Curved Steel Box Girder Special Shaped CFST Arch Bridge Model Test Study

Abstract:LTG Bridge is a large-span half-through curved steel box girder special shaped CFST arch bridge. The main beam is curved steel box girder with single-box eight-cell,and the curve radius is400m, set a diaphragm every2m. The main arch is in the vertical plane,filled with concrete. Auxiliary arch is in inclined plane, intersected into the main arch at the bridge deck.The main arch and auxiliary arch are connected integrally by transverse stiffened wing plates."V"shaped concrete inclined leg set in the arch spring.Four steel-concrete composite segments set at the junction of the inclined leg and the main beam. In this paper, the mechanical properties of the LTG bridge was studied systematically by the method of combining FEM analysis and model test. The major work is summarized as follows:1. On the basis of full-bridge spatial finite element analysis, analysis and summarized the force condition of beam and arch under various loads. Select11most unfavorable and representative conditions for the beam and arch as model test conditions.2. Comprehensive consideration of various factors, determine the model similarity ratio of1:7,and complete the model design.the special shaped arch and steel box girder were made in steel factory, the inclined legs were made and the concrete casting complete in the laboratory, Finally, beams, arches and inclined legs were assembled as a whole full-bridge model.3. Determine the loading scheme of each test condition and the loading value of every loading point.By building spatial finite element model of test model,the stress and displacement of test model were calculated and analyzed.Comparing the results with real bridge finite element calculation,ensure the displacement and stress of the test model is in good agreement with real bridge, which verified the feasibility of the loading scheme.4. Completed simulation test of11load conditions.The experimental results showed that:The experiment measuring of displacement and stress values are in good agreement with finite element analysis results,and the measured value is generally slightly less than the theoretical value. Load and strain have a good linear relationship,which means steel and concrete were in the linear elastic range.After completion of the11test conditions,the test model was still excellent without damage,which indicating that LTG Bridge have sufficient bearing capacity and great surplus.The research results of this thesis not only provide the basis for design of LTG Bridge, but also provide references for study of other similar special shaped bridge.