Influence of imperfections on the stability of beams with intermediate flexible supports

As expected, a decrease of the spring stiffness always leads to a reduced elastic critical buckling load. Nevertheless, when assuming geometric imperfections based on the 1st buckling mode, this may lead to a higher ultimate load than for the system with rigid intermediate supports, when identical imperfection amplitudes are used. These interesting results are presented and analyzed for two simple cases, in order to clearly show the main effects. These cases are: 1.) Columns under compression with additional flexible support at midspan; 2.) Beams under bending with additional flexible supports of the compressed flange only. For the latter case, a parametric study was performed, varying the number of intermediate supports and stiffness of the lateral supports.