Homogeneous Structures Subjected To Repeated Structural System Changes

In this paper the creep effects in structures subjected to successive structural system changes are analyzed. The problem is related to structures that develop their structural system from statically determinate to indeterminate, with a gradual increase in the number of redundant restraints introduced at different times. Assuming a linear creep law, the stress redistribution caused by creep in the structure for each stage is evaluated. Writing the compatibility equation at the last restraint introduced, a recurrent formula for the history of redundant reaction is derived. The general solution is proposed as the sum of elastic quantities multiplied by integral terms (which take the creep effects into account) that are the same as the simple case where the additional restraints are introduced all together. The method presented demonstrates that, at all stages, the reaction at the last restraint does not depend on the introduction times of the previous restraints. This reaction is determined by a particular Volterra integral equation solved by numerical procedures of the general method.