Compressive Behavior Of Rectangular RACFST Stub Columns

As a kind of environmental-friendly material,recycled aggregate concrete(RAC)is able to solve the problem of waste concrete management,save natural resources and protect the environment,which has significant social,economic and environmental benefits.RAC filled steel tube(RACFST)can effectively improve the weaknesses of RAC and achieve the aim of effectively recycling waste concrete resources,because outer steel tube can provide confinement to core RAC and protect core RAC from the influence of the natural environments.At the same time,rectangular concrete filled steel tube(CFST)can also effectively improve the bearing capacity and ductility of structural members.In addition,rectangular CFST stub column is convenient for internal space layout and connection to beams,which has received extensive attention and application in the practical engineering.In this paper,the compressive performance of rectangular RACFST is experimentally and theoretically investigated,and the main works are summarized as follows:(1)To investigate the effect of recycled coarse aggregate replacement ratio,depth-tobreadth ratio,thickness of steel tube on the failure patterns,load versus deformation curves,bearing capacity and composite elastic modulus of rectangular RACFST stub columns,a total of 18 specimens are tested.(2)Based on the determination of constitutive model for steel and core RAC,the finite element analysis model is developed for the simulation of rectangular RACFST stub columns.The simulated mechanical properties generally agree well with the experimental results.(3)The influence of recycled coarse aggregate replacement ratio,depth-to-breadth ratio,steel ratio,yield strength of steel and original concrete strength on the mechanical properties and mechanism of rectangular RACFST stub columns is investigated using the finite element analysis model.(4)Based on the parametric analysis results,the simplified formulae for the bearing capacity of rectangular RACFST stub columns is proposed,and the predicted results using the simplified formulae are generally accord well with the experimental ones.