Parametric studies of soft-storey structures with upper toggle-brace-damper systems

Soft-storey mechanism is characterized by a sudden reduction of lateral stiffness in one or more levels of a structure. Soft-storey is often observed in the ground level due to the absence of wall or cladding. With recent develop of energy dissipation systems, soft-storey mechanism can be improved by addition of a damper-brace assembly. In particular, this research presents a parameter study on configuration of toggle-brace-damper as a passive energy dissipation system in retrofitting soft-storey structure. Governing equations including the magnification factor and lateral stiffness contributed by a toggle-damper-brace are formulated. The relationship between magnification factor and the geometry of structure are determined. The optimal geometrical design of toggle-brace mechanism is discussed. Nonlinear time history analyses are carried out on selected brace configurations in OPENSEES. Results are presented in this study provide an insight into the preliminary selection of base structure geometric design. In particular, a comprehensive economical design steps has been finally performed.