Experimental Study On Bending Performance Of Mansard Steel Beam

With the development of economic construction, the new building structure emerges constantly. The concrete column and mansard steel beam composite architecture is more and more widely used in industrial plants. This structure can make full use high compressive strength, corrosion resistance and good fire of reinforced concrete columns and take advantages of flexural capacity, light weight of mansard steel beam. However, the existing building codes have no definite regulations on the design, application and characteristics of the new structural system, which make it difficult to design and construction for designers and so on. Therefore, the correct understanding the mechanical properties of the reinforced concrete column and mansard steel beam architecture is an important problem to be solved in the development of China’s construction. Research on reinforced concrete column-mansard steel beam structure system is in line with the national "low carbon, energy saving, environmental protection" philosophy, which has very important practical significance and strategic significance to the development of the industrialization of Chinese green building.This paper aims at the mechanical characteristics of concrete column-mansard steel beam structure. Firstly, the test model and program of mansard steel beam with both end hinges is independently studied and designed and static load tests on five groups of specimens with 1/12,1/10,1/8,1/6 and 1/5 slope were carried, the failure form was observed, the data was measured. Secondly, using the energy method and force method, theoretical analysis on mansard steel beams with both end hinges, which focus on support horizontal thrust, deflection with the changes of steel beam slope, span and loading position three factors in elastic range. At the same time, horizontal displacement of support was taken into consideration. Finally, establish the analysis model using the finite element software ANSYS Workbench and compare test data, theory and finite element simulation analysis results, and finally come to the following main conclusions:(1) The failure mode of mansard steel beam with both end hinges is bending member local instability failure and up flange local buckling damage at the apex point. The break point is the weak link; we can properly reinforce the up flange. The ultimate bearing capacity decreases with the decrease of the slope. The turning point is not ideally rigid, the initial stiffness of the breaking point is large, and stiffness decreases obviously after yielding.(2) The horizontal thrust of the bearing is a key problem in the analysis of the mechanical performance of the structural system, and the horizontal thrust is a liner function of the vertical load F, the function is HA=βF. The horizontal thrust of the bearing is very large, and under the condition of the test, it will be more than 3 times of the vertical concentration.(3) Release bearing displacement can greatly reduce the support reaction force, which can alleviate the problem of too large thrust to the lower support part of mansard steel beam. The middle span deflection is very sensitive to the relative displacement of the arch foot, especially to the small slope of the chevron steel beam, the bigger the vertical displacement of the arch crown caused by the smaller slope of the arch foot. The mid-span deflection is very sensitive to the release of bearing displacement, especially to the small slope of mansard steel beam. The smaller the slope is, the bigger the vertical displacement caused by bearing displacement of mansard steel beam is.