Seismic analysis on braced steel frames with unbonded brace encased in wall panel and with hinged beam-column connection in braced span

An analysis on seismic response for chevron panel buckling-restrained braced frames (BRBFs), with hinged steel frames in the braced span, has been carried out. The effects of connection types for frame members outside the braced span on residual deformations of braced frames under rare earthquake actions were mainly examined. The analysis reveals that the maximum inter-story drift of all examined structures, including both 10-story and 30-story structures, are all smaller than the limits of design code under frequent or rare earthquake excitations. The maximum residual inter-story drift ratio of 10-story structures with hinged steel frames outside the braced span under rare earthquake actions exceed 0.005 and these structures develope small inter-story shear forces, large lateral displacements and residual deformations due to their smaller lateral stiffness. When rigid frames are used outside the braced span and especially the rigid frames are designed according to the requirements of dual system, residual deformations of the braced frames can be reduced greatly and the maximum residual inter-story drift ratio is smaller than 0.005. Therefore, it is beneficial to employ rigid frames outside the braced span for multi-story braced steel frames, although it is unnecessary to design the rigid frames according to the requirements of dual system.