Study On Seismic Performance Of Concrete Core-separated Column And Platform Canopy Structure

As a kind of infrastructure widely used in the design of middle and small types railway stations,single-column canopy is a statically determinate system lacking redundant constraints in the direction normal to colonnade.Compared with the direction of colonnade which is similar to the spatial frame structure,the structure in the direction normal to colonnade can not fulfil the requirement of seismic ductility design in current seismic codes that plural seismic fortification lines should be set up in structure.Therefore,there may be hidden danger in structure which can not be ignored.In order to ameliorate the mechanical performance of single column and solve the problem these structures have poor seismic performance in direction normal to colonnade.This paper innovatively put forward a new type of member named "Concrete Core-Separated Column".According to the actual engineering background,the seismic performance of this column is Researched synthetically by analysis method combining experiment and simulation.The main work and research results are as follows:(1)Considering the actual engineering situation,the scaled models of two new-type members,the core-separated column with sliding connection and the core-separated column with concrete connection,are designed and made.Through the pseudo-static test,the seismic performance of concrete core-separated column,including hysteresis,skeleton curve,ductility,longitudinal reinforcement strain,stiffness and strength degradation,is comprehensively analyzed and studied.The results show that the new-type columns have good seismic behavior in all aspects,and inner column with great integrity can prevent structure from collapse when outer column has been damaged seriously.(2)The precise numerical analysis model of the new-type column is established by ABAQUS,and the simulation of the cyclic loading test is completed by selecting the material constitution and model parameters reasonably,optimizing mesh and defining the appropriate contact and constraint relation.Through the contrast,the simulation model is in good agreement with the test in the aspects of hysteresis,skeleton curve,strength and stiffness degradation,etc,which proves the rationality of the finite element model.Combined with the test results,the specific mechanical behavior of this new-type column and the cause of great seismic behavior are verified.(3)Based on reasonable model obtained from simulation,two groups including 18 models for parametric analysis are established and used in finite element analysis under cyclic loading.The influence of these parameters,including diameter ratio of inner and outer columns,reinforcement ratio of inner and outer columns,the length and depth of connection,on the seismic behavior of new-type columns,such as energy dissipation capacity,bearing capacity,ductility,stiffness degradation,is studied.On these grounds,optimized design suggestions for this two new-type members are put forward preliminarily.(4)Based on optimized design suggestions,combined with the actual engineering background,platform canopy supported by new-type columns in the area of 0.2g of 8degrees is designed after the rigidity and strength equivalence of the core-separated column with sliding connection and ordinary reinforced concrete column are completed,and the nonlinear seismic response analysis that 8 horizontal ground motions are input onto this structure in the direction normal to colonnade is carried out.The results show that the platform canopy using new-type column as structural column can fulfil the seismic requirements of "No Collapsing in the Strong Earthquake" in the direction normal to colonnade,and the ductility of single column greatly exceeds the structural ductility requirements under rare earthquakes.At the same time,the structural damage analysis shows that the damage of inner column is much better than that of outer column,which really achieves the goal of ductile design that plural seismic fortification lines should be set up for platform canopy in the direction normal to colonnade.Finally,some preliminary design suggestions are put forward.