Research On New Type Of Concrete-filled Steel Tubular Continuous Rigid-frame Bridge

In recent 20 years, from the operating situation, concrete beams of the domestic-built PC continuous rigid frame bridge experience cracking problem at varying degrees. Although the factors caused box web cracking are complex, there are two unavoidable questions, i.e. box girder itself is too heavy and carrying capacity of the thin-walled box girder's webs is too small. Therefore, the author of this article, on the basis of the related documents which described a variety of concrete-filled steel tubular continuous rigid frame bridge, will compose a new type bridge with a concrete-filled steel tubular special truss structure. Such bridge can not only reduce the weight of itself, but also improve the carrying capacity, to effectively prevent the emergence of crack.This article will to carry out research about the five aspects as following:1,Carry out the related calculation and analysis to the Wanzhou Bridge and Hubei Xiangjiaba Bridge, the author will draw a conclusion: Main beam will use spacial four pyramid system which will bear the force equally and has a strong unity. The bracket truss structure design is more rational, has greater carrying capacity, and has greater application span. This concrete-filled steel tubular continuous rigid frame bridge can solve the problem that the PC continuous rigid frame bridge has too much self-weight, but its application of long-span is too small.2,Introduce the design features of the all-composite concrete-filled steel tubular continuous rigid frame bridge, it is estimated that such a bridge will fit for the span of 100 ~ 400m; Take Shaxigou Bridge as engineering background, test their innovative design, and mainly set the prestressed concrete-filled steel tubular steel frame on the L / 4 inter-and cross of the original continuous rigid frame bridge. Through the calculation, it shows that after the setting of skeleton, the maximum value of resistance limits of the bridge can be increased by 43.4 percent, deflection can be reduced by 55.4 percent. This bridge can solve the problem that the PC continuous rigid frame bridge web will crack and deflection is excessive, but it can not effectively reduce the box weight and can not solve the economically unreasonable problem.3,On the basis of the conclusion of the general truss,develop the single-truss into the multi-storey; Through qualitative calculation and comparative analysis at the difference of carrying capacity between the multi-storey truss and single-layer truss; and go on the comparative analysis at the difference of carrying capacity between the multi-storey truss and multi-layer arch truss, to sum up character of the multi-arch truss. Most rod parts of multi-arch truss under the stress and its weight can nearly reduce by 40%. Among the concrete and concrete-filled steel tubular structures which have the strong compressive capacity and weak tensile capacity, the multi-storey arch truss obviously has more advantages than parallel chord truss.4,Take Shuitu Jialingjiang Bridge as engineering background, try to design a new concrete-filled steel tubular space truss continuous rigid frame-bridge type, and calculate and check the truss internal forces of the main part. The analysis results of the test design showed that, compare with the original design, the weight of main beam is reduced by 50%, the security reserve of the main power bars is increased greatly, load-bearing capacity is improved and the cracking problem of the common Prestressed Continuous Steel Bridge web is avoided.5,try to design the truss nodes. 3 ~ 7 layer ball truss node will use high strength bolts, which will be featured with clear transmission and uniform force; 1,2 layer and parabolic layer node will use welding hollow spheres, which will be featured with large carrying capacity and high rigidity.