Study On Seismic Behavior And Seismic Design Methods Of Steel Reinforced Recycled Concrete Frame Structure

The steel reinforced concrete composite structure has a high bearing capacity andgood seismic performance. At the same time, the recycled concrete can save energy andprotect environment, which has the characteristics of renewable utilization. Combinedwith the above characteristics, the steel reinforced recycled concrete composite structure(SRRC)was put forward in this paper. The new structure can not only improve theearthquake resistance ability of building structure, but also accord with the strategies ofnational green environmental protection and sustainable development. Therefore, thesteel reinforced recycled concrete composite structure has a broad applicationprospects.The basic mechanical behavior and seismic perfoemance of SRRC beamsand columns have been studied.In this paper, through the test and theoretical methods,the mechanical properties of steel reinforced recycled concrete joints and frame underlow cyclic loading were researched in detail. The design calculation methods of jointswere also put forward in this paper.The main research work is included in the fouraspects as following.(1)Experimental study and theoretical analysis on seismic hehavior of SRRCbeam-column joints.According to the experimental study on41:2.5beam-column jointspeciments under cyclic loading,the bearing capacity, deformability, stiffnessdegradation,ductility and energy dissipation of the beam-column joints of SRRC framewere studied.The failure mechanism of the beam-column joints under cyclic loadingwere investigated.The results show that the beam-column joints of SRRC frame havegood ductility,strong deformation ability and high energy dissipation,therefore haveadvanced seismic behavior.Based on the failure mechanism of the beam-columnjoints,the calculation formula of shear capacity was given. (2) Experimental investigation and theoretical analysis on seismic behavior ofSRRC frame structure. According to the experimental study on a two-bay and three-story1:2.5model of SRRC frame structure under pseudo-dynamic test,the seismic responsessuch as acceleration,displacement, varying stiffess,hysteretic property and energyconsumption were analyzed. The results show that the SRRC frame structure has goodductility and strong plastic deformation capacity. The maximum story drift angles of themodel structure under intensity8frequent and rare earthquakes are all less than their limitvalues regulated by the present seismic code. SRRC frame structure satisfied the demandof seismic design in8intensity zones,and has good seismic behaviors. After thepseudo-dynamic test, the experimental study on the model of a two-bay and three-storySRRC frame structure under low cyclic reversed loading was to do. The failure conditionof frame structure was observed. The load-displacement hysteretic loops and skeletoncurve of tested model were obtained. The failure mechanism, hysteretic behavior,ductility, energy dissipation capacity and stiffness degeneration were investigated. Theresults show that the failure mechanism of SRRC frame structure is the first occurrence ofbeam-hinge and then column-hinge mechanismn,and the first occurrence of joint-hingeand then member-hinge machanism.The hysteretic loops were a plump. Whendamaged,the maximum angle of displacement is1/22. The average of the overallductility factors is greater4.3. The steel frame-bent structures exhibits excellent seismicbehavior, and can be adopted in high seismic fortification zones. The inter-storydisplacement rotation is relatively large on the bottom floor and the second floor, namelythe weak floor.(3)Nonlinear finite element analysis on seismic behavior of SRRC beam-columnjoints and SRRC frame structure.According to mechanical characteristics of SRC,aconstitutive relationship applied for SRC material under cyclic loading is built.Based onthe above experimental investigation,considering the influence of nonlinearity ofmaterial geometry and rigidity degeneration and so on,the bearing capacity ofbeam-column joints and hysteretic characteristics of structure of the SRRC frame wereinvestigated.The calculated results were much coincided with the tested results.Combined with the characteristics of steel reinforced recycled concrete frame andsimplified processes, the OpenSees software was used for simulating the hysteretic behaviors of steel reinforced recycled concrete frame under low cyclic loading. Thehysteresis curves and skeleton curves of frame were obtained. The simulation resultsand test results were compared, which verified the rationality of finite element analysisresults. On the basis, the influences of P-? effect,axial compression ratio,recycledconcrete strength grade and steel strength on seismic performance of the frame wereanalysed in detail.(4)Referring the current codes, four performance levels are put forward for SRRCframe, which are full operation, temporary operation, life safety and collapse prevention.The four performance levels and three seismic levels are combined to form the seismicperformance target,respectively as the highest goal,important objective and basic goal.Based on the results of seismic performance tests on SRRC frame, the maximuminter-story drift angle corresponding to different performance levels were presented forthe SRRC frame.Performance-based seismic design theory was applied to the SRRC frame. Againstthe structural characteristic, the design procedure was given, and taking eight-storyframe as an example, the design process was demonstrated. Besides, the design methodsof member section of SRRC frame were proposed by generalization and analysis.