Abstract
The purpose of this study is to present the efficient analytical method including nonlinearity due to both change of geometry and material behavior for the elasto-plastic behaviors of space frames. In the previous paper, the generalized hardening hinge method including the difference of the strain-hardening factor in each of the generalized stress-directions was proposed. In this paper, the approximate yield surface equations of the steel section subjected to axial force and biaxial bending were proposed. Then, for the three-dimensional elastic member, the stiffness equation including the effects of change of geometry in incremental form is derived using the principle of virtural work and the Lagrangian formulation. The elasto-plastic behaviors of one story-one bay space frames subjected to the eccentric horizontal force or the noneccentric one are investigated by the present method. As a result, it obtained that these numerical results are in good agreement with experimental results and the behavior of space frames beyond the formuration of the collapse mechanism cannot be simulated by the plastic hinge method in which the strain-hardening is neglected.
