Question 1 Report
A student is studying different types of bridge structures for a design project. The project requires the student to design a model bridge that will span a gap of 500mm using card and balsa wood.
(a) Name and sketch two different types of bridge structure. [2]
(b) State the difference between a frame structure and a shell structure. [1]
(a) Two types of bridge structure, named and sketched: [2]
1. Beam bridge:
A beam bridge is the simplest type: a flat deck (beam) supported at each end on piers or abutments. The deck resists bending under the loads placed on it.
2. Truss bridge:
A truss bridge uses a triangulated framework of members (top chord, bottom chord, verticals and diagonals) to distribute loads efficiently. The diagonal members create rigid triangles, making the structure lightweight yet strong.
(b) Difference between a frame structure and a shell structure: [1]
A frame structure is made from separate members (bars, tubes, struts) joined together to form a skeleton framework. The strength comes from the arrangement and connections of the individual members. A shell structure uses a continuous outer surface or skin to enclose space and carry loads. The surface itself provides the structural strength rather than internal members. Examples: a bicycle frame (frame structure) versus an egg or aircraft fuselage (shell structure).
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