Study On The Anti-seismic Property Of Steel Frame Using Post-Buckling Strength Of Column Web

Steel structural construction is noted as one of21st century’s "Green Construction" which is a structure that is energy-saving, environmentally friendly and recyclable and meets the requirement of sustainable development for our country’s construction structure. As an independent branch of steel structure, light steel structure is often applied on single layer structures such as light-weight door-type steel structure. Along with the implementation of Technical specification for lightweight residential buildings of steel structure JGJ209-2010, light steel structure are increasingly applied on civil and public construction such multi-storey residence and office buildings. However, according to the Regulations, when the column axis pressure is large, construction shall still follow the regulations in Code for seismic design of buildings GB50011-2010, which makes light steel structure loosing its competitive edge. In order to make sure that under high column axis pressure the light steel structure can remain good anti-seismic property, to analyze the anti-seismic property of light steel structure, propose measures and methods to enhance the weak parts of the light steel structure and thus to make it meets the anti-seismic requirements for seismic zones through enhancing the weak parts under the premise of using the strength after column buckling are the fundamental purpose of this study. The research work and achievements of this paper are as follows:(1) Experimental tests are conducted on three light steel plane frames after using the strength of column web buckling under low reversed cyclic bearing action and a nonlinear finite element simulated program of light steel frame based on Abaqus Software is developed. Under the condition that the test results are verified as effective, the finite element program is implemented to deeply and systematically study the entire stress process and failure mode of steel frame, then the hysteretic curve, deformation, ductility performance and energy-dissipation capacity of steel frame are analyzed and finally the failure mode of joints area and failure mechanism of column base are studied in theory.(2) The influence the joints area shear deformation has on the lateral stiffness of light steel frame using the strength after column web buckling is analyzed in theory. Considering the fact that even by adopting the methods in Code for design of Steel Structures GB50017-2003and Code for seismic Design of buildings GB50011-2010that are currently in force to enhance the joints area, joints area shear deformation still exists, the developed finite element program is implemented to deeply and systematically study the anti-seismic property of reinforced mid-side joints, anti-seismic property and failure mode of light steel frame mid-side joints under different reinforcement methods are analyzed, the conclusion that reasonable mid-side joints area plate thickness should be no greater than (hc+hb)/65is reached and verified.(3) Experimental tests are conducted on mid-side joints of two light steel plane frame after using the strength of column web buckling under low reversed cyclic bearing action and nonlinear finite element program are used for simulation. Under the condition that the test results are verified as effective, considering the fact that under large axis stress ratio, there is buckling at the column ends near the joints area of light steel frame using the strength after column web buckling, the finite element program is adopted to deeply and systematically study the influences the reinforcement methods for penetrating web and flange have on the bearing capacity and anti-seismic property of mid-joints, the hysteretic curve, deformation, ductility performance and energy-dissipation capacity of steel frame are analyzed, the effect on the above properties different parameters have are studied in theory and thus reasonable mid-joints reinforcement measures and methods are proposed.(4) Based on the achievements reached in the study, the reinforcement of mid-side joints and mid-joints of light steel frame and the anti-seismic property of reinforced joints light steel frame using the strength after column web buckling are studied and the influence that different column web ratios of height to thickness have on anti-seismic property and bearing capacity of this type of light steel frame are deeply and systematically studied. The study shows that reinforced joints light steel frame has better bearing capacity and can effectively reduce structure lateral sway and deformation while keeping good anti-seismic property. Besides, measurement index using ductility coefficient as basal ration, relation curve between ductility coefficient and ratio of height to thickness of column web, the conclusion that57should be the value column ratio of height to thickness when axis ratio is0.4and classes of seismic measure is4all provide theoretical references for light steel frame column design.In conclusion, the reinforced joints of light steel frame proposed in the paper meets the requirements of our country’s anti-seismic design regulations and limiting value of column web ratio of height to thickness of reinforced joints light steel frame using the strength after buckling can both satisfy anti-seismic requirements and reduce structural steel usage and is cost-saving which provide technical support for light steel frame usage in seismic regions in the future.