Research On Seismic Performance And Design Method Of Rocking Damping Steel Frame

The rocking damping steel frame(RDSF)is a new type of shock-absorbing structure system,which relax the constraint between the column bottom and the foundation by setting the rocking column foot,the bucking-restrined brace(BRB)and the friction damper at column foot(FDCF)provide additional damping ratio for the frame.On the one hand,BRB provides sufficient lateral stiffness for the frame under small earthquakes,the rocking column foot does not uplift and FDCF does not participate in energy dissipation.On the other hand the rocking column foot uplifts under large earthquakes,FDCF and BRB dissipate energy at the same time.In order to study the seismic performance of RDSF,the research group has completed two seismic tests and the test results are good.However,the analysis of related parameters related to the RDSF is not complete due to test limitations.Therefore,this paper further analyzes the seismic performance of RDSF,proposes the goals of performance design and design methods for RDSF based on the results of parameter analysis,and verifies the applicability of the design methods at the same time.Based on the test group's two tests of rocking damping steel frame,the finite element models of the test frame are established and compared with the test results to verify the correctness and applicability of the finite element model.The first test frame is named as the rocking bucking-restrained braced steel frame(RBRBSF),and the second test frame is named as the bucking-restrained brace-rocking steel frame(BRB-RSF).Parameter analysis is based on the finite element model of RBRBSF.The results show that the nominal lateral stiffness ratio(?)and the yield strength ratio(?)between numerical model of the friction damper at the column foot and BRB are the key parameters affecting the response of RBRBSF,and which changes greatly with the change of each key parameters are the lateral displacement of the frame,the uplifting height of the column foot,the cumulative energy dissipation and energy dissipation ratio of the energy dissipating element.At the same time,the influence of post-tensioned prestressed tendons and semi-rigid beam-column joints on the response of frame are analyzed based on the finite element model of BRB-RSF.The results show that the slip between the bottom beam and the bottom of colum is limitted by setting post-tensioned prestressed tendons,and the semi-rigid beam-column joints have adversely affected the energy dissipation of the BRB.Therefore,comprehensive analysis determines that no additional post-tensioned tendons and semi-rigid joints are added to RDSF.The structure of the two test frames are one-story one-span steel frame but the response of the steel frame will be greatly affected by the weight of the side span and the superstructure in actual engineering,so a finite element model of multi-layer multi-span RDSF is established.Analyze the effect of ? on the frame and determine the optimal value range of ? by using the lateral displacement of the frame and the capacity of energy dissipation of the energy-dissipating elements as the control value.The influence of ? on the frame is analyzed using the uplifting height of the column foot and the energy dissipation capacity of the energy-dissipating elements as the control values,and the optimal value range of ? is determined.At the same time,the weakest frame analysis is performed based on the optimized range of ? and ? to determine the critical point of elastic design for the pure frame corresponding to different ?.The analysis in this section provides data support for the optimization of the design process of RDSF.Based on the above analysis results,the conceptual design principles and performance design goals applicable to RDSF are clarified,and the performance design steps optimized for RDSF are proposed.At the same time,6-layer,12-layer,and 18-layer RDSF are designed based on the design steps.On the one hand,the beam-column cross-section dimensions are preliminarily selected through load statistics,on the other hand,the beam-column cross-section dimensions are adjusted based on the elastic design results of pure frame,and the key design parameters of the shock-absorbing elements are calculated to complete the design of the shock-absorbing elements.Finally,the applicability of the design method is verified by elasto-plastic time history analysis of RDSF.The results show that the design method proposed in this paper is suitable for RDSF,shortening the calculation process of selecting relevant parameters,and the multi-layer optimization and multi-step discrimination optimization design process ensures the rationality of RDSF.