Temperature Effect And Stability Analysis For High-pier And Multi-span Continuous Rigid-frame Bridges

There are many advantages of high-pier and multi-span continuous rigid-frame bridges, including large spanning abilities, strong integrity, good load-carrying capability and convenient for construction. The structural stability is as important as structural strength for such bridges. Due to the weak heat conduction of concrete, under temperature effect, internal forces, deformations and cracks may occur in the bridges.This paper mainly analyzed the stability and the temperature effect of Jing River Bridge. Finite element analysis was conducted to evaluate the time variations of temperature distributions and thermal stresses induced in Pier No.11 based on the early age temperature monitoring for concrete in the pier. According to the simulation results, thermal stresses that produced by heat of hydration during concrete pouring for segment No.0 of the main girder were predicted. Recommendations for reducing hydration heat were given.The annual and local temperature influence on Jing River Bridge was also carried out. Comparative analysis of stresses as well as deformations was conducted for the bridge under the change of annual temperature, gradients of local temperature in girders and piers. Results show that large displacements in the transverse direction of the bridge were produced by gradient temperature of the piers. The corrent design code for highway bridges, which not considering the gradient temperature of the pier, may result in unfavorable state for the structures. Especially for bridges with high-pier and long-spans.Regarding stability issues, emphasis was placed on the whole bridge structure, piers No.6 and No.7. Material nonlinearity and geometric nonlinearity were considered in Finite Element analysis. The results reveal that the wind and thermal load do not have too much effect on the stability of the structure. While dead load and live load have large effect on the stability of the bridge. The present study also indicates that when only geometric nonlinearity is included in analysis, the stability safety factors are about 64%-71% to that of the elastic stability safety factors. When both geometric nonlinearity and material nonlinearity are incorporated in analysis, the corresponding stability factors are about 27%-37%to that of the elastic stability safety factors. Accordingly, whether the bridge is stable or not can't be based on the result of the elastic stability analysis.