This paper describes the development of a new type of friction damper for unbonded post-tensioned precast concrete building moment frame structures in seismic regions. Previous research has shown that these structures have desirable seismic characteristics such as a self-centering capability and an ability to undergo large nonlinear lateral displacements with little damage; however, displacements during an earthquake may be larger than acceptable. To reduce displacements, the proposed friction dampers are placed at selected beam-column joints, and dissipation of energy occurs through joint gap opening. Large scale beam-column subassemblies with and without dampers were tested under reversed cyclic loading. Results show that the dampers can provide a significant amount of supplemental energy dissipation at the beam ends, while the self-centering capability of the structure is preserved.
