Micro Expansion Concrete-filled Steel Tube To Long-span Arch Bridge Test Research

Being provided with excellent mechanical properties and the good economic efficiency, steel tube concrete is paid more and more attention, developed and utilized preferentially by all countries' civil engineering . More and More concrete-filled steel tube arch bridge are taken into use because of its long span, wide deck, light weight, high strength, model aesthetics. But the quality of concrete in the steel tube considerably affects the security of the engineering structure, it may cause quality incidents or defects, such as internal air, concrete imperfect filled , overlarge contraction gap between concrete and steel pipe , which drop structure bearing capacity. Therefore, the mixing content of new mix concrete should have been required in big slump, good workability, water-tightness, well pumpability and long slow setting time etc. The hardened concrete should have excellent characteristics in high self-compactness, tiny shrinkage and high initial strength, which cause difficulties in the design of mix proportion of the micro expansion steel-tube concrete. And the concrete is invisible after being poured into steel tube, , which brings inconvenience for testing the concrete strength of the structure and other physical properties. Meanwhile, it is a fairly complex problem to make sure whether concrete and steel pipe can be collaborative working. Based on the practical project, the following test and research are focused on in the four chapters of this text:(1) The influence of raw material on micro expansion concrete is discussed, and raw materials used to configure micro expansion concrete were chosen scientifically.(2) The benchmark ratio of C55 micro expansive concrete is designed with the orthogonal experiment method(3) Basing on benchmarks, the expansion rate of micro expansive concrete is determined and analyzed by adopting different proportion of the admixture expansive agent.(4) Steel and PVC tube of different diameter sizes are pored using the selected concrete of the specific expansion agent admixture thing regarding mix-proportion by the test and analysis, and component test and analysis are carried out. And a conclusion is drawn(5). Using MADIS analysis software for modeling and simulation included the computation.(6) The steel tube and concrete stresses of the actual project is test on site and studied by means of wireless testing systems combined with the pre- installed inner concrete strain meter and surface strain gage. The cooperative work performance between steel tube and concrete is carried out being combined with the result of finite element simulation calculation by MADIS analysis software conclusively.