Research On The Mechanical Properties Of Lightweight Steel Die Net And Modified Expanded Polystyrene Granule Concrete Composite Wall

The structure of lightweight steel die net and modified expanded polystyrene granule concrete is a new type structure system,which takes cold-formed thin-wall lightweight steel,steel die net and modified expanded polystyrene granule concrete as the main materials,and relies on the light steel die net frame which is built rapidly,and combines the lightweight steel prefabrication and assembly with the light concrete cast-in-place.Compared with the traditional structure system,the structure system realizes the industrialization of building structure system,and achieves the goal of green development of building industry.However,there are few researches on this new structure system at home and abroad.In this paper,based on ABAQUS finite element software,the numerical model of lightweight steel die net and modified expanded polystyrene granule concrete concrete composite wall is established,and the compression performance and seismic performance of the composite wall are studied.The failure mode and ultimate bearing capacity of composite wall under vertical load and eccentric load are analyzed;the failure form,skeleton curve,ductility,energy dissipation capacity and stiffness degradation of composite wall under low cycle reciprocating load are analyzed.The influence of the parameters such as steel die netstrength,modified expanded polystyrene granule concrete strength and horizontal steel brace on the compression performance and seismic performance of the composite wall is analyzed.The main research results are as follows:1.In the lightweight steel die net and modified expanded polystyrene granule concrete composite wall,the existence of steel die net can improve the vertical bearing capacity of the composite wall by 6%,the horizontal bearing capacity by 9.31%,and the ductility of the composite wall.Under the action of low cycle repeated load,the steel die net can bear part of the tensile stress,effectively restrain the crack development of the modified expanded polystyrene granule concrete,and change the stress mode of the composite wall.The increase of steel die net strength has little effect on the bearing capacity of composite wall,but can improve the ductility of wall.2.Modified expanded polystyrene granule concrete can greatly increase the vertical bearing capacity,horizontal bearing capacity and initial stiffness of the composite wall,but the ductility of the composite wall will obviously decrease.Considering the influence of many factors,it is suggested that the lightweight steel with 30%opening rate should be selected as the load-bearing component of the composite wall.3.The horizontal steel brace has a great influence on the seismic performance of the composite wall,and the horizontal bearing capacity of one horizontal steel brace arranged in the composite wall can be increased by 20%.The horizontal bearing capacity of two horizontal steel braces arranged on the composite wall can be increased by 32%.The horizontal steel brace can make more vertical lightweight steel and steel die net participate in the overall stress of the structure,so as to improve the horizontal bearing capacity of the composite wall.But too many horizontal steel braces will affect the ductility of composite wall.4.Lightweight steel,steel die net and modified expanded polystyrene granule concrete can work well together and give full play to the material characteristics.The failure mode of composite wall under axial load and horizontal reciprocating load is similar to that of frame infilled wall.Under eccentric load,the failure mode of composite wall is similar to that of ordinary concrete members.In engineering practice and laboratory tests,the seismic performance of composite walls can be improved by using high-strength steel mesh and reasonably arranging horizontal steel braces.