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Assignment 3 6504

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Assignment 3 6504

  1. 1. ASSIGNMENT/ASSESSMENT ITEM COVER SHEETStudent Name: Donald HEATHER FIRST NAME FAMILY / LAST NAME 2 0 0 8 8 0 9Student Number: Email: donald.heather@det.nsw.edu.au Course Code Course Title E D U C 6 5 0 4 Engineering Education Studies 1(Example) (Example) A B C D 1 2 3 4 Intro to UniversityCampus of Study: Callaghan (eg Callaghan, Ourimbah, Port Macquarie)Assessment Item Title: Engineering Scenario Due Date/Time:Tutorial Group (If applicable): Word Count (If applicable): 1700Lecturer/Tutor Name: C HollisExtension Granted: Yes No Granted Until:Please attach a copy of your extension approvalNB: STUDENTS MAY EXPECT THAT THIS ASSIGNMENT WILL BE RETURNED WITHIN 3 WEEKS OF THE DUE DATE OF SUBMISSION Please tick box if applicable Students within the Faculty of Business and Law, Faculty of Science and Information Technology, Faculty of Engineering and Built Environment and the School of Nursing and Midwifery: I verify that I have completed the online Academic Honesty Module and adhered to its principles Students within the School of Education: "I understand that a minimum standard of correct referencing and academic literacy is required to pass all written assignments in the School of Education; and I have read and understood the School of Education Course Outline Policy Supplement, which includes important information related to assessment policies and procedures. I declare that this assessment item is my own work unless otherwise acknowledged and is in accordance with the University’s academic integrity policy available from the Policy Library on the web at http://www.newcastle.edu.au/policylibrary/000608.html I certify that this assessment item has not been submitted previously for academic credit in this or any other course. I certify that I have not given a copy or have shown a copy of this assessment item to another student enrolled in the course. I acknowledge that the assessor of this assignment may, for the purpose of assessing this assignment: Reproduce this assessment item and provide a copy to another member of the Faculty; and/or Communicate a copy of this assessment item to a plagiarism checking service (which may then retain a copy of the item on its database for the purpose of future plagiarism checking). Submit the assessment item to other forms of plagiarism checking. I certify that any electronic version of this assessment item that I have submitted or will submit is identical to this paper version. DATE Turnitin ID:STAMP (if applicable) HERE Signature: _____________________________________________________________ Date: ___________________Insert this way
  2. 2. D. HEATHER - C2008809 CONTENTS PAGERESEARCHCurrent pylon technology-P3Types of trusses-P3Types of pylons-P5Forces on pylons-P6Why use a truss-P6Joining methods-P7Test methods-P7Design and development-P8Results and conclusion-P17Bibliograpthy-P18 Page | 2
  3. 3. D. HEATHER - C2008809 RESEARCHCurrent Pylon TechnologyPylon is the Greek term for monumental gateway of an Egyptian temple. A pylon is usuallytapered from bottom to top to support something like power lines. A transmission tower is a tallstructure used to support power lines usually made out of steel lattice. The four main functions oftowers are suspension, terminal, tension and transposition towers. The towers have prototypestested at tower-testing stations. The towers can be assembled on the ground and then erected usingpush pull cables. Assembled vertically helicopters can be utilised as aerial cranes.Pylons can also be used to support bridges, and can reach heights that rival some of the tallestbuildings. They are used in suspension bridges and cable staged bridges. The use of the pylon, asa simple tower structure, has also been used to build rail road bridges. TYPES OF TRUSSESWarren TrussThe warren truss was patented by James Warren in 1948. It is one of the most popular designswhich use equilateral triangles to spread out the load on the bridge. The forces on the membersare minimalised due to the triangles being in compression and tension. As a load moves over thebridge sometimes the forces switch in the members from compression to tension. This happensespecially to the members near the centre of the bridge.. Page | 3
  4. 4. D. HEATHER - C2008809Pratt TrussPratt trusses have the vertical compression members and diagonal tension members. The endmembers are the only ones that do not slope towards the centre of the truss configuration. Thediagonal members are subjected to tension forces only so they can be thinner allowing for a moreeconomical design.Howe TrussThe Howe Truss is the opposite of the Pratt Truss with the diagonal members slanting towards theclosest bridge end. These members are subjected to compressive forces which necessitate largesteel members. This makes this type of truss uneconomical for steel construction. Page | 4
  5. 5. D. HEATHER - C2008809 TYPES OF PYLONSPylons are tower-like structures that support antennas or electrical cables, or used as the verticalsupport for a bridge or a tower.Lattice TowerThese towers are made from steel and are a very practical type of pylon. They can be climbed byhand to be serviced or modified and are easy to maintain. Different types of pylons do not allowfor climbing so the need to service the pylon must be done by crane or by lifts.Monopole.A monopole pylon is a single tall pole with an antenna on the top.Wired PylonsIf a single pole pylon becomes extremely tall then supporting cables are connected in eachdirection around the pole to stabilise it. Wired pylons are also called guyed towers.Electric PylonElectric pylons are designed on the lattice tower model, with two or three sets of vertical arms tohold the wires.Bridge PylonsSuspension bridges use the pylons as tall supports that hold up the cables of the bridge. They areconstructed deep into the ground, with large concrete foundations. Pylons may be positioned ateither side of the bridge providing a formal entrance.Egyptian PylonsPylons in Egypt were large structures that marked the entrance to temples. They were strongenough and high enough to provide a defensive barrier. Page | 5
  6. 6. D. HEATHER - C2008809 PYLONS IN CIVIL STRUCTURESPylons are utilised on civil structures to support a variety of needs.Bridges: used to support the base of the bridge or be utilised to hold cables to support the bridge.Power Lines: used to support power lines in different configurations and quantities of lines.Aeronautics: used to support structures on aircraft such as navigation equipment.Telecommunication: used for many types of electronic communication including radio, EMSservices, cellular and global positioning satellite technology. FORCES ON PYLONSAxial force – is the tension or compression force acting on a member. The axial force actsthrough the centroid of the member and is called concentric loading. If the force does not actthrough the centroid it is called eccentric loading. Eccentric loading produces a moment in thebeam because the load is a distance away from the centroid.Radial Forces-This is a force that is exerted perpendicular to the centreline, or axis of an object. WHY USE A TRUSSA truss is a frame made up of a number of members, generally arranged in triangular units,through which forces are transmitted to the joints called nodes. (Rochford, 2011)Truss members need to be long and slender, the moments transmitted to these joints are negligibleand the nodes can be considered as hinges. Trusses are stronger than other structures becausenearly every material is much stronger in compression and tension than shear, torsion or bending.Truss design pylons can be constructed on the ground and then lifted into position which is costeffective. Page | 6
  7. 7. D. HEATHER - C2008809 JOINING METHODS OF TRUSSESGussit plate-A gusset plate is a steel sheet that is used to connect beams and girders to a column orto connect truss members to the top or bottom plate. They can be fastened to a permanent memberby rivets, bolts or welding. They serve to join the members together and strengthen the joint in theprocess.Gang nails-Roof trusses can have gang nails in the nodes. These are made out of galvanised steelto resist rusting and are hammered into members at the join. TEST METHODI used a piece of steel clamped to the table with a long range dial indicator. The dial had amagnetic base to secure it in position. I placed a piece of wood on the moveable jaw of the vice togive me some height to allow indicators to rest up against. I then fitted the pylon, set the dial onboth zeros. The dial was set on zero and the clock dial was also on zero. As the vice was woundin I could measure how far and feel the pressure needed to overcome the initial resistance, theflexibility of the structure and finally failure length in mm. When I was winding I could feel theresistance in the pylon, when the pylon members began to bent I could feel the pressure needed onthe vice handle decrease until the structure finally fractured. I had time to stop winding the viceand read the measurement on the dial indicator at these three points in the exercise.Vice with dial set up to take reading. Page | 7
  8. 8. D. HEATHER - C2008809DESIGN AND DEVELOPMENT Page | 8
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  14. 14. D. HEATHER - C2008809 DESIGN 1 I tried to construct a simple design to complete the task. Difficult to assemble with little room left in the top of the caps. The result was a very sturdy structure. Materials were 10 Popsicle sticks, 2 caps and 5 pins. I am concerned about the pins splitting the sticks which would weaken the structure. When the vice was tightened it became hard to compress the pylon. With extra force the members cracked below the pins. There was little flexibility in this pylon as it was sturdy up until fracture. Page | 14
  15. 15. D. HEATHER - C2008809 DESIGN 2 The 3 sets of sticks were easy to assemble. The result was a sturdy structure which I was hoping the axial force could be centred between the 3 vertical pairs. Materials were 10 Popsicle sticks and 2 caps.When the vice was tightened it was hard to compress, then the structure began to fail with lesspressure needed. This was compressing the structure resulting in bowing of vertical members inan outwards direction. Continued winding of the vice resulted in fracture in middle of exposedvertical member. Page | 15
  16. 16. D. HEATHER - C2008809 DESIGN 3Attempted to construct a pylon design which utilised four vertical members. This made it difficultto add supporting members between verticals because of a lack of material. This was difficult toassemble as the four joint members had to be exactly a square to fit into cap. Materials used were10 Popsicle sticks and glue.When the vice was tightened it was hard to compress, then the structure began to fail with lesspressure needed. The structure continued to bow until failure in the middle of vertical member. Page | 16
  17. 17. D. HEATHER - C2008809 RESULTS AND CONCLUSIONS DESIGN 1 DESIGN 2 DESIGN 2INITIAL RESISTANCE 3mm 2mm 2mmFLEXABILITY 3mm-5mm 2mm-11mm 2mm-8mmCOMPRESION FRACTURE 5mm 11mm 8mmThese results allow me to work out the percentage distance each design allowed before fracture.Strain=compression length x 100 original length 1Design 15/120 x 100/1=4.16%Design 211/120 x 100/1= 9.16%Design 38/120 x 100/1=6.66%The construction of the 3 pylons in different configurations led me to believe Design 1 would bethe best. Design 2 and 3 were similar and I believed they would be less stable. The results weredesign 1 was the hardest to wind in, resisted more force, however, it had no flexibility andfractured quickly with no allowance to absorb the axial force. Designs 2 & 3 resisted at first thenallowed the vice to be wound in with less effort. This was absorbed by the members incompression which resulted in the members bending until failure. The design 3 four memberpylon bowed in and out where the 3 member pylon all members bowed out from the centre whichallowed more travel on the axial plane.In conclusion I can see a use for all types for different reasons. Design 1 could resist a greaterforce and Design 2 & 3 could absorb forces that could be calculated so the pylon would be elasticand return to original condition. Page | 17
  18. 18. D. HEATHER - C2008809 BIBLIOGRAPTHYRochford. J. (2011). Stage 6 Engineering Studies. [ed 2011]. Tumbi Umbi; KJS Publications. Page | 18

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