Analysis And Evaluation On Seismic Performance Of Seismic-Damaged SRC Frame Structures Strengthened With Enveloped Steel Jackets

With the extensive application of reinforcement engineering,it is of great engineering value to evaluate the seismic performance of seismic-damaged structures after reinforcement and repair,and judge whether the reinforcement structures meet the requirements of seismic fortification and achieve the effect of damage repair.In this paper,based on the experimental study on seismic performance of seismic-damaged steel reinforced concrete(SRC)frame structures strengthened with enveloped steel jackets,reasonable finite element analysis models were established by using open source software OpenSees.The seismic performances of SRC frame structures strengthened with enveloped steel jackets were analyzed and evaluated,and the influencing factors of SRC frame structures strengthened with enveloped steel jackets were analyzed.The research contents of this paper were as follows.(1)Establishing the numbercial model of SRC frame structures strengthened with enveloped steel jackets.Considering that the restraint effect of the enveloped steel jackets is similar to that of stirrups,the constraint strengthening coefficients were calculated by adjusting the existing uniaxial constitutive model of confined concrete.For the fine division of reinforced SRC fiber section,the fibers of different uniaxial material constitutive models were defined to simulate their different stress-strain relations.The numerical model of SRC frame structures strengthened with enveloped steel jackets can be established and verified.(2)The method of reducing material properties was used to simulate seismic damage.Using the appropriate damage model to calculate the damage index as the parameter,the reduction coefficients of material strength and stiffness were calculated to define the damage of each member in the structures with moderate and severe seismic damage,and the numerical model of the moderate and severe seismic damaged SRC frame structures strengthened with enveloped steel jackets were established and verified.(3)Analyzing the influences of test parameters on the reinforcement effect of seismic-damaged SRC frame structures.Pushover analysis of the established numerical models were carried out,and the seismic performances were evaluated by indexes,as target displacement,story drift ratio and plastic hinge distribution.The influences of test parameters such as test axial compression ratio,enveloped steel jackets strength and concrete strength grade on the reinforcement effect were also analyzed.