Analysis Of Anti-seismic On Storey-adding Frames Of Light-weight Steel With Buckling Restrained Braces

As China's economic developing fast, many old low-rise housing cost a lot of floor space and cause a low land utilization rate.In many ways,that can not meet the requirements of the times.Remove and reconstruction resulting in huge financial input and waste,and a lot of construction waste is a serious environmental pollution in the city. So it is urgent to study storey-adding of existing buildings.As a new technology, storey-adding structure of light-weight steel has been getting more attention.Adding steel layer on the top of the concrete structure is widely used in practice due to its advantages of lightness and good anti-seismic properties.Conventional brace is prone to buckling under pressure of earthquake,and quit work, this led to the rapid decline of the overall stiffness and is harmful to the structure. Buckling-Restrained-Brace (BRB)is a brace which could avoid buckling.Even in the relatively large structural deformation,the brace can provide structural strong lateral stiffness,and because of yielding of the core components,the brace can give full play to their energy performance.Set BRBs between columns in multi-layer concrete frame or steel frame to form a system called energy dissipating brace frame,is a new earthquake resistant structure which have obviously vibration-suppressing effect.But at the present time,studies on BRBs'application in frame construction much concentrate on pure concrete frame and steel frame,and little analysis is made for storey-adding structure.This text is on the basis of a project to do in-depth research on BRBs'anti-seismic function in storey-adding structure.First, with the help of finite element software ANSYS,the time history analysis is done to analyze storey-adding structures with two steel stories on top of three concrete stories'frame;Then discusses the effects on seismic characteristics of structures with different numbers of storey-adding,and the structures'arching effect;Finally, BRBs'lay rules and damping performance are analyzed through different arrangement plans.The results show that,BRBs have brought fine functions into increasing structure stiffness,diminishing storey displacement,and energy dissipation ability. Taking a reasonable cross-section area and layout of BRBs can make sure the structure under earthquake meet the earthquake-proof standards.