OPTIMIZATION METHOD TO DETERMINE TENSIONING FORCE DURING CONSTRUCTION OF CABLE-STAYED BRIDGES

摘要

Cable-stayed bridges are high-order statically indeterminate structures and the structure continuous changing during construction. It is difficult to determine initial and subsequent tensile force of cables in construction period. A method is presented to calculate the initial and subsequent tensile force of cablestayed bridge and each cable is only tensioned twice in construction. In cantilever construction period each cable is tensioned only once. The tensile forces are determined by the principle that during construction and after completion, the stress state of the bridge should meet the force requirements and the tower and girder should basically maintain a straight line. After the bridge is closed, the final target cable forces are determined with the principle of smooth line, reasonable stress state, regular distribution and small difference of cable forces in the bridge. Then the final tensile forces under given tensioning sequence are determined by iterative computation. In construction practice the final cable forces can be obtained only after one-round tension following the final cable forces. This method has been applied in the design of one large railway cable-stayed bridge and a good effect has been obtained.