| High strength lightweight aggregate concrete is an excellent green building material,which has the advantages of light weight,high strength and good durability.Compared with the normal weight concrete,the ductility of light aggregate concrete column is lower,it could not meet the design demands.The compressive strength and ductility of concrete column can be improved by cross-shaped steel.However,there is few research on light weight aggregate concrete column with cross-shaped steel,and the specimens with H-shaped steel.Therefore,it is necessary to research the axial compression behavior of lightweight aggregate concrete column with cross-shaped steel.This paper has carried out finite element analysis and theoretical analysis on the axial compression behavior of cross-shaped steel-high strength lightweight aggregate concrete composite column.The work was showed below:(1)The test of axial compression behavior of cross-shaped steel-high strength lightweight aggregate concrete composite column was completed,the strength of concrete,steel ratio,reinforcement ratio,stirrup ratio and steel form were main variables,the failure mode were investigated.Results show that the concrete strength has the most obvious influence on the ultimate bearing capacity of the column,and the ultimate bearing capacity of the specimens with LC60 is 34 percent higher than that with LC40.The columns with more stirrup and steel may lead to a higher ultimate bearing capacity,and reduce the shear crack.The ultimate bearing capacity of specimens with diagonal cross-section steel is slightly lower than that of specimens with orthogonal cross-shaped steel,but the deformation capacity is better.(2)The finite element simulation was carried out.Nonlinear numerical simulatiom of cross-shaped steel-high strength lightweight aggregate concrete composite column under monotonic loading are developed with ABAQUS.The model parameter is reasonable and the accuracy is good,and it can rationally simulate the axial compression process of the lightweight aggregate concrete column with cross-shaped steel.On this basis,Parametric study was carried out,and the mechanical performance of the column was further analyzed and studied.It is more effective to reduce the spacing of stirrups than to increase the diameter of stirrups.The confined concrete area of lightweight aggregate concrete columns with diagonal cross-shaped steel is larger,and the peak stress of core concrete increases by 2%.(3)The mechanical mechanism was carried out.According to the strength of the stirrup and steel constraint,the column is divided to three regions: unconstrained region,weakly constrained region and constrained region.Constraint principle of stirrup and cross-shaped steel in concrete was analyzed,effective constraint area of stirrup and steel and confinement effectiveness coefficient of rectangular stirrup were calculated,the formulas for axial compressive strength of concrete restraint by stirrup and steel were suggested.Then the axial compression bearing capacity of the specimens was calculated,and the calculated results were compared with the current code provisions.The related work completed in this paper provides the experimental basis for the code and theoretical research of lightweight aggregate concrete,and it helps to promote the application of light-weight aggregate concrete in engineering practice. |
PDF Full Text Request