BUILDING STRUCTURES [ ARC 2522 ] PROJECT ONE - FETTUCCINE TRUSS BRIDGE -
Group Members: Tunku Abdullah bin Tunku Mahmood Fawzy 0901C69582 Mohammad Hafiz bin Mohd Noor Manogaran 0303984 Mohammad Harris bin Shahrul Annuar 0303768 Muhammad Naim bin Ahmad Mukif 0303348 Edner Patrick Stephen 0314623 Ahmad Ridhwan Bin Ahmad 0311384
TABLE OF CONTENTS
1. Introduction 1.1
Tension
1.2
Compression
2. Precedent Study 2.1
Principles
2.2
Joining Method
2.3
Bridge Typology
2.4
Case Study
3. Material Analysis 3.1
List of materials used in the experment and the final model
3.2
Strength of material
4. Methodology 4.1
Gluing method
4.2
Jointing method
4.3
Beaming type
4.4
Bracing types
4.5
Orientation of beam and independent parts
4.6
Provisional spacing for sanding
4.7
Provisional spacing for Cad drawings
4.8
Methods to avoid parts and the bridge itself from sticking onto the table and Gluing the bridge together
4.9
Compromising of problems
4.10
Compromising of problems and the end conclusion towards the methodology
5. Design process and development 5.1
Material Testing
5.2
Prototype 1
5.3
Prototype 2
5.4
Prototype 3
5.5
Final Design
6. Model testing 7. Final design 7.1
Changes
7.2
Flaws of changes
7.3
Advantages of changes
7.4
Cause of collapse during the final design
7.5
What were ways of improving the model that could of been taken into account?
7.6
What could have been stressed on and investigated beforehand for the final model?
7.7
Specifications of the model
8. Conclusion 9. Appendix 10. Referrences
1. Introduction As part of the studies for this project, we are required to design an effective truss bridge. From there, we are also to further analyze and calculate the forces being distrubuted and applied within each components of the bridge structure design. As for the materials, only fettuccini and glue are to be used to construct this truss bridge.
Firstly as a group, we are to conduct a precedent study on an existing bridge and analyze the way in which separate members are being joined, how the load being transferred and as well as the type of truss system employed in its overall design.
Part of the structural component of a bridge is the truss. Its is made out of three or more members where in this structural support system, the truss where the load are applied to are transmitted througout the joints so that each individual member is in either pure tension or compression.
1.1 Tension In physics, tension is the pulling force exerted by an external force on an object. It. A tension is a magnitude of force, it is measured in Newtons. (Brooks, Cole Cengage Learning. (2008). Physics for Scientists and Engineers with Modern Physics, Section 5.7. Retrieved from http://en.wikipedia.org/wiki/Tension_(physics))
1.2 Compression Compression is the application of balanced inward pushing forces to different points a material or structure, that is, forces with no net sum or torque directed so as to reduce its size in one or more directions. (Ferdinand Pierre Beer, Elwood Russell Johnston, John T.DeWolf. (1992). Mechanics of Materials: ISBN 0-07-112939-1. Retrieved from http://en.wikipedia.org/wiki/Compression_(physics))
Besides that, the amount of materials being used to construct the bridge is essential due to the fact that the efficiency rate of the structure is determined by the maximum load and the overall weight of the bridge, as shown in this formula: The efficiency rate of the bridge largely depends on factors such as the strength of the materials, and the structural analysis of the truss being employed in the design.
2. Precedent Study and Research At the beginning of this project we have conducted a study on various existing types of truss bridge. After a series of research and discussions between the group members as well as the tutor, we decided to commit with the Camel-back type. Further studies were conducted on Camel-back bridges which includes; its characteristics, history, its typical arrangement of trusses, types of joints that are often associated with this type of bridges, the materials that often being used in the construction of this type of bridges, and its applications. 2.1. Principle • • • • • • • •
Kind of Truss: Pratt Kind of pratt: Camel Back Arrangements in Camel Back Joining methods Bridge typology – its parts Examples of existing bridges Background of the bridge, history, physical strength, durability Materials: wood / steel Pratt Truss Bridge
• •
•
Pratt has diagonals in tension, verticals in compression, except for the hip verticals immediately adjacent to the inclined end posts of the bridge. Initially built as a combination wood and iron truss, but were soon constructed in iron only. How the Pratt Truss spreads out the forces when it is loaded only in the centre of the bridge:
Types of Pratt bridges: 1) 2) 3) 4) 5) 6)
Double Intersection Pratt Half-Hip Truss Parker Truss Baltimore Truss Pennsylvania Truss Camelback Truss
Camelback Truss
a. Characterized by its distinctive polygonal top chord consisting of exactly five slopes. b. Typically made out of iron. 2.2. Joining Method
2.3. Bridge Typology (Characteristics of the parts and functionality)
Arrangements in Pratt Truss (Basic) and Camelback (Variation)
2.4. Case Study Silverdale Bridge
The bridge was built in 1877, which locates in Koochiching County, Minnesota. It was designed through the style of a Camelback through truss. The length of the largest span is 162.1ft, totalling a length of 3ft. The width of the pedestrian deck is 17.1ft and has a vertical clearance of 16.0ft above the deck. This Silverdale Bridge is also known and called Zeleznikar Bridge. First, the bridge is constructed of wrought iron, which fell out of fashion long before the turn of the 20th century. Wrought iron takes much longer to corrode than steel does, and in that respect, lasts much longer (which explains the low levels of rust on the bridge). However, steel is lighter, stronger, and easier to work with than wrought iron and ultimately replaced it as the material of choice by the end of the 1800's. Second, every member of this bridge is built up with either V-lacing or lattice, features that to me makes a truss bridge much more beautiful and artistic in appearance than one made up of rolled I-beams or built-up angles. This bridge has V-lacing on both the top and the bottom of the upper chord, which also was gone by the turn of the century-most bridge builders and designers had enclosed the upper chords on all but the bottom side, using V-lacing, lattice (or X-bracing), or batten plates. The bridge's silver main chords and black intermediatverticals and diagonals add to the visual appeal. Its one-lane wood deck is in excellent condition, and the wood substructure also appears to be in good shape. The substructure and steel approaches are not part of the original structure--they were added in 1937 when the bridge was moved to this very beautiful and scenic part of the state. As of now, the bridge has been removed and is in the process of being restored in preparation of its move to Washington County, where with proper care, it should stand for another 133 years.
3. Materials and Equipments
3.1. List of materials used during the experiment and final model Materials used for the experimental model San Remo organic fettuccine San Remo fettuccine 3 seconds glue Selleys multipurpose glue UHU glue Hot glue Materials used the final model San Remo fettuccini 3 second glue Selleys multipurpose glue
Quantity 1 Packet 6 Packets 6 Bottles 4 Tubes 2 Tubes 1 Stick Quantity 2 packets 1 bottle 1 tubes
Reasons why some materials are not being used in doing the final model:1st Organic fettuccine 1. Fragile 2. Not long lasting 3. Corrodes easily 2nd UHU glue 1. Long solidify time 2. Messy 3rd Hot glue 1. Effectively increases the weight of the bridge 2. Messy 3. Decrease aesthetic value
3.2. Strength of materials As fettuccini is the only main material used for the model. We have to test it’s efficiency in terms of strength in order to achieve the criteria below. •
Aesthetic value
•
Minimal amount of fettuccine used
•
High strength to withstand load
Compression
Tension
Twisted
At first we layered the fettuccine to form one member and found that it don’t have that much of strength to withstand load. Therefore, we found another method where we join each edges of the fettuccine to form a cuboid. Like shown in figure below.
4. Methodology
As we as a group started to work on the physical aspect of the model, many problems were found in the fundamental attachment and usage of materials. Through the problems, solutions were found either through an analytical research from sources on the internet or we had compromised many options that would be taken into account. In the beginning, we studied and tested many ways to produce the perfect way to have a strong yet light independent part. This process was to enable us to save time as we did the bridge so that we wouldn't need to go back to the drawing board. Of such, these were the criterias that were looked into and furthermore added to as we did find out, that we needed to build the bridge to find these problems that were projected. Of them these were the listen methodology of each specific part during the duration of the project:
1. Gluing method. 2. Jointing method. 3. Beaming type. 4. Bracing types. 5. Orientation of beam and independent parts. 6. Provisional spacing for sanding. 7. Provisional spacing for Cad drawings. 8. Methods to avoid parts and the bridge itself from sticking onto the table and Gluing the bridge together. 9. Compromising of problems 10. End solution towards the methodology
4. 1. Gluing method.
There were several glues that were allowed to be used in the specification of weight (3 seconds glue, UHU glue and a glue gun). It was found that there were many ways on gluing the fetuccine together, each having their own strength properties. Firstly we attempted to glue it with UHU glue. That infact did not give much strenght to the fetuccine but gave its form and provision to collaborate and be strenghtened. Secondly, when using the 3 seconds glue. It was found that it did hold into place the fetuccine very well but as we combined the different members by stacking, it was not held into the place together as we did were not fast enough to mend, thus it took shape very awkardly as they were not alligned. Thirdly, using the glue gun was infact very strong but the weight gave way and glue started to bludge out of the fetuccine.
How did we solve this?
We stuck the fetuccine first, with minimal spots of UHU glue, this was to give form. After this was done, we layed it to rest and dry up until we took into the second approach to strenghted its form and durability. When it was dried and ready to start the second segment, 3 seconds glue was places along the sides of the alligned fetuccine to strenghten it. (Figure 4.1 below)
(Figure 4.1) – Steps of applying the glue
4. 2. Jointing method.
The method in which we chose to join the fettuccine together with other independent parts was a style of interlocking. (Figure 4.2 below)
(Figure 4.2) - Interlocking This method was used throughout the whole of the building of this bridge. It was found that it did not move much and had that sense of rigidness. 4. 3. Beaming type. In this segment, the beams were tested and some parts such as the vertical beams were changed for the better of the bridge, it gave a better and stronger tension compression quality. •
Upper skeletal beam and Base beam Firstly, the method in which the base and the upper skeleton of the structure did not change at all. The type of combining method was that we used 4 fettuccine sticks to stack on top of each other to form a height of 4mm and combining them gave strength. However that was for the upper skeletal beams that were places on top of the vertical beams. The base itself had taken a different approach upon. The style of which we did was a brick system, meaning that it was put into a line of 785cm of which was the total base length then stacked again in a reverse manner to ensure that the dead points were not easily broken. This proved to be strong and more rigid than alligning each other in the same manner as the level below. (Figure 4.3)
Figure 4.3 •
Vertical beams This was taken into account with stricter supervision, to maintain a better was to force its tension so that it is not easily broken. At first the beams were made with the same stacking method as the Upper Skeletal style with 3 fetuccine sticks. It did have a good strenght level but it had the tendency to bend sideways and break. This was not good as it was the breaking point of the bridge. Thus a different approach was taken. Another experiment and also advice was given from our lecturer to form a triangular shape as it will force each sides to fight against each other bringing a harder and stronger compression strenght. With much testing, it was concluded that we did the same method but in a cubic format, using 4 sticks instead of 3. This then gave a very strong handle of the vertical beam. (Figure 4.5, 4.6 & 4.7)
Figure 4.5,4.6 & 4.7
4.4. Bracing types The internal bracings between each vertical beams took the longest to figure out as angles were needed to be taken into account. The method of glueing this was stacking as well, and the way we fitted and stuck the diagonal bracings were that which we had to angle it towards each end of the connecting vertical beam, may it be at the bottom or the top. A filer or sander was used in this process to produce an exact fit. (Figure 4.8)
Figure 4.8
4.5. Orientation of beam and independent parts. After each independent, Base beam, Skeletal beam, Vertical beam and Bracing beam was made, the orientation of it was also vital part of the jointing of the whole bridge. In the first mock up, we did not take that into account and faced a problem of a lowstrenght base and skeleton usage which meant that the interlocking was useless. The bumpy face of the base beam needed to be facing up the bridge as it had a higher strength property compared to the other face that gave a flimsy effect. (Figure 4.9)
Diagram of the beams in its orientation) figure 4.9 The upper skeletal beams were also orientated the same way for uniformity in the bridge as for the strength and aesthetic value. Vertical beams were not a big problem, only that since we are dealing with a camelback trust bridge, it needed to be angled in a manner for the upper beams. This had to use the method of having a Cad plan on site as we constructed the bridge. Angles were hard to construct without the use of glue present on the fetuccine that gave strenght when sanding so it wouldn't break. It was pretty straight forward interms of angling the orientation and amount to carve. (Figure 4.10 & 4.11)
Figure 4.10
Figure 4.11 4.6. Provisional spacing for sanding. As angling came into play, it was found that it was not that easy as it seems. It needed a lot of quality control and effort to do. However, that is a separate note. The attention of this segment is to portray that as we sanded and mended the angles, it became too small and did not fit between the vertical beams at all. Leaving gaps inbetween of them, of 0.4 – 0.7 mm in space. The solution for this was that we needed to give 1 Cm provision to sand it down into fitting place. It was found affective and fitted inbetween the vertical beams very well. In facts all the beams were given 1 Cm carving space incase some did not fit, so we manually carved and sanded it for a cleaner and straighter surface. (Figure 4.12 & 4.13)
Figure 4.12 & 4.13
4.7. Provisional spacing for Cad drawings.
A butterfly or domino effect so to speak also gets tangled as everything is compromised and changed. As we gave provision to the vertical, diagonal beams, and all the other beams. It was also not taken into account that the spacing of thickness of each member was given. This gave headache to the process as everything ran everywhere and different parts of the bridge started to move. How this gave problems? (you may ask) This affected the orientation and placement of the vertical beam that stood right outside the 600mm (60Cm) mark on the table and the diagonal beams needed manual angled measurements are we could not use the drawing anymore. The method of solving this was that we measured each member as to how thick we would imagine each of them to be so that as we placed it on plan, we would not get any overlapping members that could give conflict towards each other. With proper Cad plans, our plan ran smoothly for the final design. This helped in the gluing of the bridge when in final mode of gluing it all together. (Figure 4.14)
Figure 4.14
4.8. Methods to avoid parts and the bridge itself from sticking onto the table and Glueing the bridge together
•
Problem of sticking the bridge together and solving it We decided to glue the bridge together on the table not on paper which would seem common sense now but we failed to look into that at the first prototype. In a result, we had a completed bridge that would not detach itself from the table and when we tried to force it, it broke. Leaving the mindset to innovate and compromise. As our solution, we had metal pegs to use when glueing it all together to ensure it does not stick to the table. This proved to be much better and glueing became an easy exercise. On our final model we used the pegs when gluing independent beams but used mahjong paper and the Cad paper that was placed on the wall to ensure it does not stick and that it stood straight. (Figure 4.15)
Figure 4.15 •
Allignment and avoiding an awkward angle beam from the vertical members
Problem with sticking and estimating the straighness of the vertical beams is that it does not work at all. So the bridge became bend and we had to force other members to meet so we could stick it together. For the final model, we stuck the Cad paper on the wall and stuck it there whilst using masking tape to hold the base intact with the plan. This proved to have a better effect, thus making the bridge straight. (Figure 4.16, 4.17 & 4.18)
Figure 4.16 & 4.17
Figure 4.18 4.9. Compromising gaps that were found between each joints This segment displays the use of exccess saw dust that was produced after sanding the fetuccini. As gaps were most prominent during the jointing stage of the beams, minor gaps were found which caused to question the durability and strenght of the model. As a result the use of this dust was placed to fill inbetween the gaps and then glued to harden it to strenghten the structure. (Figure 4. 19)
Figure 4.19 – Fettuccine Dust 4.10. Compromising of problems and the end conclusion towards the methodology It was found that the methodology for each different segment had to be improved and compromised as problems arose along the way. Nevertheless, each compromise gave a better quality control towards the building of this model with the methodology used.
5. Design Process and Development
5.1. Material Testing As the decision of the bridge type have been made and agreed upon by all group members, the next stage was the testing of the strength of different types (organic and non-organic) and brands of fettuccines. The method of conducting this test was by applying a load on one end of the fettuccine and put the other end in a fixed position. The result of the test was measured by the maximum amount of load that can be applied to the fettuccines before it broke. The test showed that all types and brands have different but similar amount of strength from one another, however the little differences were not to be undermined therefore after a discussion between the group members, the non-organic fettuccine was chosen to be used for the bridge construction. Further discussion was conducted in order to decide on the design of the bridge and also the joining methods of each part to the others. 5.2. Prototype 1 The first prototype was a complete one-side of the bridge, where the slightly darker and greenier in colour organic fettuccine were used as for the construction of the bridge, this is due to the sole purpose of this process was to how the bridge would have looked like, how effective the joining methods would be, how it wound balance and most importantly what kind of problems we would have encountered during the whole process of making the bridge so that we could raise the matters for the next discussion session. During this process, jobs were delegated in a way where some of the group members worked on filtering the fettuccines to ensure that and flawed ones would not be used for the construction of the bridge, some worked on figuring out the method of joining the X braces, while the others worked on the cutting and assembly of the whole bridge. During and after the process stated above, we have identified several issues that we have encountered during the assembly and post assembly process, most of which were not anticipated by the group members. The issues include; the height of the bridge were too tall, as well as the whole dimension of the bridge needed to be further enhanced, the orientation (sideways instead of upwards) of the base were causing the structure to be weak, and the mixture of glues (super glue and UHU glue) were causing some kind of chemical reaction a several hours after the assembly process. As for the X braces, several methods were explored and one of the method were proven to be fairly strong, however the process of making one X brace of that method were very time consuming which raised questions on the time planning.
5.3. Prototype 2 Armed with new knowledge and experience gained from the first design, a more careful planning were conducted to avoid encountering the same problems that was encountered from the first design. At this stage, plan was digitally drawn as well as the base layout of the bridge as guidance during the assembly process. Several changes were made based on the issues that were encountered from the first design. Changes include; reduce of height (by 20mm), distance between one column to another, the material (non-organic fettuccine) and the use of glue (strictly no mixing). This prototype made to the stage of both sides being completed but were not assembled together to form a bridge due to the total weight of both sides exceeded the weight quota. However this design gave an idea of how stiff and strong the design was, therefore it justified the choice of sticking with the design, however several changed needed to be made in order to reduce the total weight of the bridge.
5.4. Prototype 3
At this stage of the project, a complete bridge was to be built in order to conduct a test-to-fail experiment. Further changes and enhancements were made from the previous design which include; the hollow beams instead of solid-sandwiched beams, reduced the X braces from four on each side to two in order to save time and weight, the height were reduced as well as the length. The design made it to its completion, a 5-layered piece of fettuccines were placed in the middle of the bridge which spanned from one side of the bridge to another. The purpose of this piece was to hold the load by the S hook. Load was placed one by one till it reached 4.5kg when the 5-layered piece broke at the point where the S hook was resting on as shown in the image below.
5.5. Final Design As for the final design, a discussion and a careful planning were conducted prior starting on the actual design. Careful measurements were calculated and produced which were then reproduced on AutoCAD with the consideration of the thickness and dimensions of each member. This is due to the inconsistency in angles and few millimetres in dimension that were encountered during the previous designs which were caused by the failure to include the thickness and the dimensions of the
members, all drawings that were produced prior to this stage were drawn in a form of single lines. Furthermore, in order to reduce the weight of the bridge itself, further changes were made. Changes include; the reduction in height of the bridge, reduction of the layers for the outer structure, the reduction in the width of the bridge (the distance between one side of the bridge to the other: from 80mm to 60mm), and the X braces were removed all together and were substituted with the normal braces. Different approach was also taken in order to minimalize errors in angle, dimension and joints which could cause weakness or failure. The changes in approach are as such; each member were cut and shaped into a precise dimension according to the CAD drawing, the members were glued to the precise position as according to the CAD drawing.
6. Model Testing •
Testing of model 2 time lapse
At 1.2 kg point load (Figure above) •
The fettucine bridge still standing strong. At 1.8 kg point load (Figure above)
•
The fettucine bridge still showing a positive sign and look like it can withstand more than 1.8 kg.
At 2.4 kg point load (Figure above) •
The fettucine show a little bit of vibration when the load is released. At 3 kg point load (Figure above)
•
The fettucine still vibrate a little bit but it still can withstand more load.
At point 3.6 kg and 4.2 kg point load (Figure above) •
The bridge look more tension and produce more vibration.
At point 4.8 kg and 5.4 kg point load (Figure above) •
The middle part (that hangs the load) looked stress but the rest of the bridge only show sign of vibration but it still look stiff.
At point 6 kg point load (Figure above) •
The load still look stiff and steady to hold 6kg but there is serious vibration from the middle hanging part.
At point 6.6 kg point load (Figure above)
•
The load breaks the middle part of the bridge but the bridge it self doesnt collapse.
– Conclusion of the test:
– The bridge still can holds a lot of load because the important structural members are still intact.
– The only failure at 6.6 kg is the hanging part which breaks into half.
– The joining, bracing, and vertical members work and connects well to distribute the load uniformly.
7. Final Design
7. 1. Changes Towards the final implementation and changed of the design, much was changed towards the style and structure of the model. The height was decreased and the diagonal trust bracings were altered to decrease the weight of the bridge. The amout fetuccini used in each individual beams were reduced by 1. The horizontal spacing between the bridge was also reduced to save weight for the total structure. Used fetuccini dust to filled in the gaps that were seen and made unstable. 7.2. Flaws of changes •
Reducing horizontal beam spacing between bridges meant that it was more prone to twisting and collapse.
•
The fetuccini dust made the weight of the bridge heavier of sorts.
•
Gave way more weight despite the subtraction of fetuccini sticks.
7.3. Advantages of changes •
Made the structure more rigid.
•
Precise spaces between vertical beams.
•
Vertical beams were upright and it was easier to joint other parts.
7.4. Cause of collapse towards final testing •
The horizontal beams were too close to each other.
•
The horizontal joints were not joint inbetween bridges, instead it was placed ontop of both bridges which caused the pressure to snap it. 3 seconds glue was put that gave way to bending of the structure which infact made it unstable in the first place. (Only to find out in the end)
•
7.5. What were ways of improving the model that could of been taken into account? After conducting the test on the final bridge model, we also analyzed that there were some factors that could be further improved if given the opportunity to further develop on the study of the bridge strength. One of the factors that affect the final model not to withstand an even heavier weight would be the fact that none of the parts of the bridge were perfectly assembled. To support this, human craftsmanship has the tendency to do be varied to one another.
From step to step, it started from the measuring the length of each part of the fettuccine where the measurements would be differs depending on the eye level of the
person who measured it. Then comes to the part where we needed to cut the fettuccine pieces. The problem here was that the way we cut the fettuccine pieces could have affected the overall strength of the parts. This is because it created a hairline fractured which is not visible to the human eye to detect. We believe we could have improved this by using AutoCAD to get the exact measurements of each fettuccine parts we needed and using laser cutting to get the precision in the cutting without any flaws to affect the strength of the final bridge design. Other than that, we found out that the gluing method by using the ‘3-Second’ Glue could have corroded the fettuccine parts at some important joints. Perhaps the excessive use of that particular glue could have also affected the extra weight of the bridge. This would be improved if we took precaution onto the application of the adhesive by ensuring both surfaces of the fettuccine joints to be smooth, clean, dry and free from oil, grease, etc. Aside from that, during application of the adhesive, we should applied one drop every 1-2 centimetres and spread it evenly. Aside from that, we also could make sure the bond was strong by applying slight pressure on the joints. To ensure best results on this, leaving it overnight at room temperature would be the best option to allow it to be completely hardened. 7.6. What could have been stressed on and investigated before hand for the final model? Having the final bridge model tested to analyze the effectiveness of its efficiency, we should take into account some things we could have emphasized and figured out before conducting the test. Despite the flaws of the model, it contributed to the study for us to learn in the future if we are to conduct another project dealing with the same situation. Firstly would be the matter of time management where we could have prepared a contingency plan in case anything happen during the assemble of the final model. The reason is because some unavoidable factors such as the parts breaking apart during the assemble gives a delay in providing a better workmanship in the model. Aside from that, we should have conducted various tests on how we could lose more weight on the bridge. We could have lost weight on the final model if we
are to figure out and test different methods of columns, gluing, testing, bracing, etc.
Furthermore, we figured that we should have further inspected on each step taken to assemble the final model together. Having this done, each stages to construct the bridge, from cutting to gluing it together would have been checked by each members and if any there is anything wrong in any of those stages. 7. 7 Specifications of final model •
Height - 120mm
•
Weight - 190g
•
Length - 750mm
•
Amount of weight withstood - 5kg
•
Amount of trust used – 10
Calculations of the bridge
2J=M+3 2(22)=41+3 44=44 therefore it is as perfect truss bridge. ΣFX=0 AND ΣFY-0
At join L a force of 25N is being applied downwards on each façade as a load of 5kg is hung at point. Consider that a force of 15N is evenly distributed on either side of the bridges. The joint A force of 12.5N acting upwards. At joint A
ΣY=0 12.5+FAB(Sin39)=0 FAB(Sin39)=-12.5 FAB= 19.86 FAD+19.86(COS39)=0 FAD=19.86(COS39) FAD=-15.4N
At joint B FBC(Cos39)+15.4=0 FBC=-19.81N FB2+19.86(COS39)= FB2=-19.86(COS39) FB2= 15.4N
At joint C ΣX=0 ΣY=0 -FCD-1981(SIN510=0 FCE=25N FCE(COS15)-19.81=0 FCE(COS15)=19.81
FCE=20.5N At join D 15.4-FDB(COS39)=0 -FDB(COS39)=-15.4 FDB =19.81N
FDF-15.4+19.81(SIN51)=0 FDF=30.8N
At Joint E ΣY=0 ΣFX=0 -FEF-20.5(SIN75)=0 -FEF=20.5(SIN75) FEF=-19.80N -19.80-FEH(SIN43)=0 -FEH(SIN43)=19.80 FEH=29N FEG(COS15)+19.8=0 FEG(COS150)=-19.8 FEG=20.5N
At joint F FFH-30.8+19.8(SIN31)=0 FFH=10.4N
8. Conclusion
Throughout this project we are now able to understand how structures works. We learnt how every structural members need to be taken into consideration before building it as each of the parts play an important role and we also learnt how
force are being applied in tension and compression. The truss bridge model is a success as we get to minimize the amount of material used. Throughout the process building the test model and the final modal first we produce a cad drawing as a reference. We took it very seriously in cutting the length where at first we gave provision so that we could file it. Furthermore, for the joining parts the angles are actually precise because we trace it from cad drawing. We also found that the gluing method is also important because in terms of workmanship it will affect the aesthetic value and the to much glue will also increase the weight of the model where it already defeat the purpose because our aim is to built lightweight truss bridge that able to withstand heavy load. We must follow the right methods in order to become a good architect especially in working world so that we could contribute to the society and the planet. Efficiency Conclusion Case study number three is the most effective because all of the critical members shares the same amount of force and it is at minimum value compared to others.
10. References
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