Seismic Design of Friction-Damped Precast Concrete Frame Structures

This paper presents the seismic design of unbonded posttensioned precast concrete frame structures that use friction dampers for supplemental energy dissipation. A procedure is described to determine the friction damper slip forces and posttensioning steel areas needed to satisfy prescribed design lateral strength and energy dissipation requirements for a trial frame with given geometry, beam and column member dimensions, and selected damper distribution. The proposed design procedure assumes that the lateral strength requirements for the frame have been obtained from a linear elastic analysis of the structure under equivalent lateral forces. Nonlinear reversed-cyclic analyses of friction-damped precast concrete beam-column subassemblies and multistory frame structures under lateral loads are conducted to critically evaluate the design procedure and to identify areas where improvement may be needed. The analytical results show that friction-damped precast frames can be designed to achieve significant energy dissipation levels while maintaining a large level of self-centering capability due to the posttensioning force.