Seismic Performance Analysis Of Multi-story Stiffened Light Steel Keel System

The light steel keel composite wall is t the main load-bearing component of light steel joist structure system,which provides lateral resistance and bears vertical load.Improving the seismic performance and vertical load-bearing capacity of the structure is the key to the transformation of light steel structure system from low-rise to multi-story.In this paper,simplified analysis models of three-story light-steel keel dwellings with four different stiffened brace arrangements are established,and the seismic performance of each structure was analyzed.One of the composite walls with good seismic performance is selected to establish a four to seven-story light-steel keel structure.The vertical bearing capacity of the structure is considered by setting plastic hinges on the joist columns,and the seismic performance of each structure is analyzed Seismic performance and vertical bearing capacity.Simplified models of three-layer light-steel keel structure with 4 different stiffening bracing arrangements were established using SAP2000 software.Perform modal analysis and linear and nonlinear time history analysis on each model.The results show that the structural system consisting of diagonal braces arranged in an inverse figure on the side of the wall has the smallest natural vibration period,peak acceleration,maximum relative displacement and inter-layer displacement angle,and the overall stiffness is slightly higher than that arranged in the side span in the form of K,in the side span of the wall in the form of eight and in the middle of the span in the form of diamond,which can effectively reduce the acceleration,displacement and overall lateral deformation of the structure under various working conditions,and has stronger ability to resist the earthquake action.The weak layers of each structure appear on the first floor,and the maximum inter-layer displacement angle of each model meets the limit requirements of China's current "Code for Seismic Design of Buildings".under the earthquake action.Simplified analysis models of four to seven-story stiffened light steel keel structure system were established by using the light steel joist composite wall with diagonal braces placed in the side span of the wall to carry out basic dynamic characteristics analysis and seismic performance analysis,analyzing the structure period,acceleration,displacement,interlayer displacement angle and other performance parameters.From the results of modal analysis of different structures,it can be known that the "Technical Specification for Low-rise Cold-formed Thin-walled Steel Buildings" is proposed to calculate the first-order natural period of the structure is still suitable for multi-layer stiffened light steel keel structure system.Based on the analysis of the lateral displacement between floors and the relevant provisions in the "Code for Seismic Design of Buildings",this paper proposes that the limit value of the displacement angle between floors of a multi-layer stiffened light steel keel system is 1/500 in the event of frequent earthquake,take the 1/55 recommendation under rare earthquakes.In the light steel keel structure system,the wall frame columns are provided with plastic hinges of axial force to analyze the vertical bearing capacity of different structures subjected to earthquakes.Four to six-story structural systems did not produce plastic hinges under the effects of frequent and rare earthquakes.When the El Centro wave and Taft wave are acting,the maximum inter-layer displacement angle of the seven-story monolithic structure meets the limit requirements specified in the code "Code for Seismic Design of Buildings"(GB50011-2010),but under the action of an 8-degree rare earthquake,plastic hinges at the bottom single columns of the structure shows that the seven-story structure has good lateral resistance and insufficient vertical bearing capacity,so the bottom column should be strengthened.Under the action of the Tangshan wave 8 degree rare earthquake,the inter-layer displacement angle of the seven-story structure system increased significantly,exceeding the limit of the elastoplastic interlayer displacement angle of the seismic code,and plastic hinges appeared on the columns at the bottom of the structure.It may cause insufficient overall seismic performance of the structure.While strengthening the vertical load-bearing performance of the seven-story structure system,the horizontal lateral resistance of the structure should also be improved.According to the comprehensive analysis results,the stiffened light steel keel structure with diagonal braces arranged in an inverted octagonal shape at the side span of the wall can be built to six stories in the area of 8 degree rare earthquakes.