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A prestressed concrete beam used over a span of 6m is 100mm wide and 300mm deep, live load of 4kn/m, density of concrete is 24kn/m3, modulus of elasticity of concrete is 36 and steel is 210kn/mm2. Find rotation due to loads(sagging moment)?

A prestressed concrete beam used over a span of 6m is 100mm wide and 300mm deep, live load of 4kn/m, density of concrete is 24kn/m3, modulus of elasticity of concrete is 36 and steel is 210kn/mm2. Find rotation due to loads(sagging moment)? Correct Answer 0.0045

E = 210kn/mm2, Self weight of the beam, g = (0.1×0.3×24) = 0.72kn/m Live load on the beam (q) = 4kn/m, Total load on the beam, Wd = (q+g) = (4+0.72) = 0.00472kn/mm Rotation due to prestressing force θp = PeL/24EI = (100×50×6×103/24×36×210×106) Sagging moment = 0.00525radians.

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