Hello_World2
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How would I find the maximum load that can be placed at C just before the bridge starts to lift? Thnaks !
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Uniform Distributed Loads on a beam (1 Viewer)
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wizzkids
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Essentially, use the Sum of the Turning Moments = 0 for static equilibrium. Choose the obvious turning point, which is "B". Also note that when the beam starts to lift, the reaction at support A will be zero.
First Step. Identify the forces. 20 metres of u.d.l. on the l.h.s. of the fulcrum, 4 metres of u.d.l. and the point load X on the r.h.s. Using Newton's Principle of Centre of Effort, replace 20 metres x 2 kN/m = 40 kN with a point load of 40 kN located at 10 metres to the left of B (why at 10 metres to the left of B? think about it!) Replace the 4 metres x 2kN/m with a point load of 8kN located 2 metres to the right of point B.
Second Step. Sum the turning moments about B. (- 40 kN x 10 m) + (8kN x 2m) + (X x 4m) = 0 and solve for X.
Notice that I have adopted the sign convention that anticlockwise turning moments are negative, and clockwise turning moments are positive.
First Step. Identify the forces. 20 metres of u.d.l. on the l.h.s. of the fulcrum, 4 metres of u.d.l. and the point load X on the r.h.s. Using Newton's Principle of Centre of Effort, replace 20 metres x 2 kN/m = 40 kN with a point load of 40 kN located at 10 metres to the left of B (why at 10 metres to the left of B? think about it!) Replace the 4 metres x 2kN/m with a point load of 8kN located 2 metres to the right of point B.
Second Step. Sum the turning moments about B. (- 40 kN x 10 m) + (8kN x 2m) + (X x 4m) = 0 and solve for X.
Notice that I have adopted the sign convention that anticlockwise turning moments are negative, and clockwise turning moments are positive.
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