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BRIDGE BUILDING ASSIGNMENT 1.Work with a partner to construct 1 bridge. 2.Last Module Partner. 3.Draw a full size truss pattern from one of the six truss examples. 4.Construct the bridge using balsa wood. 5.Test the efficiency & applied force of the bridge.

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BRIDGE SPECIFICATIONS Work as a team to design and construct a balsa wood bridge. You may use no more than 7 - 24x1/8 balsa sticks. (14 ft. total) The bridge must have two identical trusses & a roadbed The bridge must be exactly 10 in length. The test block must fit between the two trusses. No excessive glue blobs. Support weight = Over 50 lbs. Tape may only be used to hold pieces while glue dries. Only two pieces of balsa wood may be laminated together.

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EXAMPLES OF TRUSS BRIDGES

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UNDERNEATH DECK TRUSS

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THROUGH TRUSS

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TRIANGULAR TRUSS

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K TRUSS

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WARREN TRUSS WITH VERTICAL SUPPORTS

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BALTIMORE TRUSS

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BALSA BRIDGE CONSTRUCTION Two trusses must be stand vertically. ____ pts. (20) No excessive glue blobs. ____ pts. (20) Tight joints. ____ pts. (20) Roadbed & top pieces do not over hang trusses. ____ pts. (20) Over 50 lbs. = 20 pts. 40 – 49 lbs. = 15 pts. Below 40 lbs. = 10 pts. ____ pts. (20) ____ pts. (100) BRIDGES GRADESHEET TRUSS VIEW DRAWING GRADE Lines are drawn with ruler. No wavy lines ____ pts. (20) Lines are 1/8 thick. ____ pts. (20) Drawing should have neat appearance. ____ pts. (20) Joints are clearly drawn. ____ pts. (20) Complete wood usage calculations. ____ pts. (20) ____ pts. (100)

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TRUSS BRIDGE The truss bridge... consists of an assembly of triangles. Truss bridges are commonly made from a series of straight, steel bars.steel

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WATER RIGHT ABUTMENTLEFT ABUTMENT SPAN ROADBED BRIDGE TERMS SUBSTRUCTURE BELOW ROADBED SUPERSTRUCTURE ABOVE ROADBED

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1 2 3 10 9 8 1 2 34 567 0 0 1 9 8 1 2 34 567 0 Warren Truss with Vertical Supports 1 2 3 10 9 8 1 2 34 567 0 Baltimore Truss 0 1 10 9 8 1 2 34 567 0 K Truss 1 2 3 10 9 8 1 2 34 567 0 Through Truss 0 1 10 9 8 1 2 34 567 0 Triangular Truss Underneath Deck Truss TRUSS EXAMPLES

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EXAMPLES OF JOINTS USED IN BALSA BRIDGE BUILDING

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WATER 3 2 1 0 1 9 8 0 1 23 4 5 6 7 10 GRADING PROCEDURE Lines are drawn with ruler (no wavy lines) Lines are 1/8 thick. Appearance of drawing (Easy to read) Complete wood usage calculations. Joints are clearly drawn. GRID SIZE =.25 DO NOT SHADE IN THE LINES! TRUSS VIEW Drawn by: __________________________________ Block #_____ Date: ____________

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WATER 3 2 1 0 1 9 8 0 1 23 4 5 6 7 10 GRADING PROCEDURE Lines are drawn with ruler (no wavy lines) Lines are 1/8 thick. Appearance of drawing (Easy to read) Complete wood usage calculations. Joints are clearly drawn. GRID SIZE =.25 DO NOT SHADE IN THE LINES! TRUSS VIEW Drawn by: __________________________________ Block #_____ Date: ____________ Bad joint Good joint

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WATER 3 2 1 0 1 9 8 0 1 23 4 5 6 7 10 GRADING PROCEDURE Lines are drawn with ruler (no wavy lines) Lines are 1/8 thick. Appearance of drawing (Easy to read) Complete wood usage calculations. Joints are clearly drawn. GRID SIZE =.25 TRUSS VIEW Drawn by: __________________________________ Block #_____ Date: ____________ 10 8.25 2.25 2.75 2 2 2 22 10 18.25 15.50 43.753.6 7.2

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