The Second Order Elastic-Plastic Analysis of Plane Steel Frame Structures with Semi-rigid Connections

Considering the nonlinear behaviors of semi-rigid connections, a new calculation model for the second order elastic-plastic analysis of plane steel structures is presented by replacing the general element with a new one, which has two rotational springs at its ends. Based on the theory of beam-to-column, the element's rotation-displacement equations are revised, and the second order elastic-plastic rigidity matrix of this kind of structure is derived in this paper. And the second order elastic-plastic program of this kind of structure is worked out. Two steel frames are calculated with this program. The results of calculations show that this model is reliable and fit to the analysis of all plane steel structures.