Study On Resilience Behavior Of Concrete Columns With Stainless Steel Bars

Steel corrosion is one of the most important factor affecting durability,and the corrosion resistance of stainless steel rebars can solve this problem.However,at present,there are few researches on the configuration of domestic stainless steel rebars members,and the current research has basically belonged to the performance analysis under static load.Thus,the research data on earthquake resistance is too little to meet engineering application requirements.In order to promote the application of stainless steel reinforcement in concrete structures and improve structural durability,it is necessary to focus on the further study of the mechanical properties of the domestic stainless steel rebars members.The resilience performance of the domestic stainless steel reinforced steel columns was studied by experiments and simulations,and the research contents are as follows: the mechanical properties differences between 500 MPa stainless steel rebar and HRB500 rebar under monotonic tensile load are compared;Based on the experimental research,a nonlinear finite element analysis of the factors affecting the seismic performance of stainless steel rebars columns(axial compression ratio,concrete strength,reinforcement ratio)is done by OpenSEES;and based on numerical analysis data,a restoring force model of stainless steel rebar columns is established,which is planted into the secondary development platform of OpenSEES,then a stainless steel reinforced concrete portal frame is constructed,compared to a similar HRB500 one.Conclusions are as follows:(1)The comparison of two stainless steel rebars columns in the pseudo static test shows that the stiffness degredation of the lower axial compression ratio is flatter and the energy consumption is better,and its ultimate displacement angle is lager,meaning greater seismic performance;the equivalent viscous damping coefficient of the higher axial compression ratio of the specimen is larger,which means stronger energy consumption capacity,but its damage is more;when the axial pressures of the two specimen are silmilar,the horizontal force peak value is also similar.(2)Comparing the stainless steel rebars columns with HRB500 one in the pseudo static test,it can be concluded that the yield displacement angle,ultimate displacement angle and the equivalent viscous damping coefficient of stainless steel rebars columns are larger than HRB ones,while its displacement ductility coefficient is smaller.The bearing capacity degradation coefficient of HRB ones decreases gradually with the increase of the displacement,while the stainless one shows a fluctuating change.In the later stage of loading,both bearing capacity degradations are serious,but the stainless steel one is more serious.(3)The parameters analysis of stainless steel reinforced concrete columns shows that: the bearing capacity of column increases with the increase of reinforcement ratio,concrete strength and axial compression ratio.But when the reinforcement ratio is 5.113%,the bearing capacity increases when the axial compression ratio changes from 0.2 to 0.3.However,when the ratio is changed from 0.3 to 0.4,it decreases.The ultimate displacement angle decreases with the increase of the axial compression ratio and concrete strength,while it increases when reinforcement ratio increases;then,the displacement ductility coefficient increases when reinforcement ratio increases,and there is no obvious change when the concrete strength increases,and as the axial pressure ratio increases,it gradually decreases.(4)Comparing the parameters analysis of stainless steel column with the collecting HRB500 steel columns test results,there are some similarities as follows: as the longitudinal reinforcement ratio and the axial compression ratio increases,the bearing capacity gradually increases;and as the axial compression ratio increases,the ultimate displacement angle,and the displacement ductility coefficient decreases.Meanwhile,the differences include: the displacement ductility coefficient of stainless steel reinforced columns is smaller than that of HRB500 ones;and longitudinal reinforcement ratio increases,the ultimate displacement angle of stainless steel rebars columns gradually increase,while the HRB500 one is the opposite.This is because the collected HRB500 steel column test results are discreted and the hoop characteristic values are not completely consistent.(5)Comparing the seismic performance of stainless steel portal frame with the similar HRB500 one during the low cycle reciprocating loading,the following conclusions are drawn: the stainless steel frame is larger than the HRB500 one in yield displacement,ultimate displacement and displacement ductility coefficient;stainless steel frame has more stable stiffness degradation and better seismic performance;and it has larger viscous damping coefficient and stronger energy consumption.