Local Stress Study For Arch Springing Of Large Span Continuous Beam-arch Composite Bridge

Arch springing is the key part of continuous beam arch composite bridge, the mechanicalperformance of it has a very big effect on the bearing and spanning ability of the bridge. Archrib, collar beam, support, cross beam all are in this intersection,and the strengthening of localcomponents are also many, so it makes the arch springing, complex. So it is necessary toanalysis beam-arch-binding site in details.In the long-span beam arch combination bridge,analysis of the whole of bridge usually adopts the theory of truss structure, but it can notsimulate the details of construction, and the calculation precision is low.And it can not reflectthe regularity of stress distribution in binding site. This article uses the finite element softwareMidas Civil to do the analysis of the whole of bridge, and uses detail finite element softwareMidas FEA to analyse the mechanical properties of arch springing.At the last, the main workand conclusions of the research are as follows:(1)Firstly,introduced the basic performance, structural form and the main advantages ofthe continuous beam arch composite bridge in details, and summarized the beam-arch-bindingsite on the present studying situation of the domestic and foreign research and the existingproblems, and clarified the importance of the research object in this paper.(2)On the background of a combination of a continuous beam arch compositebridge,considering the construction phase of the whole bridge under the condition of theoverall mechanics analysis, and in the most unfavorable typical load conditions to extract thecapture the stress and bending moment of the cross section, and compared with theconstruction monitoring data.The comparison results show that the construction adjusted tothe design requirements, the beam’s stresses are in a safe range.(3)Loaded the stress and bending moment of the whole bridge analyiss into the localrelevant section model,according to the saint venant principle of equivalence, and simulatedboundary conditions according to the actual supporting. Then, on the most unfavorable typicalload conditions,completed the local stress analysis of beam-arch-binding site (including theconsideration of creep and shrinkage of concrete and the loss of prestress),and summarizedthe related distribution law. Conclusions indicated that in the the number of the girder zero,arch support, Most of concrete in the steel pipe, stress distribution was uniform, and satisfiedthe requirement of strength design. When designing the arch feet should take the effect oflateral wind load into account. General the structure of the arch springing site was reasonable,mechanically safe. Due to the ferrule effect, the stress of most concrete in the steel tube isuniform on longitudinal compression. Only in tectonic salient structure, prestressed anchoragezone, bearing, the junction of the arch rib and abutment,the junction of arch foot and arch rib, arched girder consolidation area there are certain degree of stress concentration, appropriatlset ease transition section or reinforced reinforcement layout.(4)Discussed the possibility of other finite element methods, put forward three kinds ofwhole bridge model (I~III) and four kinds of local models (I~IV), and have done modelanalysis. And then compared with the measured values, finally summed up the pros and consof the all methods, and puted forward relevant suggestions. Suggestions for beam-arch-binding site study were that it should use the analysis method II used in this article, simulatedthe steel tube and concrete respectively,and considered the material nonlinearity and thebond-slip between steel tube and concrete. Considering bond-slip between steel tube andconcrete,and under the condition of joining interface contact element, the nonlinear analysisresult of the double material model has higher safety and precision than the double elasticmodel without considering bond-slip. And stress redistribution happens on part of the coreconcrete.Research results and the recommendations of this article could provide certain referencebasis for the beam arch combination bridge design and construction.