Experimental Study On Seismic Performance Of Precast Steel Reinforced Recycled Concrete Frame

Prefabricated steel reinforced recycled aggregate concrete structure(PSRAC)is a combination of recycled aggregate concrete(RAC)structure,steel reinforced concrete(SRC)structure and prefabricated structure.The structure system can improve the internal defects caused by the damage of recycled aggregate in the RAC structure,and the disadvantages of the prefabricated structure such as insufficient energy consumption and poor seismic performance.It can also have the advantages of high bearing capacity,good seismic performance,saving resources,ensuring the quality of the project and shortening the construction period.At present,the research on the performance and design method of PSRAC structure is basically blank at home and abroad.In order to study the seismic performance of PSRAC structure,this paper designed and produced two trusses of precast steel recycled aggregate concrete frame(PSRACF)with the replacement rate of 100%recycled aggregate.The axial compression ratio of the two trusses is different,and other structural forms are the same.The failure process and failure mode of the PSRACF structure were revealed through the experimental study on the production process and seismic performance of the PSRACF structure.The mechanical properties of the structural system,such as hysteretic performance,skeleton curve,bearing capacity,stiffness and stiffness degradation,ductility,energy dissipation,plastic rotation Angle,self-reset ability,P-Δeffect,were analyzed.The simplified calculation formula of PSRACF structure bearing capacity is put forward,and the suggestion of PSRACC structure design is given.The main contents and conclusions are as follows:(1)PSRACF structure in the beam-column,column-column connection parts using dry connection,reduce the amount of wet work on the construction site,disassembly is convenient and fast,with a short construction period,fast speed,can be repeatedly used advantages.(2)Cracks in the PSRACF structure are mainly distributed in the post-cast section of beams,columns and the interface joint of the post-cast section in the beam-column splice area.There is no obvious damage in the core area of the beam-column joints.With the increase of the axial compression ratio of the specimens,the damage degree of the specimens increases.(3)The restoring force curves of the two PSRACF structures with different axial compression ratios are relatively full;The equivalent viscous damping coefficient is between 0.15 and 0.2,and the h_e of reinforced concrete structure is consistent(0.1<he<0.2).The larger the axial compression ratio,the smaller the energy dissipation coefficient and the worse the seismic performance.(4)The strength attenuation degree of PSRACF structure increases with the process of loading.The greater the axial compression ratio,the greater the strength attenuation degree will be.The effective stiffness of PSRACF structure is about 0.75-0.83 times of the initial tangent stiffness.The larger the axial compression ratio is,the greater the stiffness and stiffness degradation rate of specimens will be.(5)The larger the axial compression ratio of PSRACF structure is,the worse the plastic rotational capacity is.The average plastic rotation Angle of PSRACF100-1 is0.0375rad,which is larger than the limit of 0.02rad in seismic design code.The ductility of the specimen is 3.88,which meets the requirements of the specification.The displacement Angle of cracking point is greater than the limit value of 1/550 required by the code,and the displacement Angle of failure point is greater than the limit value of 1/50 required by the code,indicating that the PSRACF structure studied in this paper has relatively excellent deformation ability and collapse resistance.(6)The residual deformation of PSRACF structure is positively correlated with the loading displacement of each stage,and the influence of axial compression ratio on the residual deformation is not obvious.There was a negative correlation between the reset ability of specimens and the displacement of each loading stage,and the axial compression ratio had a significant effect on the reset ability coefficient of PSRACF structure.With the increase of loading displacement,the P-Δeffect of PSRACF structure gradually increases,and the greater the axial compression ratio,the more significant the P-bit effect.(7)The simplified calculation model can better calculate the bearing capacity of this kind of PSRACF,and the measured value is in good agreement with the calculated value.(8)Based on the working conditions in this paper,some design suggestions are put forward on the physical properties of raw materials used in the PSRAC structure,ratio,construction measures and connection forms of prefabricated parts,etc.,to provide reference for the design of PSRAC structure.