Research On Plastic Design Method And Seismic Performance Evaluation Of Staggered Truss Steel Framing Structure Based On Energy Balance

At present,the staggered truss structure is mainly applied in low-intensity areas,which greatly limits the application range of the structure system.Because staggered truss has the advantages of less steel consumption,large-span space without column and low foundation cost,it is also attractive to the high-intensity area.Therefore,in order to further promote this efficient,practical and economic structural system,it is urgent to improve its seismic performance.In order to control the damage distribution in a certain ductile section,reduce the rotation demand of chord for the single Vierendeel staggered truss after plastic design,and improve the seismic performance of staggered truss,a plastic design method based on energy balance is derived according to the performance-based plastic design(PBPD)of Goel.The method is applied to the design of the staggered truss structure with three Vierendeel segments,which expands the proportion of the length of the truss ductility segment,and the designed structure is evaluated.The main research contents and achievements are as follows:(1)For three Vierendeel and single Vierendeel ductile staggered truss steel structures,the plastic design method based on energy balance is theoretically deduced,and the plastic design process of ductile staggered truss steel structure is proposed.The ABAQUS refined finite element analysis model of three Vierendeel internode truss element is established,the parameter analysis is carried out,and the recommended range of the stiffness ratio of chord and vertical web in the ductile section is proposed,so as to realize the expected failure mode of yield energy consumption in the ductile section.(2)Based on the derived plastic design method and the same design information,an8-story three Vierendeel internode ductile staggered truss specimen MTP and an 8-story single Vierendeel internode ductile staggered truss specimen STP are designed respectively.At the same time,an 8-story single Vierendeel internode common staggered truss contrast specimen STE(without plastic design)is designed based on the standard design method.The finite element analysis software SAP2000 is used to analyze the response spectrum and pushover of three specimens under frequent earthquakes.The response spectrum analysis shows that the three specimens can meet the requirements of relevant codes under frequent earthquakes,and the ductile staggered truss with plastic design can make the displacement angle between layers more uniform,but the specimens without plastic design have obvious weak layers.The pushover analysis results show that the three Vierendeel staggered truss structure and the single Vierendeel staggered truss structure can meet the needs of frequent and rare earthquakes,and the plastic hinge distribution of each layer is relatively uniform under the target displacement state,and the expected yield mechanism can be realized.(3)The finite element software SAP2000 is used to analyze the dynamic time history of two plastic designed specimens under frequent earthquakes,and the dynamic time history of three specimens under rare earthquakes.The results show that all members of the two plastic designed specimens remain elastic under frequent earthquakes.Under the rare earthquake,compared with the three Vierendeel ductile staggered truss,the single Vierendeel ductile staggered truss has a higher demand for the rotation of the chord.In the second floor with the largest rotation demand,the demand for the plastic angle of the chord reaches 0.102 radian;The results show that the displacement angle distribution of three Vierendeel ductile staggered truss specimens and single Vierendeel ductile staggered truss specimens after plastic design is more uniform than that of single Vierendeel ordinary staggered truss specimens without plastic design,which reduces the possibility of weak layer and forms a damage controllable yield mechanism: the mid span ductile section of staggered truss yields and consumes energy,The damage caused by seismic energy is concentrated in the ductile section,and the non ductile members(except the column bottom)are in elastic state.