Research On Performance Of Expansive Concrete In Steel-pipe Arch Bridge

The most crucial issue in Long-span concrete-filled steel tubular arch bridge is how to ensure steel and concrete effective recombination and to make steel and concrete cooperative work. Therefore, finding out the effective composite expansion ratio and determining the reasonable expansive capacity of concrete-filled steel tubular are the key factors of the construction quality with Long-span concrete-filled steel tubular arch bridge.According to Gansu Provincial Communications Department research project" the Experimental study on the slight expansion of concrete-filled steel tube with the G213-ray the Qijia Yellow River Bridge",through the method of test and theoretical analysis, the main contents of research and analysis are as following:(1) According to engineering practice and theoretical analysis, the limited expansion ratio of concrete with the Qijia Yellow River Bridge should be controlled in (1.6～4.2)×10^-4. From the results of experiment, we can get that, the steel tube and the concrete can work best when the effective expansion rate is about 3.5×10^-4.(2) Optimizing the concrete mix, the mix proportion of high-performance expansion concrete can be compounded. This concrete has good properties, high flow, low slump loss and low hydration heat, which can meet the construction and quality requirements of the Qijia Yellow River Bridge.(3) Fly ash and expansive agent "double-doped" can influence the expansion and intensity performance of concrete. The results show that: in the "Double-doped" concrete, fly ash can promote the expansion of concrete. In the project, the optimum mix amount of fly ash should be controlled in 15%.(4) The effects of concrete expansive properties with expansive agent mixing amount at the same water-binder ratio was researched, and the change trend of expansion ratio was analyzed. The results show that: the optimum mix amount of expansive agent is 12% in the project.(5) The relationship of self-stress and expansive agent mixing about the high-strength and expansive steel tube concrete was researched; using the finite element method, the expansion property of core concrete was simulation analyzed, the finite element analysis results and the testing results are basically consistent.