Deflection Stability of Beams Under Repeated Loads

Deflection stability problems of fixed-pinned beams under variable repeated moving load are treated both theoretically and experimentally. The results are compared with the ultimate load which causes the beams to fail by beam mechanism and with the shake-down load under variable repeated fixed point loading. Sixteen beams with span length of 39 in. (ten rectangular and six I beams) were tested under static and repeated loadings. Stabilized deflection due to the moving loading are usually larger than the values due to the fixed point loading for the rectangular beams, while for the I beams the stabilized deflection-load curves under the two loading conditions become close each other. The theoretical finding of the load-deflection behaviors is also confirmed by the test results.