Optimization Of Multi-span Continuous Beam Closure Sequences Under The Different Construction Progress

Abstract:With the rapid development of transportation construction in our country, the multi-span continuous girder bridge has got great development. As the number of multiple span continuous beam bridges increases and the span gets increasingly bigger, more and more researches on closure have been conducted. Based on a multi span continuous girder bridge of hengyang Lei river and combining with the construction monitoring data, our paper is to analyze the closure and the main work and results are as follows:1. The author has referred to a lot of data about the closure sequence of multi span continuous beam bridge,has done much research on the development situation, construction characteristics and closure process of multi span continuous beam bridge,has compared the data from monitoring construction with theoretical data measured by MIDAS finite element software and has summarized the closure procedure of domestic multi span continuous girder bridges.2.Through using the large space finite element software MIDAS, this paper has analyzed seven kinds of construction closure sequence of six span continuous beam bridges, has compared the internal force, deflection and stress among all the schemes, and has gained better closure sequence of construction.3. The paper has analyzed the closure sequence of thefour span continuous beam bridge after middle-pier construction postpones,and meanwhile compared several aspects of four closure sequences, including internal force,deflection and stress, under the condition of the postponing. Combined with the analysis of internal force, deflection and stress,we can find that we should try to avoid the appearance of the age differences of adjacent cantilever sections during the actual construction process.When the actual construction conditions or other factors disable all the cantilever sections construction to be constructed at the same time, as for the research on four span continuous beam bridges in this paper, great efforts should be made to fold the side span before the construction of the middle-pier, which can not only improve the deflection of cantilever sections but also enhance the stability of the bridges and the force characteristics of bridges having been built4.For the paper’s research on the construction closure procedure of the four span continuous beam bridges, when it is unavoidable to delay the cannot the construction of middle-pier and the cantilever sections, we can fold side span first and then complete the closure of middle span after completing the construction of middle-pier and the cantilever sections. In this construction method, the deflection and stress of cantilever section on the right side of the side-pier is not superior to those of the side-span closure because of the closure of the side-span. The paper puts forward loading the concrete wet weight and hanging basket cantilever load to the section after the completion of side-span closure, and at this time, the deflection and stress of the construction phase will be improved obviously.