Analysis Of The Mechanical Properties In Construction Process And Application Phase Of Steel-concrete Composite Cable-stayed Bridge

With the development of China's economy and the improvement of technology level,the application scope of cable-stayed bridge has been more and more extensive in recent years.The span has reached hundreds of meters or even thousands of meters.Among them,the steel-concrete composite cable-stayed bridge is more and more favored by the engineers by virtue of its superior force performance.The key to the design and construction of long span Steel-concrete composite cable-stayed bridge is the layout of cable force and the mechanical behavior of steel-concrete composite beams,which directly determines the operation performance of the whole structure of cable-stayed bridge.In this paper,Zhangshu City Ganjiang bridge cable-stayed bridge,systematically study the force performance of steel-concrete composite cable-stayed bridge.The main research contents are as follows:(1)Through the finite element analysis software Midas civil of bridge engineering,two finite element models of the whole bridge and the detail are established respectively.(2)By using the minimum bending energy method,the reasonable completion state of Ganjiang second Bridge is established,and the cable force in the construction stage is obtained by using the forward iteration method,which can be used to study the mechanical behavior of the cable-stayed bridge in the construction stage.(3)Based on the integral finite element model,the influence of time effect on the mechanical performance of a composite beam cable-stayed bridge is investigated.(4)The mechanical behavior of steel concrete composite beam and the influence of the shear stiffness of bolt on the mechanical behavior of the main beam are calculated and analyzed.Finally,the following conclusions are obtained:(1)For the cable-stayed bridge of Ganjiang No.2 Bridge,when the bending stiffness of the main tower and the main beam is reduced by 10~4,the rational cable force value of the completed bridge is more uniform and reasonable,which is the closest to the designed cable force;(2)During the construction stage,the axial force of the steel-concrete composite beam is mainly borne by the concrete,and the bending moment is mainly borne by the steel beam.the time effect has a significant influence on the internal force state of composite beam,Internal force redistribution will occur in the cross section of composite beam,with the shrinkage and creep of concrete,the internal force of concrete gradually decreases,and the internal force of steel girder increases gradually,the internal force of main beam gradually transfers from concrete to steel girder..(3)The age of concrete deck slab has a significant effect on the mechanical performance of the main girder of cable-stayed bridge.The shorter the age of prefabricated slab,the higher the redistribution degree of internal force of composite beam.The method of increasing the age of prefabricated board can be used to minimize the influence of concrete shrinkage and creep on the mechanical properties of the structure.(4)Under the action of vehicle load,the longitudinal and transverse stresses caused by two adjacent wheels are superimposed to a large extent,and the effect of adjacent wheels must be considered in the design and calculation,in addition,the shear stiffness of the bolt has a certain effect on the mechanical performance of composite beams.