Research And Analysis On Mechanical Properties Of Partially Embedded Steel-concrete Composite Beams

Steel-concrete composite structure has a series of advantages,so it has been widely used in all kinds of buildings and bridge structures.In this thesis,a partially embedded steel-concrete composite beam is proposed in engineering practice,the new communication composite beams of steel and concrete composite beams and steel reinforced concrete beam,has the excellency of reducing the height of architectural structure,improve the overall stability,make full use of the thick plate girder strength and increase the advantages of steel and concrete work,has a broad application prospect.In this thesis,the flexural performance,stiffness and deformation of the normal section of some embedded steel-concrete composite beams are studied and analyzed in detail.The main work contents are as follows:1.Establish the finite element model of partially embedded steel-concrete composite beam,and analyze the stress,deformation and failure characteristics of the whole process from loading to failure.At the initial stage of loading,the yield height of the section steel is small,which is mainly the tensile yield of some webs at the mid span and support,and the maximum principal stress of the concrete at the interface between the concrete slab and the section steel reaches its tensile strength.With the increase of load grade,the yield height of section steel increases gradually,the lower flange and most webs of section steel yield in tension,and the maximum principal stress at the top and edge of concrete slab reaches its tensile strength one after another.The analysis shows that the failure characteristics of partially embedded steel-concrete composite beams are similar to those of steel-concrete composite beams,both of which are bending failure.The failure feature is that the lower flange and part of the web of the section steel yield in tension,and the compressed edge fiber of the concrete is crushed.2.The effects of important parameters such as embedded depth,strength grade of section steel,strength grade of concrete and reinforcement ratio of slab on the mechanical performance of partially embedded steel-concrete composite beams are analyzed.The results show that with the increase of embedded depth,the clear height of composite beams decreases,and the bearing capacity under the same section decreases,but the reduction range is small;Increasing the strength grade of section steel,the strength grade of concrete and the reinforcement ratio can significantly improve the bearing capacity,and the influence of the strength grade of section steel is more significant.3.Based on reasonable assumptions and finite element analysis model,the calculation formula of flexural capacity of partially embedded steel-concrete composite beams is proposed,and the calculation results are close to the finite element analysis results.Through the analysis and research of the existing stiffness calculation methods of composite beams,the stiffness and deformation calculation methods suitable for partially embedded steel-concrete composite beams are established.