Key Technology Research Of Long-span Steel Box Girder Cable-stayed Bridge With Single Cable Plane And Steel-concrete Composite Pylon

This article is based on the previous research results and the national design experience,taking Daxie Second Bridge as engineering background, using research methods consist offinite element analysis, real bridge test and section model test, doing a systematic study onlarge span single cable plane steel-concrete towers steel box girder cable-stayed bridge.Using the finite element method to get a reasonable construction cable force of DaxieSecond Bridge through several iterations, furtherly, through the calculation to constructionstage, the reasonable completed bridge status can be get. Doing the research to entirely stresssituation of Daxie Second Bridge under the situation of reasonable completed bridge statusand operation stage. The results indicate that the construction is safe and meet therequirements of relevant regulatory. Studying on the shear lag effect of cantilever side ofmid-span steel box under the maximum cantilever status by the finite element method, and theresults indicate that the shear lag effect at steel box girder webs inside and outside is the mostobvious.There is the characteristic that the stay cables do little contribution to resisting torque insingle cable plane cable-stayed bridge, so, to avoid the problem of the main beam’s torsiondeformation after stay cable tensioning construction stage, the steel box girder bottomreaction forces should distribute uniformly before the stay cable tensioning construction stage.Considering the example of high frame construction of Daxie Second Bridge, combining themethods of finite element analysis and real bridge test, the temporary reaction forces of thebracket steel box girder segments for high precision positioning and before and after weldingare monitored, based on the theoretical analysis results, reaction forces can be adjustedreasonably. Linear measurement result of steel box girder before mid-span closure indicatesthat steel box test point height difference of upstream and downstream is very small.For the problem that Daxie second Tower Bridge steel-concrete composite segmentstructure is complicated and the fundamental mechanism is not clear, conducting a test of areduced scale1:2segment model, stress and deformation of steel and concrete are testedunder the situation of prestressed load and designed the most unfavorable load, and the testeddata and the finite element simulation results are compared, The stress of steel, concrete,welding and transmission ratio at each part of binding segment can be get, The result indicatethat using the finite element method can simulate actual stress state of test model better. Thesteel-concrete composite section of pylon has a high safety reserves.Finite element simulation analysis method is used to research the sail-shaped tower wind resistance under static gust loads during construction, According to the conclusions,reasonable measures of wind resistance can be put forward, and taking studies on cable towerstatic gust response after taking measures to resist wind effect, The results indicate thatmaximum tensile stress of the tower and maximum lateral displacement in top of the towerare significantly reduced under transverse direction static gust loads after taking theappropriate measures.