PROJECT 1: FETTUCCINE TRUSS BRIDGE

Transcription

1 ARC 2523 BUILDING STRUCTURES PROJECT 1: FETTUCCINE TRUSS BRIDGE SCHOOL OF ARCHITECTURE, BUILDING AND DESIGN, TAYLOR S UNIVERSITY LAKESIDE CAMPUS TUTOR: MS. ANN CHUAH SAY YIN CHRISTINE YEAP ZHE XING KHOR XIN SUAN NG WEI YING WANG PUI YEE

2 CONTENT Page 1.0 Introduction 2 1.1Project Intention 1.2Report Overview 2.0 Methodology Aim of Study 2.2 Learning Outcomes 2.3 Precedent Study 2.4 Materials and Equipment Testing 2.5 Model Making 2.6 Structural Analysis 2.7 Bridge Efficiency Calculation 3.0 Precedent Study Material and Equipment Material 4.2 Equipment 5.0 Modal Making Process 5.2 Precautions 6.0 Structural Analysis Member Analysis 6.2 Design Analysis 7.0 Conclusion Appendix References Exercise: Truss Analysis 41 1 P a g e

3 1.0 Introduction 1.1 Project intention and research In a group of 5, we were required to design and construct a truss bridge with fettuccine. The bridge requirement include a clear span of 750mm and maximum weight of 200g. The fettucine structure will be tested to fail. The bridge must be of high efficiency by using the least material to sustain the higher load. The intention of designing this bridge is to investigate and understand the tension and compressive strength of construction materials. In this case, it's the fettucine. We are required carry out research on precedent studies of bridges with different truss system. There 6 types of bridges identified through extensive research. Namely, the Beam bridge, Truss Bridge, Arch Bridge, Suspension bridge and Cantilever Bridge. For this project, only truss bridge is needed to be analyzed as the project requirement is to build a truss bridge with high efficiency. Materials are being experimented to differentiate its strength. Several brands and types of adhesives are used in the test to determine its strength and properties. Through this project we are able to identify which member in the truss system needs to be strengthen so that the load apply will be distributed evenly throughout the entire system. 1.2 Report Overview The report started off with a precedent study carried out on a truss bridge. Analysis of load distribution and how it affects its member. The report also recorded down the several designs we had tried out before the deciding on the final design. These test bridges were improved and developed further based on previous test results and analysis to increase its efficiency. A set of analysis regarding the strength of the bridge structure and its reason of failure had been done. Individual case studies calculations are attached at the end of the report. 2 P a g e

4 2.0 Methodology 2.1 Aim of Study The aim of this projects is to develop student's understanding of tension and compressive strength of construction materials as well as the force distribution in a truss. This project aims to enable students to design a perfect truss bridge which fulfills the aesthetic value and minimum construction material required. 2.2 Learning Outcomes By the end of this project, students are 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 - Explore different arrangement of members in a truss structure 2.3 Precedent Study We had opted to carry out our case study on the Cicero Avenue Cal-Sag Bridge. This bridge is the closest to what we had for our fettucine bridge in terms of design and truss member arrangement. Further elaboration and findings will be in the Precedent Study section later. 2.4 Materials and Equipment Testing We had experimented with different brands and types of fettuccine to examine its tension and compressive strength before deciding to select a specific brand to proceed with our bridge building. The brand of fettucine we had selected in this project is San Remo. Various types of adhesive are being used in the experiment and were observed how they affect the joints and connecting members of the bridge. In the end, we settled on super glue (3 seconds glue). 2.5 Model Making The model making process was an on-going process as we had to keep revising and improving the Fettuccine Bridge after load testing to achieve higher efficiency. A total of 6 bridges with various designs and improvements were built for this project. After testing, the strength of each bridge will be maintained and the weakness will be eliminated for further development. 3 P a g e

5 2.6 Structural Analysis Structural Analysis is the determination on the effects of load on the Fettuccine Bridge and its members by calculation. 2.7 Bridge Efficiency Calculation The efficiency of the bridge tested is calculated using the formula: Efficiency,E Maximum Load Weight of bridge 2 4 P a g e

6 3.0 PRECEDENT STUDY CICERO AVENUE CAL-SAG BRIDGE Cicero Avenue Cal-Sag Bridge is a truss bridge through Calumet Sag Channel at Cicero Avenue, Illinois. It was built in the year 1938 and was rehabilitated on year It is one of the oldest existing metal truss bridges among the truss bridges on Calumet Sag Channel and Little Calumet River. According to the bit letting in November 2011, the bridge is planned to be rehabilitated again of which the works include painting, repair of gusset plate connections, joints repair, etc. The truss bridge function as a four lane vehicular bridge with 2 pedestrian passage at each side. Figure 3.1: West Elevation and Top View of the Bridge The type of this truss bridge is warren truss. It is the type of truss that contain a series of isosceles or equilateral triangles. In the case of Cicero Avenue Cal-Sag Bridge, vertical members 5 P a g e

7 are added to increase the span of the bridge. The total length of this bridge is 115.2m with the span of 82.3m, deck width of 13.3m and vertical member of 5.3m. Besides, top chord and end post is also riveted with an additional plate as shown in box A in figure 2 to strengthen the its box beam. C B A B Figure 3.2: Connections of Top Chord, Bottom Chord, Vertical Member and Diagonal Member Figure 3.3 Figure 3.3 is showing from the interior view of the bridge the part labelled as B in Figure 3.2. It is the connection joint among diagonal members, vertical member, struts and lateral bracing son the top as well as top chord or bottom chord. They are joined together by riveting to gusset plates. 6 P a g e

8 Figure 3.4 is showing the part labelled as C in figure 3.2. It is the connection joint of the vertical member to the top chord. Figure 3.4 A B Figure 3.5: Interior View of the Bridge Figure 3.6 is showing the part labelled as A in figure 3.5. It is the connection joint of the lateral bracings and struts through gusset plate. Figure P a g e

9 Figure 3.7 is showing the part labelled as B in figure 3.5. It is the connection joints of the members of portal bracings. Its connection system is the same with sway bracings except having different arrangement of the truss. Figure P a g e

10 4.0 Material and Equipment 4.1 Materials Type of Adhesives Advantages Disadvantages - Able to adjust position of connection as it dries slower - Flexiblele connection - Easy to use -Causes the bridge to weight more -Needs more amount to stick the members tightly UHU Glue -Efficient -Easy to use -Does not hold the members tightly UHU Superglue -Highest efficiency -Firm and stiff connection - Easy to use -More brittle: broken easily if fettuccini is not stacked in multiple layers 3 Seconds Glue (Superglue) Table Initially, we use both UHU and 3 seconds glue as we think that both are able to counter the compression and tension we might need flexibility in certain members and used 3 seconds glue on horizontal members at the base to have the best strength to hold the whole bridge together. Then we switch to UHU super glue as flexibility in using UHU is unnecessary and is less efficient. Finally, we have chosen to use only 3 second glue as it dries faster which could save up a lot of time in model making as this project need us to test on multiple bridge design before finalizing on the selection of design. 9 P a g e

11 We had selected two different brands of fettucine to carry out the material load testing before selecting one of it for the bridge construction later. The difference between San Remo brand fettucine and Kimball brand fettucine is the width. Sam Remo fettucine is measured at 5mm whereas Kimball fettucine is measured at 4mm. Load testing is then carried out to determine the tension and compressive strength of each brand. Figure San Remo Fettucine Figure Kimball Fettucine Material Load Testing Results: San Remo Fettucine I-beam Laminated truss Weight One pail and 600 g One pail and 200 g Kimball Fettucine I-beam Weight One pail Load testing results proved that San Remo s fettuccini is stronger than Kimball s fettuccini. It is compared in the condition where the glue used and the way of lamination is the same. San Remo brand is selected in the end. 10 P a g e

12 4.2 Equipment Figure Penknife Figure Scissors Penknife is able to cut precisely and accurately compared to using scissors. Fettucine are prone to breakage as it is very brittle. Therefore, penknife is a better choice for cutting Figure Nylon String Figure Raffia String Nylon string is chosen to hang the pail of water from the bridge rather than raffia because it is more durable. Figure T-Square Figure Set Squares 11 P a g e

13 Figure Metal Rule Set squares were used to ensure the vertical member sticking to the horizontal member is at right angle. T-square and metal rule are used to mark the measurement as it can reach longer length, which increase the accuracy of the measurement Figure Sand Paper Sand paper is used to mill the edge of the fettuccini in case it is not cut well. This is important as the contact surface of fettuccini should be maximum as it could affect the load it could carry and the better the joint connection, the more stable it could be. 12 P a g e

14 Figure Pail Figure S-hook Pail is used to fill the water which act as load pulling downwards from the bridge with an S- hook connecting to the bridge. Figure Electronic balance An electronic balance is used to get a more accurate weight measurement. 13 P a g e

15 5.0 Model making 5.1 Process 1. Categorize the fettucine into usable and non-usable. (bent or straight) 2. Draft out the design of the bridge in AutoCAD and print out the drawings of the bridge. 3. Measure the fettucine and cut them into the specific lengths. 4. Make all the components and turn them into I-beams or laminated truss with adhesive. Figure I-beams and laminated trusses are constructed precisely 5. Join the vertical components to the base strip as seen in Figure P a g e

16 6. Place the bracings in between the vertical components. Figure Stick the top chord for both sides of the bridge. Figure P a g e

17 8. Connect both sides of the bridge horizontal I-beams. Figure Continue by fixing horizontal components on top to hold both sides of the bridge. Figure P a g e

18 10. Place the two major supporting beams in the middle. Figure Weight the bridge. Figure P a g e

19 12. Test the bridge. Figure Identify the weakness and problems. Figure Repeats the steps above until the final model. 18 P a g e

20 Model 1 Figure Model 2 Figure P a g e

21 Model 3 Figure Model 4 Figure P a g e

22 Model 5 Figure P a g e

23 5.2 Precautions Overall aspects: 1. Quality controls is needed for fettucine. There are twisted and bended fettucine which will affect the stability and strength of the bridge. Figure shows the examples of a straight and bended fettucine 2. In order to make sure the bridge functions as how we plan, we need to build the model as perfect as the drawing. We can use setsquares to make sure the fettucine are joined perpendicular to one another. 3. Place cardboard on the table when using 3 seconds glue in order to prevent the glue from staining the table. 4. When using 3 seconds glue, make sure the position of joint and stick it quick and accurately. Remember try not to readjust the position because when there is a layer of glue on the fettucine, it will be tricky to stick them precisely again. 5. Make sure the finger is not near to the place where u apply glue because when removing the finger after holding the fettucine in its position might cause destruction of the joints of the fettucine itself. 22 P a g e

24 6. Reapply glue to every joint. Joints: 7. Test the completed bridge a day after construction to make sure the glue has set in. a) Make sure the fettucine join firmly with each other. Use sand paper to make sure the end of the fettucine is flat and even in order to prevent the uneven surface of the fettucine when joining to one another which would affect the strength of joints. b) When assemble the components into a bridge, it is better to have four people so that those components can be held in position and join firmly. c) In order to make sure the fettucine joins firmly, it is better to join it in a way which the two fettucine members have the most surface contact. Diagrams below are the examples. Example 1: (a) (b) Joint (a) will sustain the weight solely based on the glue whereas joint (b) will transfer the load through the connection. Therefore, joint (b) is a better choice. 23 P a g e

25 Example 2: (a) (b) Joint (a) has larger contact surface area compares to joint (b) which make it a better choice for making the bridge. Example 3: (a) (b) Joint (b) has larger contact surface area compares to join (a) which enable it to hold both of the bottom strip together firmer than join (a). 24 P a g e

26 Example 4: (a) (b) Joint (a) has more contact surface area and a more flat contact surface compare to joint (b) which mean it can be join much more firmly. Therefore, it is better to choose joint (a) over joint (b) as this is an important joint for bracing which is an important member in supporting the bridge. 25 P a g e

27 6.0 Structural Analysis 6.1 Member Analysis Experiment of various designs of Fettuccini members tension and compressive strength with load. The members were tested to bear with load for 10 seconds during each experiment. Each members had 160mm clear span and 350mm resting on table at each end. Type of member Weight C beam 300 g 500 g Broken - Bent Bent Bent Bent Bent Broken Laminated Broken - I- beam Bent Bent Bent Bent Bent Broken Bent Broken Bent Broken L- beam Broken - Triangular Bent Bent Bent Broken Table In conclusion, the double layered I-beam is the most stable although it contributes the most weight. 26 P a g e

28 Further experiments are then carried out to test how different choice of adhesive affect the performance of the truss. Double layered I-beam of 160mm clear span is used in this experiment. Adhesive 800g 900g 1000g 1100g 3 seconds glue Bent Bent Bent+ broken - (18s) UHU + 3 seconds Bent Bent Bent Bent+ broken glue (7s) Table The test is carried out further with double layered I-beam with clear span of 160mm placing vertically on both side of the desks. The adhesive used to construct the I- beam is 3 seconds glue 800g 900g 1000g 1100g 1200g Not bent Not bent Bent Bent Broken Table P a g e

29 6.2 Design Analysis Fettuccine Truss Bridge Design 1 Figure (a) *Assumption Made Figure (b) Total Length: Weight of Bridge: Clear Span: Load Sustain: 950mm 230g 750mm < 1400g Efficiency: < Figure (c) Cross section 28 P a g e

30 Figures Problems encountered: 1) Too many members at one joint does not help to transfer load. 2) The bridge is overweight with low efficiency. 3) The upper members are not strong enough to overcome compression. Solutions: 1) Change the connection of slanted members with vertical members. 2) Reduce the length of connecting beams to reduce weight of the bridge which does not exceed 200g. 3) Replace two-layer laminated with I-beam for upper members and vertical members to increase the strength. 29 P a g e

31 Fettuccine Truss Bridge Design 2 Figure (a) *Assumption Made Figure (b) Total Length: Weight of Bridge: Clear Span: Load Sustain: 950mm 233g 750mm < 1000g 30 P a g e

32 Efficiency: < Figure (c) Cross Section Figure Problems Encountered: 1) The internal bracings are too long and weak to resist force. 2) Failure on joints. 3) Horizontal members broken. The surface in contact with vertical member is low therefore load cannot be transferred. 4) Upper members are too weak to sustain load. Solutions: 1) Reduce the length and increase the thickness of internal bracing. 2) Perfect edges on fettuccine to allow perfect joining. 3) Change the orientation of I-beams. 4) Replace two-layer laminated with I-beam for upper members and vertical members to increase the strength. 5) Change the orientation of slanted members for better load distribution. 31 P a g e

33 Fettuccine Truss Bridge Design 3 Figure (a) *Assumption Made Figure (b) Total Length: Weight of Bridge: Clear Span: Load Sustain: 950mm 340g 750mm 3860g Efficiency: Figure (c) Cross section 32 P a g e

34 Figure Changes made refer to previous designs: 1) Vertical and upper members are changed to I-beams. 2) Length of connecting beams reduced. (shown in section) 3) Height of the truss bridge reduced. 4) Internal members increases. Problems Encountered: 1) Connecting beams could not sustain higher load. 2) Weight of the structure exceeds 140g. 3) The efficiency is still not satisfying. Solutions: 1) Replace some of the members with two-layer laminated to reduce the weight. 2) Increase the spacing of the internal members to reduce material used. 3) Add horizontal beams onto connecting beams to sustain higher load. 33 P a g e

35 Fettuccine Truss Bridge Design 4 Figure (a) *Assumption Made Figure (b) Total Length: Weight of Bridge: Clear Span: Load Sustain: 950mm 354g 750mm 5200g Efficiency: Figure (c) Cross Section 34 P a g e

36 Figure Changes made refer to previous designs: 1) Height of truss bridge reduced. 2) Internal members reduced. 3) Horizontal beams added onto connecting beams. 4) Length of connecting beams reduced. Problems encountered: 1) Failure on joints. 2) The structure has sustain its maximum load but efficiency still not satisfying. 3) Weight of the structure still exceeds 154g. Solutions: 1) Have all the connecting beams join directly perpendicular to the vertical members to improve load distribution. 2) Reduce the number of layers in less critical members. 3) Reduce the height and length of connecting beams. 35 P a g e

37 Fettuccine Truss Bridge Design 5 (Final Design) Figure (a) *Assumption Made Figure (b) Total Length: Weight of Bridge: Clear Span: Load Sustain: 950mm 225g 750mm 5750g Efficiency: P a g e

38 Figure (c) Cross Section Figure Apparently, the efficiency of our last design is the highest among the previous truss bridges. 37 P a g e

39 7.0 Conclusion By the end of this project, we had constructed a total of 5 fettucine bridges to achieve the highest efficiency possible. The precedent study of Cicero Avenue Cal-Sag Bridge had help us to understand how load is distributed in a truss bridge system. Our final model of the bridge is constructed in perfect frame system and achieved the highest efficiency among the 5 bridges. The efficiency calculated for our final bridge testing is This project has made us understand more about load distribution in a structure. We also learned to calculate the efficiency and type of force applied in each structural member. We had also experimented with various truss and beam deigns in order to select the best one for our bridge construction. We understood the importance of the diagonal bracing member. Therefore, these members are heavily strengthen using double layered I-beams. The precision of each connecting joints were achieved as we had built the bridge based on the computer aided drawing we had prepare. Each connecting point were milled evenly using sand paper to prevent imperfect connecting joints. This project required quite a period of time as we had to go through a couple of trial-error. The bridge building process was long and tedious and required lots of patience putting the whole thing together. But it never fail to amaze us how a non-construction material like the fettucine is able to withstand load after proper designing and structural analysis. All in all, it was a great learning process, regardless of how tedious the building process might be. We learnt a great deal in proper structural design and it will definitely us in creating a building with proper building structure for future projects. 38 P a g e

40 8.0 Appendix A group photo taken during final load testing. 39 P a g e

41 9.0 References Cicero avenue cal-sag bridge. (2011). Retrieved from Kathy, W. (2007, 2 27). Cicero avenue cal-sag bridge. Retrieved from Vincent T. H, C. (n.d.). What are the differences among warren truss, howe truss and pratt truss?. Retrieved from 40 P a g e