The Seismic Performance Of Buckling Restrained Braced Frames With Eccentric Configurations

Eccentrically braced frame(EBF) is a new type of lateral earthquake resistant system with good performance under the earthquake loads. In order to dissipate earthquake energy, EBF beam regions(called links) must suffer from large inelastic deformations, thus, the EBF energy dissipation beam with column connections, especially the welded link-to-column connections, often tend to brittle fracture because of the large bending moments and shear forces transmitted by the link rotations. As an important member of the structure systems with energy dissipation, buckling-restrained braces(BRB) will not be buckling under compression, which have good mechanical properties and energy dissipation capacity. Buckling-restrained braced frames(BRBF) with braces in eccentric configurations(EBRBF), which is the main structure investigated by this study, comes when combine EBF with BRBF. In order to protect the main frame structure, BRBs under earthquakes will yield to dissipate energy firstly, which is a new type of energy dissipation damping structure in recent years.However, the traditional design methods use the strength design theory, which cannot guarantee the ideal model of damage when the structure is in the elastic-plastic stress state. In this study a new design procedure based energy and plastic design concepts is applied to EBRBF. Under inelastic deformation state, the target displacement and the yield mechanism of EBRBF structures are pre-selected firstly, then the base shear and lateral shear distribution of the structure are derived from the modified energy balance principle under rare earthquakes, and then design the sections of BRBs,then the design of the peripheral beam-column members using the capacity design method, to ensure that the structure get the needed strength and forms an ideal yield mechanism. A 12-story EBRBF case designed by the proposed PBSD method is modeled with Open Sees,and the Pushover and elastic-plastic time history method is used to obtain the seismic response analysis of the structure.the analysis results show that the case designed by the proposed method has reached the target design, at the same time, the story drift under the rare earthquake has meet the requirements of the specification, the BRBs yield with energy dissipation first,the structure also shows ideal yield mechanism, which proved The seismic performance of eccentrically braced frame with buckling-restrained braces is very good.