Nonlinear analysis of spatial framed structures by a lumped plasticity model based on the Haar–Kàrmàn principle

摘要

A lumped plasticity model is proposed for the nonlinear static and dynamic analyses of three-dimensional reinforced concrete (r.c.) frames. A bilinear moment-curvature law and an interaction surface axial force-biaxial bending moment are considered. The nonlinear dynamic analysis is performed using a two-parameter implicit integration scheme and an initial-stress like iterative strategy, adopting the Haar–Kàrmàn principle. As a preliminary, two cantilever steel beams, one with box-section and one with tubular section, are used for validating the proposed model under monotonic and cyclic loadings. Moreover single-storey r.c. three-dimensional frames, with square and rectangular cross-sections, subjected to bi-directional ground motions, are assumed as test structures for studying the sensitivity of the model to changes in strength and stiffness input parameters. Comparisons with more refined fibre models prove the reliability of the proposed model.