Residual Seismic Performance of Fire-Damaged Reinforced Concrete Frame Structure with Metallic Yielding Dampers

Structures with varying dampers have been widely designed and constructed for earthquake resistance. However, the residual seismic performance of these damped structures could not be guaranteed after being exposed to a fire because both the primary structure and dampers are vulnerable to high temperatures. The postfire residual seismic performance is an important design index for damped structures whereas no research has been done so far to determine such residual performance. Therefore, this study serves as the first attempt by exploiting the widely constructed RC frame structure with commonly investigated metallic yielding dampers (MYDs) as an example to investigate its residual seismic performance after being exposed to a fire. One story of a RC office building is employed as the single-degree-of-freedom (SDOF) analytical model, and then the mechanical and geometric parameters of MYDs are derived via the design method from the perspective of the uniform damping ratio. In addition, the gas temperature of the natural fire curves is determined according to current European standards, and 16 representative fire scenarios are selected. Moreover, the residual material properties and residual performance of the primary structure as well as MYD are investigated and expressed in mathematical forms. Thereon, the linear forms of the restoring forces of the primary structure and MYD are obtained by utilizing the equivalent linearization method, and the motion-governing and energy-conservation equations are established. Furthermore, the methodology for the parametric analysis is put forward, and the residual seismic performance of the fire-damaged damped structure is derived quantitatively, which is also verified via time-domain analysis with recorded ground motions. The results show that the seismic performance of the SDOF concrete structure with MYD can be reduced significantly by fire damage.