2Physics of Bridge Building Three basic typesSpan: simplest form – beam supported on vertical supports. Also truss bridge, cantilever bridgeArch: compression forces push outwards horizontally against the supportsSuspension: main cables anchored to towers, suspender cables support roadway. Cables are in tension.
3A bridge in New South Wales, Australia example of truss system (rigid triangular framework)
12Some Physics Considerations Choice of materialStrength:in tension, compression, bending, torsionShape of framework(why triangular?)Testing the design – use of modelsPhysical scale modelsComputer models
19The Bridge Competition You are a team of bridge designers working for the internationally known bridge building company ………………………………………….(choose a name for your company)Your task is to design and build a single span bridge to the specifications given on the sheet, using the materials provided.The bridges will be judged on three categoriesTechnical MeritArtistic ImpressionWeight
20Bridge specifications Bridge has to span a gorge 90 cm wide, with sides at the same height.The centre point of the underside of the bridge must be at least 10 cm higher than ground level.The bridge has to carry a continuous single track car deck ( made from card provided), allowing a model car to travel safely across the gorge.The car deck can have a maximum incline of 30 degrees at any point.The bridge should be sufficiently rigid that the span bends less than 2 cm if CAN! stops at centre.
21Technical specifications Single-track car deck (made from card)Coke can (full)Makes bridge bend by less than 2cm at the centre<30°>10cm>90cm