Seismic lateral displacement analysis and design of an earthquake-resilient dual wall-frame system

Traditional reinforced concrete shear walls are both prone to damage during earthquakes and difficult to repair after an earthquake. Accordingly, two replaceable buckling-restrained braces (BRBs) are installed at the base of a hinged wall (HW) to form an earthquake-resilient shear wall (HW with BRBs at the base, HWBB). This paper focuses on the seismic analysis and the design of a dual system with an HWBB and a moment-resisting frame (HWBBF). An elastic lateral displacement analysis is conducted for the HWBBFs based on an equivalent continuous model, which consists of a flexural beam with a rotational spring at the base and a shear beam. The strength and stiffness demand formulas of the HW when the frame enters the inelastic stage are approximated based on the results of the elastic analysis. Based on the provided inelastic formulas, an elastic displacement spectrum-based design procedure is presented for HWBBFs to directly determine the sectional area of the BRBs, the required strength and stiffness of the HW. As an example, a 6-story HWBBF is designed using the proposed procedure, and a series of nonlinear response history analyses (NRHAs) are used to validate the procedure and inelastic formulas. The example effectively illustrates the errors associated with the target roof displacement and the formulaic HW demands compared to the corresponding NRHA results, respectively.