The Study On The Construction Control Of The CFST Arch Bridge With Prestressing Roof Beam

In our country, concrete-filled steel tubular arch bridges have become a new technology of the development of the construction of bridges in recent years. It has the merits of light deadweight, great intension, strong capacity of counter-distortion. It can preferably resolve some contradictions such as the materials for constructing bridge are save, fixing weight is light, the construction is simple, with great bearing capacity. It is a kind of more ideal structure form of long-span arch bridges.In other countries the researches and applications about concrete-filled steel tubular structure have been taken about one hundred years. But in our country the researches have been taken since 1950s. Since 1990s, concrete-filled steel tube, as a new-style combined material, for its mechanical capability was very fit for arch systematic bridges, got broad application and swift development.The text, with the project instance of Qingxi river bridge in Xiangfan, takes researches on the control of the construction craft of CFST arch bridge. It has opened up the organized new-type structure that the steel tube concrete to join with the prestressing force roof beam, meanwhile, the structure form in the concrete-filled steel tubalar arch bridge has result of casting a brick to attract jade.The text is the study on the construction craft course (process) of the CFST arch bridge with prestressing roof beam, on the basis of calculating in theory, has carried on proper adjustment to the original construction process. Because Qingxi river bridge adopts constructing with brackets, how to set up the brackets; the calculatation and analyse of the intensity, rigidity and stability of the structure have been done..In order to get a good line when the bridge is built up we set up the structure-producing and fixing pre-arch of the steel tubular arch. During the element calculating of the pre-arch, we adopt 3 kinds of simulation methods to combining structure of the steel tube and concrete. Trough comparative analysis, the method that regarding the steel tube and the concrete as two elements, which have the same nodes, can simulate the constructing process better. By calculating, the steel tubulararch and the roof beam have the same pre-arch. The deflection observed in the course of construction, indicate that the fixing pre-arches of the steel tubular arch and the roof beam are reasonable, which supervises the construction effectively.Trough theorical calculation, we can get that choosing to remove the brackets before pouring the concretes in the steel tubular arch is reasonable, which will really reflect the advantage of this kind of combining structure (material) of steel tube, concrete.When to draw the prestressing cables and the quality of it, that is crucial to the construction of CFST arch bridge with prestressing roof beam. According to analysis, drawing partial prestressing cables afer pouring the concretes in chord tube, but before pouring the concretes in the joining panel, is reasonable.The calculation and analyse shows that the order of drawing the prestressing cables has little effect on the line, so has the stress of concretes in the arch and the roof beam. But it has certain effect on the stress distribution of steel roof beam and steel tube.The paper has also carried on stress testing and line measurement while the construction craft is controlled. Testing results indicate, the construction craft adjusted is feasible, the stress and the deformation of each control sections accord with the calculating results better.