figure 4.1.1 3D model of the final Bridge
For our final bridge, we decided to use the Wadell ‘A’ Truss but with slight change of measurements from the trial bridge due to the misunderstood of clear span as the total span. Hence, we assume that the efficiency calculation was going to be similar with the bridge #1 and bridge #3. Although bridge #1 and bridge #3 efficiency were quite low compared to bridge #2 and bridge #4, we decided to use the same type as bridge #1 and #3 as it is aesthetically more appealing and lighter compare to bridge type #2 and #4. Furthermore, as we extend the length of bridge #2 and #4, the carrying capacity decreases while the weight of the bridge increases. When we took away some of the member, the carrying capacity decreases to almost half of the old one. The thickest members of the bridge are the base which were constructed by 4 layers in vertical order and 1 layer in horizontal order glued together. The main diagonal member were constructed by 4 layers of fettuccini members each. According to our findings and analysis, the tensile and compressive strength could be increased by increasing the thickness of the main frame members of the bridge. The supporting members are the vertical and diagonal members inside the frame. They act as the support in transferring the force from the main members. The more the diagonal members, the better the tensile strength of the bridge, which works best with the characteristic of fettuccine as it works best under tension because its flexibility to bend. The addition of vertical members improves the compressive strength of the bridge. The supporting members consists of 2 layers
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each. The connecting members that directly holds the s-hook consists of 2 members with 5 layers each, this is due to the members directly supporting the load.
Figure 4.1.2 Final model of the bridge
Figure 4.1.3 Side view of the bridge model
Figure 4.1.4 Measurement of Final Bridge
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4.2 Members of the Bridge
Figure 4.2.1 Main Frame of the Bridge
Figure 4.2.2 Compressive Vertical Truss Members of the Bridge
Figure 4.2.3 Tensile Diagonal Truss Members of the Bridge
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Figure 4.2.4 Horizontal Bracing as the Connector of Main Frames
Figure 4.2.5 Center Piece of the Bridge Which Directly Holds the S-Hook
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4.3 Connections of the Bridge
Figure 4.3.1 Fettuccine Members of Final Bridge
Figure 4.3.1 shows the different layers of fettuccine according to the members’ function and type to the bridge. The more important the function of the member, the thicker the layer of fettuccine. The purple colored fettuccine members represent the base of the bridge, they had the most impact from the weight so they are made of 5 layers each. The red colored fettuccine members represent the horizontal beam that connect the two bridge frame together, they are made of 2 layers each. The pink colored fettuccine members represent the vertical and diagonal members inside the frame which functioned to support, same as the connecting members, they are made of 2 layers each. The green colored fettuccine member represents the horizontal center component of the bridge, it holds the s hook and most of the load, and so made of 10 layers. Last, the blue colored fettuccine members represent the diagonal frame of the bridge, they are made of 3 layers each because they acts as the main component to sustain the compression due to the vertical load.
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1. Beams
Figure 4.3.2 Joints of the Bridge Truss The base horizontal beams of the final bridge are made up of 5 layers of fettuccine, 4 layers vertically and 1 layer placed horizontally. The fettuccines were layered over each other using both 3 second glue and E-6000 glue. The total span of the bottom chord beams is 400 mm whereas the clear span requires 350mm. We combined 3 to 5 layer of fettuccine into each layer of the base to increase the tensile strength of the base. According to our analysis, fettuccine with shorter length has better tensile strength than the long one. Therefore, the combination of short fettuccines will result in a better tensile strength of the bridge. The precision and good workmanship also play an important role in the joining and fitting the fettuccines together to form a 400mm long base. 2. Diagonal Beam Connection
Figure 4.3.3 Diagonal Beam Connection 29
Figure 4.3.3 shows the connection within the layer of diagonal frame member of the bridge. Both end of the diagonal fettuccine members were cut diagonally at an angle to fit beam to beam connection of the frame. It is very crucial to cut directly and precisely the end of each beam as it allows the adhesive to bond the beams evenly. Thus, will create a durable and strong joint. Each diagonal beam span till about 200 mm and made up of 3 layers of fettuccine.
3. Supporting Members Connections, Horizontal Members and Centre Piece
Figure 4.3.4 Joint of supporting members, horizontal members and Centre piece
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Joint A Previous Joint Design
Improvised Joint Design
Figure 4.3.5 Joint A Connection Amendment The diagonal beams experienced the most compression due to the weight. The force is transferring diagonally up and then vertically down to the vertical member. The previous joint is very weak due to the diagonal beam to beam connection, this will create a shear force, which will break the frame easily. We changed the joint where the diagonal beams are directly connected to the vertical member. The result, the frame can hold much more of the force and therefore the load.
Joint B and Joint C
Figure 4.3.4 Load transfer at joint B and Joint C
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Joint B and C connections are similar because the members are both placed on top of each other. These joints transfer the forces directly to each other, and so are not dependent on the adhesive joining.
4.4 Final Bridge Testing and Analysis
Figure 4.4.1 Bridge before force is applied
Figure 4.4.2 Downward force on the bridge when force is applied in the middle
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Figure 4.4.3 Bottom Chord break due to tension and compression and cause the failure of the bridge.
After our observation and analysis, we concluded that the failure of the bridge is due to unevenly distributed force allocated at point A (Figure 4.4.4). The top chord could not withstand the unevenly distributed force to other member and cause it to be broken apart. The top chord experienced the most internal force compared to other component showed on figure 4.4.5. The top chord was not strong enough to withstand the large amount of internal forces created by the external downward force. The failure of the top chord is first affecting on the bottom chord as the force is directly transfer to point B from point A (Figure 4.4.4) and then the rest of the bridge. In conclusion, to improve our design, we could strengthen more on the top chord of the fettuccine bridge by increasing the amount of fettuccine layers and reducing the amount of fettuccine layers on the bottom cord of the bridge. The vertical supporting both at the end of the bridge should be removed as it does not distribute any force. Another reason for the failure of the bridge is that too much compression is in the bridge. The internal forces should be balanced out the amount between compression and tension to allow internal forces to be evenly distributed and not to be overwhelmed by compression force.
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A B
Figure 4.4.4 Force acting on the fettuccine bridge
Clear Span: 350 mm Total Length: 400 mm Height of the bridge: 75 mm Weight of the bridge: 78 g Total weight withstand: 550 g Efficiency: 387.82%
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Group Photo before the Testing of Final Bridge
Reference (n.d.). Retrieved October 8, 2015, from http://engineering.jhu.edu/ei/wpcontent/uploads/sites/29/2014/01/Spaghetti-Bridge-Construction-Hints.pdf
Steel-bridgescom, R.E.I.S.T.E.E.L. (2015). Steel-bridgescom. Retrieved 6 October, 2015, from http://www.steel-bridges.com/highway-bridge-through-truss.html
Individual Case Studies: Case Study 1: Lim Choon Wah Case Study 2: Hiew Eyang Case Study 3: Evelyn Sinugroho Case Study 4: Wong Teng Chun Case Study 5: Ling Yuan Ming Case Study 6: Alexander Chung Siang Yee
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