NONLINEAR STABILITY ANALYSIS OF LONG-SPAN CONTINUOUS RIGID FRAME BRIDGE WITH THIN-WALL HIGH PIERS

By utilizing the finite element program ANSYS,two types of finite element models,i.e.,beam model and shell model,are established for the nonlinear stability analysis of Long Tan He Great Bridge,a practical rigid frame bridge.In these analyses,geometrical and material nonlinearity are simultaneously taken into consideration.For geometrical nonlinearity,Updated Lagrangian formulations are adopted to derive the tangent stiffness matrix.In order to simulate the nonlinear behavior of plastic hinge of the piers,the multi-curves element COMBIN39 with the Multi-spring model and the bilinear rotational spring element COMBIN40 are used in shell model and beam model,respectively.Numerical calculations show that satisfactory results can be achieved in the stability analysis of the bridge when the double coupling nonlinearity effects are considered.This conclusion is significant for the practical engineering.