| The eccentrically braced steel frame structure system has the advantages of high resistance to lateral stiffness and good ductility,and is widely applied in multi high-story buildings.But there are some drawbacks of this system: firstly,as a part of the frame beam,the link is difficult to repair and replace undergo the rare earthquake.Secondly,it is unpredictable that the cumulative effect of inelastic deformation caused by frequent earthquakes,which will increase the difficulty of assessing the degree of damage later.In view of the shortcomings of the eccentrically braced steel frame,the eccentrically braced steel frame with web-connected replaceable links is proposed in this paper.In this system,the link beam and the frame beam are separated and designed,and two components are connected through high-strength bolts.Meanwhile,the traditional eccentric brace is replaced by buckling-restrained braces of double-pipe with contact ring.The new system has the following advantages: Firstly,the separation design of the link beam and the frame beam can provide more choices for the section size and length of the link beam when the section size of frame beam is settled.Secondly,the inelastic deformation caused by rare earthquakes concentrates on the link beam,which ensures the safety of the rest of the components in the frame and reduces the difficulty of the security evaluation later.Thirdly,the link beam is spliced together with the frame beam by high strength bolts,which is convenient for the replacement of the link beam after the disaster.To sum up,the eccentrically braced steel frame with replaceable web shear links is of great significance for building assembly,assessment of structural safety and reinforcement and reconstruction after disasters.In this paper,the finite element software ABAQUS is used to establish the model.By applying the single-direction and cyclic load to the model,the influence of stiffener spacing,section size and length of the link on the mechanical properties such as energy dissipation capacity,bearing capacity and stiffness is analyzed by using the hysteresis curves obtained.Then,through the frame model of 1/3 scale was experimentally researched and the hysteretic curve,stress distribution and deformation of the test were analyzed.Compared with the finite element results and test results,the following conclusions were reached.(1)A finite element model of the eccentrically braced steel frame with a 25 th web-connected replaceable link was established.Under the single-direction load,a study was conducted on factors such as the stiffener spacing,section size and length of the link that affect the mechanical properties of the frame.(2)Analyze the finite element model under cyclic loading,use the obtained load-displacement curve to analyze the parameters such as the stiffener spacing,section size and length of the link for energy dissipation capacity,bearing capacity,stiffness,and plastic rotation angles.The influence of mechanical properties,the study found that the frame has good energy dissipation capacity,large lateral stiffness,good plastic deformation capacity and other advantages.(3)On the basis of finite element analysis,10 th web-connected replaceable link were tested on a 3th frame.By applying a cyclic load to the frame,the stress distribution and deformation,hysteresis curve,and skeleton curve of the frame and the stiffness degradation curve were obtained.It is found that the hysteresis curve of eccentrically braced steel frame is full and the seismic performance is good;only the link in the frame undergoes plastic deformation,and the rest of the components in the frame are in the elastic stage,which realizes the replaceability of the link.(4)Comparing the test results with the results of finite element analysis,it is found that the two have a high degree of coincidence and the shapes of the hysteresis curves are similar.The stress patterns and the deformation patterns have the same failure modes.The link can effectively control the strength and the stiffness of the overall frame,play the role of a fuse,indicating that the use of finite element simulation analysis is feasible. |
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