Study On Stability Performance Of Composite Beam Cable-stayed Bridge During Construction

The composite beam cable-stayed bridge is developed from the traditional cablestayed bridge.That uses the steel-concrete composite beam instead of the traditional concrete beam or steel beam,so that the materials can give full play to their advantages and increase the span ability of the cable-stayed bridge.The composite beam cable-stayed bridge has obvious advantages in the middle and long-span cable-stayed bridge,which is favored by the majority of engineers.At present,it has been widely used in the new cablestayed bridge.Based on a composite beam cable-stayed bridge with a main span of 310 m,this paper systematically studies the static performance and static stability performance of the structure in the whole construction process.The main work contents are as follows:(1)This paper introduces the development history of composite beam cable-stayed bridge,explains the first category and second stability theories of cable-stayed bridge,and discusses the factors affecting stability and the methods of evaluating stability.(2)Midas Civil finite element software is used to analyze the static performance of composite beam cable-stayed bridge during the whole construction process.The minimum bending energy method is used to determine the reasonable finished state of the bridge,and the stress-free state method is used to control the construction process.At the same time,because the bridge spans special structures,the construction period is required to be short and the influence is small.In order to minimize the construction steps,the cable adopts the once-tensioning method,which can be closed to reasonable finished state of the bridge in combination with the stress-free state method.(3)Midas civil finite element software is used to analyze the first category and second category of overall static stability performance of composite beam cable-stayed bridge in the whole construction process.And combined with the research results of stability performance of several important bridges,the change law of safety factor and buckling mode of the bridge are summarized.At the same time,the influence of ultimate bearing capacity is discussed by changing the parameters of important components of composite beam cable-stayed bridge.(4)The construction steps prone to lateral buckling of the main beam are found through the Midas Civil software,that is,the steps between the first tensioning of the cable to the formation of the wet-joint of the bridge deck.Abaqus finite element software is used to establish the solid element model of the most dangerous step,and the first category and second category of local static stability performance analysis were performed on the lateral buckling site.(5)Abaqus finite element software is used to establish the bar element model of the largest double cantilever stage and the largest single cantilever stage and the finished stage of the bridge,and the zero-beam is converted into solid element to form a full-bridge model with a mixed element,and the local static stability performance of zero-beam in three different construction stages is analyzed.At the same time,the short bracing stiffener at the joint of the tower and beam is studied,and a reasonable arrangement form with both safety and economy is proposed.