Research On Section Optimization Design Of Continuous Steel-concrete Composite Beams In Highway Engineering

Steel-concrete composite beam bridge has the following advantages :high quality?accelerated construction ? light-weight ? save the number of template material ?environmental protection,etc.Because of the late start of the steel-concrete composite beam in China,the design experience is relatively scarce.In order to study the rational cross section structure of steel plate composite beams,this paper studies the two aspects of the model calculation and data induction.The main research work of this paper is as follows:1.Done a comparative study of elastic theory and elastoplastic theory of composite beams is made and the mechanical properties of steel-concrete composite beams are analyzed.In addition,the internal force analysis method of continuous and steelconcrete composite beam bridge is theoretically studied.2.The finite element model of two span continuous beam is established in ANSYS.The nonlinear ultimate failure state and slip effect of continuous composite beams are analyzed.The influence of slip effect and local buckling on ultimate bearing capacity of continuous composite beams is analyzed.3.Based on the fact that ANSYS can not automatically consider the shrinkage and creep effect of concrete,a simple method of uniform temperature load equivalent simulation is put forward,which has high accuracy.4.Considering the cross section characteristics of continuous composite beams in highway,The beam element model and space model based on the linear elastic theory are respectively established by using MIDAS civil and ANSYS finite element software respectively,Using the characteristics and advantages of two kinds of finite element software,the longitudinal and lateral of existing bridges are calculated respectively,and the force performance of the continuous composite beam is studied.Comparing the calculation results and considering the calculation efficiency and so on.The MIDAS beam element model based on the conversion section method is selected as the finite element model for the section optimization calculation.The stress of the steel beam under the basic combination of highway load is selected as the objective values of the section optimization.5.The influence of the change of the section size parameters on the target value described above is analyzed.The influencing factors including: thickNess of concrete bridge deck,thickNess of upper flange of steel beam,thickNess of bottom flange of steel beam,thickNess of steel beam web,and height of steel girder.With the requirements of the comprehensive cost and the standard limit,a comprehensive optimization method considering the size of each section and a feasible region for fast optimization are put forward.Some suggestions on the optimization of the current cross section are put forward.The results of the optimization analysis show that the method is effective and can be used as a reference for the designers.