Stability Analysis Of Continuous Rigid Frame Bridges With Double-leg Thin-walled High Piers During Cantilever Erection

The continuous rigid frame bridge with double-leg thin-walled high piers is commonly built in China, because of its advantages on economy and construction. However, the problem of stability in cantilever construction stage is very remarkable for the bridges with high piers. Based on the Longtanhe Bridge of Hurong national highway in the west of Hubei province, this thesis focuses on the stability of the continuous rigid bridge with high Piers during the construction of cantilever. The main research work is summarized as follows:(1) First, the existing research work on the stability of high piers had been introduced. Then, the solution methods of the first type stability and the second type stability were summarized in this thesis and the main difference between them was discussed.(2) Based on energy principle, the whole stability during the construction of double-leg thin-walled high Piers was studied. According to the geometric conditions between piers and coupling beams, the determining method of static stability coefficient of such structures was given, and the simplified formula of in-plane and out-plane stability coefficient during the construction of cantilever was deduced. It indicates that the results obtained by the proposed method in this thesis agree well with those obtained by finite element method. But the proposed method is obviously much simpler and more practical.(3) Based on the proposed method, the effect of axial deformation of piers and different geometric parameters on the stability coefficient of high piers was analyzed. It turns out to be that the slenderness ratio (λ), the spread ratio of pier height and pier limb (l/l_b) and the stiffness ratio of girder and pier(EI_b/EI₀) have great effect on the stability coefficient. For the high pier structure with coupling beams, the axial deformation of piers has remarkable effect on the stability coefficient of high piers, so it is necessary to consider the effect of axial deformation of piers when analyzing the stability of high piers.(4) Taking Longtanhe Bridge of west HuRong national highway for example, based on the finite element procedure, which was programmed by APDL language, the in-plane, out-plane and spatial stability of high piers in all kinds of cantilever construction was studied, which considered both geometrical and material...