Seismic Mechanism And Shaking Table Test Of Buckling-restrained Braces Structure

Buckling-restrained brace is an excellent passive metal energy dissipater.It can not only serve as an ordinary brace in the structure to improve the stiffness of the structure,but also rely on its own characteristics to solve the problem such as easy yield of the ordinary brace under earthquakes.The seismic energy is dissipated by the plastic deformation of the core element when the brace is in tension or compression.Buckling-restrained brace has the characteristics of simple installation,low cost and flexible layout.When the buckling-restrained brace is erected in the frame structure,it can take the lead in energy dissipation and act as a fuse when the structure is subjected to earthquake.Therefore,the buckling-restrained brace structure becomes an efficient seismic structural system,which has a wide application prospect in engineering.In this paper,through the reference of many related professional literatures,experimental research,theoretical design and numerical simulation,the systematic research on the buckling-restrained brace structure is carried out and the relevant design opinions are put forward.The main research results of this paper are as follows:(1)The seismic performance of buckling-restrained brace with low-yield-point steel inner core which was designed and manufactured in the factory for the scientific research intent was investigated.The shaking table tests about two different structures of ordinary pure steel frame and buckling-restrained brace structure under three earthquakes with the increasing peak ground accelerations were carried out.The mechanical properties of these two structures in terms of the failure mode,dynamic characteristics,acceleration response,inter-story drift angle,strain distributions and inter-story shear response under different intensity levels of seismic waves were discussed.The improved performance on the structural seismic response for the buckling restrained brace was further analyzed and evaluated by the experimental results.(2)The finite element software of SAP2000 was used to conduct the numerical simulation of the buckling-restrained braced structure and pure steel frame under the earthquake action.Many significant seismic parameters such as the natural mode of vibration,inter-story displacement,acceleration response,and inter-story shear force of these two different structures under the action of different earthquake waves were obtained.Through the comparative verification of simulated results with the test,the seismic performance of buckling-restrained braced structure was further analyzed and improved.(3)The theoretical design method of buckling-restrained brace was studied.Combined with the relevant codes at home and abroad,the specific design formulas of essential parameters used for the engineering application such as the bearing capacity of core element,overall or local stability of constraint element,core element and connection section in the buckling-restrained brace,and the interval value between constraint element and core element were analyzed and discussed.Through the provided theoretical method,an example of buckling-restrained brace was designed and verified.(4)Based on the finite element software of ABAQUS and ABAQUS/CAE module,the mechanical properties of the rectangle shape buckling-restrained brace were analyzed.According to the theoretical design,the parametric design analysis of the buckling-restrained brace is carried out.Through the research of the influence of the initial geometric defects,friction,width-to-thickness ratio of the core elements,interval distance,restraint ratio and other factors on the energy consumption of buckling-restrained brace,the theoretical method of this structure is further improved.(5)Three kinds of structures including the buckling-restrained brace steel frame,ordinary brace steel frame and pure frame were designed.The different seismic performances of these three structures were analyzed by using the finite element software of SAP2000.In addition,the theory of pushover analysis is also introduced to carry out static elastoplastic analysis for three kinds of structures under the inverted triangle loading distribution and uniform loading distribution.The distribution of plastic hinge,inter-story shear force,inter-story drift angle,vertex displacement and failure mode of three kinds of structures were compared in detail,and the overall seismic performance evaluation of the steel frame structure with buckling-restrained brace was made.