No abstract

Direct displacement–based design (DDBD) methodologies simplify the estimation of the seismic deformation demands of a nonlinear system by replacing it with an equivalent linear system that is characterized by an effective stiffness and equivalent damping ratio (EDR). The calculated EDR for flag-shaped hysteresis relationships vary greatly among existing DDBD methodologies, and these methodologies display a strong bias according to the shape of the ground-motion response spectrum. In the work reported here, the limitations of existing methods are demonstrated for three sets of ground-motions: a set of far-field ground-motions, a set of near-field ground-motions, and a set of physics-based simulated ground-motions that account for the effects of a deep sedimentary basin. The effect of spectral shape can be quantified by a new measure of spectral shape that is based on the spectral displacement ordinates between the system’s initial and equivalent periods. To address the limitations of existing methodologies, a new equation for calculating EDR was developed based on numerous nonlinear history analyses for all three sets of ground-motions and for a wide range of systems with flag-shaped hysteresis. In comparison with existing equations, the proposed equation for calculating EDR improves the accuracy of the DDBD methodology by lowering the bias and dispersion of the ratio between the displacement calculated by nonlinear analysis and the displacement calculated with the equivalent linear system. The usage of the new EDR equation in DDBD requires iteration, but neither numerical modeling nor analysis is needed. Specific steps of the application are demonstrated for a system with a flag-shaped hysteresis.

Summary The increasing expectation of structures capable of fulfilling the requirements of minimizing post‐earthquake repair or re‐occupancy has led to the emergence of damage‐control technologies. In recent years, self‐centering precast concrete wall systems that are characterized by low damage as well as full prefabrication have become a popular topic. Previous research has shown that the system is not only capable to reduce the construction time but also has the characteristics of small residual displacement and quick restoration of normal service function after a major earthquake event. Nevertheless, there is still much to be studied for high‐rise buildings and practical engineering applications. This paper introduces the process of self‐centering precast concrete wall systems from conceptual design to detailing and construction aspects of a 10‐story case study building. Specifically, the hybrid type of unbonded post‐tensioned wall is adopted with mild steel functioning as the energy‐dissipating component. The design and construction of mild steel take into account the requirements of both building function and replaceability. In addition, the lateral resisting system is decoupled from the gravity system using isolated joints for wall‐to‐floor connection. Various factors such as higher mode effects, torsional effects, and wind loads are considered in the design process in order to achieve the overall high performance of the structure. Finally, the numerical model of the designed structure is established and analyzed under both static and dynamic loading. Results show that the self‐centering wall structure studied in this paper has satisfactory seismic performance, i.e., each component and joint can work to achieve the function as expected, and has broad engineering application prospects in the future.