Residual Displacement Analysis of Structures at Shakedown

摘要

The residual displacements developing in the shakedown process of an ideally elastic-plastic beam system under variable repeated loads vary non-monotonically. Therefore, it is important to determine the variation bounds. In this paper, the numerical methods, as well as the ex-tremum energy principles, small displacement assumption and mathematical programming theory are used to develop the mathematical models of the analysis problem. By solving the analysis problem, where the load locus is progressively expanded, it is possible to determine the upper and the lower bounds of the residual displacements. It is assumed that non-monotonically varying residual displacements do not exceed these bounds. The application of the proposed load locus expansion method is illustrated by a case study of a multisupported beam. The results obtained in this investigation show that, at given repeated variable load, a structure can adapt to the changed conditions, but the values of the residual displacements may differ. Using the proposed method, it is possible to determine the bounds of residual displacements without analysing the history of the loading.