The Seismic Performance And Design Method Of High-rise Buildings Steel Structure With Buckling-restrained Braces

The conventional frame-bracing systems have solved the problem of lateral rigidity to a certain degree.However; the braces will be buckled because of compression when earthquake and wind loads apply to the structures. In order to satisfy the design requirements, the cross-sectional areas of the braces have to be magnified and the economical efficiency of the structures will be reduced. The buckling-restrained brace has overcome the disadvantages of the conventional brace which can yield in both tension and compression without buckling to dissipate the energy imparted to the structure during earthquake excitations and the seismic performance of the structure will be enhanced. In this paper the basic principles, composition features and experimental investigation of buckling-restrained brace have been introduced firstly, then the equivalent stiffness of the brace has been deduced and the influence of concentration factor have been discussed.This paper has made use of finite element software SAP2000 to carry on the time-history analysis for two kinds of frame-bracing structure. According to the analysis results, the seismic performance of frame structure with buckling-restrained braces is better than conventional braced frame structure. The influence of initial stiffness ratio,stiffness coefficient after yielding as well as the arrangement way of braces to seismic performance of structures have been discussed.In response to the parameter influence curve,the suggestion value of engineering design has been given in the follow. In the later part of the paper,the basic principle of energy-based design method has been expounded and the energy equation has been given. In addition, the influence factors of the distribution of seismic energy between stories have been discussed.Compared with the conventional design methods, the energy-based seismic design method is difinite,simple and effective which can be used into engineering design.In the end, the paper has given the simplified procedures of energy-based seismic design method of frame structure with buckling-restrained braces to make the references to engineering design.The problem of further study is how to apply the theory of optimization to frame structure with buckling-restrained braces to seek the best balance point between the damping effect and economic results. Another problem is how to establish uniform energy design theory and to set down the regulations of energy-based seismic design which can be applied to practical engineering.