2011 Southeast Student Conference Balsa Bridge Competition

Transcription

1 2011 Southeast Student Conference Balsa Bridge Competition 1. Overview: The balsa wood bridge competition will challenge Civil Engineering students to balance various factors including, but not limited to cost, strength and weight in designing and constructing the best bridge within the set limitations. 2. Objective: Teams will design and build a model bridge from Balsa wood while minimizing production costs. 3. Eligibility: Teams will be comprised of no more than four undergraduate members. Each team should have a captain to present and test the bridge. 4. Logistics: Teams will submit a design paper by March 4, Bridges will be turned in to the judges one hour before testing begins. Adjustments can be made between submittal and testing of the bridge. The bridges will be tested on the Instron machine with load increasing until failure. Bridge costs will be analyzed, and the bridge with the lowest total cost wins. 5. Submittals: Teams must complete a design paper discussing their design process for the bridge prior to the competition. Bridges will be submitted at the time of competition. 6. Materials: 6.1. Only two materials are allowed for use on the bridge: Only.25 x.25 balsa wood members may be used One 1/8 inch balsa wood plate must be used as a bridge deck Only Standard Elmer s or carpentry/wood glues are allowed No further materials are allowed. 1

2 7. Execution: 7.1. All questions regarding interpretation of the rules will be referred to the event coordinator Teams are not allowed to solicit help from individuals not members of the team Design Paper: Paper must include the following: Name of College or University Team Captain s name and phone number List of members names and current status (Fr., So., Jr., Sr.) Balsa Information o Location of purchase o Quality purchased o Estimated material properties Adhesive Information o Brand purchased o Estimated material properties Maximum of 200 words on the design process CAD Drawing of bridge design Estimated weight of bridge and failure load Paper must not exceed four pages One electronic copy of the paper should be submitted to Dr. Guillermo Ramirez at gramirez@tntech.edu. Papers must be received by midnight (Central Standard Time) on Friday March 4, Late submissions will not be accepted. Submitters will receive an confirmation within 24 hours of paper submission Bridge Bridges should follow a basic truss design to be analyzed by the design team Bridges must include two trusses connected by horizontal members inches in total length inches in total width inches in total height inches clear span If included, bottom truss may not exceed 2 inches in height A balsa wood deck must be included for the bridge and cover the entire span of the bridge Deck must not exceed 1/8 inch in thickness Deck must include ½ inch hole at the center of the bridge for testing Deck may not be fastened in any way to the truss system of the bridge Glued surfaces must be <1/4 inch at connections No lamination or painting of bridges allowed Parallel members may not touch. There must be at least ¼ inch between parallel members There will be a 1/8 inch allowance in dimensions due to error in cutting. 2

3 A 2 inch by 2 inch block must be able to comfortably pass through the bridge with deck resting on the bridge A ½ inch diameter rod must be able to pass vertically through the center of the bridge for testing Testing Testing order will be determined by scores on the Design Paper, with the highest score being tested last The team captain will place the bridge on the scale and on the supports for testing. All other procedures will be carried out by the judges Each bridge will be tested by a 2 inch by 6 inch plate resting on the bridge deck. The plate will be attached to a rod in order to apply a uniform load across the bridge The bridge will be tested on the Instron machine. The load will be applied and continually increased until the bridge reaches its ultimate load. 8. Judging 8.1. Judging will be performed by a panel of professionals The decision of the judges is final Judging will be based on the scoring rubric and summation of the cost for the bridge. The team with the lowest final cost wins. 9. Scoring 9.1. Design Paper: The papers will be scored based on organization and preciseness of content. Deductions will be made for missing information. In the case of a tie, the paper with the highest estimated load-weight ratio will be tested last amongst the tied groups. Design Paper Scoring Rubric: College Name 5 Captain name and contact info 5 Team member list 5 Balsa information 15 Adhesive information 10 Design summary 20 CAD drawings 20 Estimated weight and load 10 Presentation 10 Total 100 3

4 9.2. Bridge Cost Analysis The following criteria will reduce bridge cost: Total bridge height <4 $5.00 per ½ inch Bridge design based on real bridge $10.00 Load taken $1.25 per pound The following criteria will increase cost: Total bridge height >4 $5.00 per ¼ inch Bridge weight $0.75 per gram Number of joints $1.50 per joint Inches of wood used $1.00 per inch Change in geometry of design $10.00 Change in weight of design $5.00 per 20 grams 9.3. Tiebreakers: Score on the design paper will be used as a tiebreaker Disqualification: Teams can be disqualified if they fail to meet all rules and eligibility requirements or upon the judges discretion. 4

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