Effect of Dampers on Seismic Demand of Short Period Structures

Seismic behavior of a single bay frame with diagonal damper that represents short period structures is evaluated in response to the excitation of a set of earthquake records. The frame system is modeled as a Generalized Single Degree of Freedom (GSDOF) system, and is subjected to nine earthquake records representative of the range of dominant site conditions. The relationship between the force modification factor and the global ductility demand for short period structures, in the presence of dampers, tends to approach those of long period ones. Dampers with high damping ratios tend to keep the structural response in the elastic range even for high values of force reductions. Seismic code provisions should be revised to account for short period effect under seismic excitation.