Program Development And Research On Key Technologys Of Long-span Skew Angle Incremental Launching Continuous Bridge

This paper is concern with new technologies of incremental launching and research on construction monitor and control about long span skew continuous beam bridges. It is a branch of western subjects which is leaded by the Ministry of Communications. Incremental launching method is popular in long span skew continuous beam bridges which are across canyons because constructing of freeways in the mountains of western China are limited by land feathers ,geological conditions and highway alignment .It's a meaningful work to develop programs of long span skew continuous beam bridges with incremental launching method for optimizing construction. Since only a few skew continuous beam bridges have been built buy this method. Standing on the background of Lishui bridge in Zhangjiajie, CASBD (construction analysis of skew beam bridges with incremental launching method) is programmed, by mean of inner force estimation, which combined FEM program with Visual c++. Depending on this CASBD, first the course of launching procedure is simulated and calculated and the parameter of the bridge is measured and analyzed in the course of launching. Second the effects of skewness on launching construction are investigated. Third forming analysis and optimum design of skew continuous beam bridges with incremental launching method are presented. Finally the key technologys of incremental launching have been studied. 1) Secondary internal force is analyzed in the course of launching procedure. Then the cause of aggregate errors of vertical angle and torsion angle,calculation of Secondary internal force and prophylactico-therapeutic measures are expatiated. 2) As the state of beam lowering is corresponding to the force distribution of beams directly, schemes of beam lowering are compared and optimized, which aim to reduce the moment of torsion after construction is finished. 3) Based on experience of design launching nose, design of detail structure on launching nose is optimized to reduce the maxim moment of beam and the maxim deflection of launching nose. 4) Location and method of installation of temporary pier are optimized in the course of launching.