GEOMETRIC NONLINEAR ANALYSIS OF LONG-SPAN COMPOSITE GIRDER CABLE-STAYED BRIDGE WITH THREE PYLONS DURING CONSTRUCTION STAGE

摘要

At present,some studies on the geometry nonlinear of the large span cable-stayed bridge during construction stage have been done at home and abroad,according to three geometric nonlinear factors (stay-cables sag effect,beam-column effect and big displacement effect),the researchers always use the method advanced by Fleming JF in 1979.However,with the increase of the span,the precision of this method decreases.This paper takes Wuhan Erqi Yangzi River Bridge as the background of research.Using elastic catenary cable element to analyze stay cable sag effect,geometric stiffness matrix to analyze beam-column effect,CR formulation incremental method to analyze large displacement effect,the space structure nonlinear finite element model is established to research the regularity effect of the three geometric nonlinear factors on the deformation and internal force of the long span composited girder cable-stayed bridge with three pylons during cantilever construction stage.The results show that:the analysis method adopted by this paper has a high precision:the nonlinear effect on the deformation and stress of the girder beam increases as the cantilever length increases,and reach the maximum in the single cantilever and double cantilever state; stay cable sag effect plays a leading role in the three geometry nonlinear factors.The paper provides important basis and guarantee for the rationality on cantilever construction of composited girder cable-stayed bridge.