Cable prestress and alignment double control during construction of large-span cable-stayed bridges

Rational construction state,i.e.the cable prestress and structure alignment reach perfect condition simultaneously,should be defined,so that the cable-stayed bridge can reach rational state after the bridge construction.By use of the first order optimization calculation method,a nonlinear spatial finite element model for cable-stayed bridge construction control was developed with the bending strain energy of the bridge structure after construction and the alignment of the main girder taken as the objective functions and the initial tensile force of stayed cables and the prearranged height of main girder sections taken as the design variables.A case study was performed on a large-span cable-stayed prestressed concrete bridge,and the simulation of the pouring process of the cantilever of main concrete girders with the method shows that the method can effectively control the alignment of the main girders and the internal force of the bridge structure after the bridge construction,and thus it can efficiently determine the rational construction state of the cable-stayed bridge.