Continuous Rigid Frame Bridge Construction Phase High Pier Stability Analysis

With the improvement of the calculation technique, development of the construction technique and employment of new material, the bridge structures gradually develop towards the long span and light weight aspects, the problem about stability increasingly represent prominent. Therefore, it is very necessary to conduct the comprehensive and systemic investigation on the bridge stability. The stability analysis of the long-span continous rigid frame bridge is different from the common analysis in the case that all kinds of loads are brought on the structure. The engineering properties of the different structure systems in different construction stages must be considered mostly in the analysis model, and so that the safety of the high pier of the long-span continous rigid frame bridge can be guaranteed by the emulation calculation of the most dangerous cases.In this paper, combined with a long-span continuous rigid frame bridge with thin-wall high piers—Du-Kou River Long-Span bridge which is a part of the Yichang-Wanzhou rail in Hubei province, the static stability is studied, including the following several aspects:(1) The eigenvalue stability analysis of the construction of Du-Kou River Long-Span bridge: This thesis uses the software ANSYS to build up the element analysis model with two types of elements: BEAM188 and SHELL131. This thesis carries out the eigenvalue stability analysis in the most dangerous cases. Further more, the stability of the construction stage can be evaluated.(2) The influence of the stability of high pier is analynized. Considering the important influence of temperature on high pier, the thermal-structure cumpled model is built to caculate the deflection of the 5^th pier under the lateral sunlight and the influence of the temperature on deflection is studied.(3) The nonlinear stability analysis of the construction Du-Kou River Long-Span bridge: take the deflection caused by the lateral sunlight as the initial deficiency, the nonlinear stability analysises of the pier construction and the largest cantilever construction stages are processed. The influence of the nonlinear on the structural stability is analynized.Such conclusions can be reached: the analysis results of the two types of models are nearly uniform. The first stability safety factors are greater than 4 required by the code ; based on the side-yielding rules, the bridge also has the second stability safety. The results of the two types of bucklings indicate that the largest cantilever construction stage is the most dangerous stage and the nonlinear stability analysis approaches the factual performance of the structure more nearly.