Research On Seismic Design Method Of Fabricated Concrete Column-Steel Beam Composite Frame Structure

Reinforced concrete column steel beam composite structure is a new type of building structure,which takes advantage of the excellent compression behavior of concrete,compression and tension of steel,and small dead weight of the structure.Assembled RCS composite joints have the characteristics of semi-rigid connection joints.Based on the previous experiments conducted by the research group,this paper conducts finite element simulation and parametric analysis on such joints,and obtains the impact of different joint configurations on the seismic performance of the joints.Based on the test results and finite element simulation results,the bending moment rotation model curve of the RCS composite joints is proposed.Based on domestic and foreign seismic design codes,four seismic performance levels of RCS composite frame structures are proposed,and the development process of plastic hinges is used as a quantitative indicator.Three types of RCS composite frame structures with different heights are designed,and static pushover analysis and dynamic elastoplastic time history analysis are performed using Sap2000.The seismic performance of these semi rigid connection joints and the limit values of story to story displacement angles at four seismic performance levels are obtained.Using the limit value of interlayer displacement angle and economic effect as reference values,the maximum applicable height of the RCS composite structure located at a seismic fortification intensity of 7degrees(0.15 g)is obtained.The main conclusions drawn in this article are as follows:(1)Based on the premise proposed by the research group,the performance of RCS beam column composite joints was simulated using validated finite element analysis methods and parameterized analysis was conducted.The results showed that the yield strength of steel beams and the width to thick Ness ratio of steel beam flanges have a significant impact on the bending bearing capacity of RCS joints,and the height of steel beams has a significant impact on the initial rotational stiffness of RCS joints.The trilinear bending moment rotation model curve of the RCS beam column composite joint is proposed,which is in good agreement with the experimental results and can be used as a reference for the design of RCS joints.(2)Based on the experimental research of domestic and foreign scholars on RCS composite frame structures,four seismic performance levels of normal operation,direct use,life safety,and collapse prevention of RCS composite frame structures are proposed.In SAP2000,validated multi segment plastic nonlinear connection elements were used to simulate RCS semi rigid connection nodes.A 3-story,6-story,and 9-story RCS composite frame structure was established and subjected to static pushover analysis.The development of structural plastic hinges and corresponding interlayer displacement angles were discussed.The results show that semi rigid nodes reduce the overall lateral stiffness of the structure,and the static pushover curve of semi rigid connection RCS composite frame structure is lower than that of rigid connection RCS composite frame structure,and the difference between the two increases with the increase of the number of floors.The interlayer displacement angle limits of the RCS composite structure under four performance levels of normal operation,direct use,life safety,and collapse prevention are 1/400,1/250,1/70,and1/50,respectively.(3)Applying RCS beam column composite nodes to prefabricated RCS composite frame structures,referring to the maximum applicable heights of cast-inplace reinforced concrete and steel structures in the specifications,a 15 story RCS composite frame structure(3.6m floor height)in a seismic fortification area of 7degrees(0.15g)is taken as the research object.Time history analysis was conducted on the structural loading of EI Centro waves,Taft waves,and artificial waves.The feasibility of the structure at various heights was analyzed based on the limit values of interlayer displacement angle and the amount of main materials used.The results showed that the maximum applicable height of the assembled RCS composite frame structure in seismic fortification areas of 7 degrees(0.15g)was 18 floors(65m).