An approximate analysis of the behaviour of laterally loaded, fully fixed beams and plates

An approximate method is developed for the elasto-plastic analysis of rotationally fixed and axially restrained rectangular beams and long plates subjected to lateral loading. The boundary conditions of the problem are satisfied exactly, but equilibrium is only satisfied at one point along the beam length. The load deflection behaviour can be determined by hand calculation. The behaviour of beams tested by others is analysed and the method is found to closely predict the behaviour observed experimentally. The effect of initial imperfection and axial movement at the beam ends is investigated. The possibility of beam instability is pointed out, and it is found that small movements at the beam ends can significantly affect its behaviour.