Construction Phase Limbs, Thin-walled High Pier Continuous Rigid Frame Bridge Stability Simulation Analysis

With the development of the long-span bridge structure,more and more high strength materials are put into application,bridge tower becomes tall of and the wall of the boxgirder becomes much thinner, global and local stiffness of the structure become down.Therefore, stability of the bridge is much concerned in recent years.In this paper, an engineering case-A Great Bridge is considered,the bridge is a long span continuous rigid frame bridge with thin-wall high-piers, built on XiaMen-ChengDun highway in HuNan province.The stability of the high-piers during the construction stage is analysed by using the current FEM software MIDAS/CIVIL,the main research are as follows:1,the paper summarizes the investigation development on stability of bridges with high-piers and some existing problems;discuss two kinds of basic theories of stability about bridge structure.By utilizing the current finite element program MIDAS/CIVIL,two types of finite element models,i.e.,beam model and plate model,are established for the dynamic characteristics and the linear stability analysis,obtained the linear stability safety factor value greater than the standard value at the largest cantilever construction stage,but the value is not biased conservative, is designed to limit reference value.2,According to General Code for Design of Highway Culverts, at the largest cantilever construction stage, the unilateral effects of High pier under the unilateral sunlight is carried out, obtained the maximum vertical displacement of the pier top (Pier deviation) and the maximum stress value.3,High pier unilateral deviation under sunshine as the initial defect,geometry,double nonlinear (geometric and material nonlinear coupling) stability analysis are carried out at the largest cantilever construction stage, obtained some greater impact factors for the bridge respectively are construction technology(hanging basket or normal construction), geometry and nonlinear material in the most unfavorable load case.In order to provide a theoretical basis for the preliminary design of the bridge,four types of the parameters,i.e.,unilateral sunshine, concrete strength grade, high-pier wall thickness,collar beam are analysised for the influence law of the stability of the high pier.4,By analyzing stability of the main bridge at the different stages, determinining the security reserve, obtained the overall stiffness, the stability and the ultimate bearing capacity of the high pier is the worst in the largest cantilever in the construction stage. The biggest part of cantilever construction is the key to control the instability in the bridge construction process.Some important parameters for the design of the thin-wall and high-pier bridge are obtained in these analyses, including ultimate load and stability safety factor of the condition in the construction stage.