Evaluation of site effects on the seismic performance of a friction-damped steel IMF under near-fault earthquakes

The local site conditions and the geological properties of soil materials on which buildings are constructed might play a pivotal role in changing the characteristics of input seismic ground motions, and subsequently affect the seismic performance of the structures. These effects should be considered in the seismic evaluation of structures, especially those equipped with damping devices. As a matter of fact, these devices are designed to increase the energy dissipation capacity of the buildings through certain inelastic mechanisms, which are highly dependent on the input ground motions. Friction dampers are one of the cost-efficient controlling devices in which whose performance mostly depends on the story displacements. Hence, the variation in seismic excitations caused by the local site effects might have an impact on how they mitigate the earthquake hazard in addition to their efficiency. Shedding light on the above facts, this paper evaluates the influence of site effects on the seismic performance of a 10-story intermediate friction-damped steel moment frame under near-field excitations. Nonlinear time-history analyses are done using ten ground motions, which have been originally recorded at bedrock, while variation in their properties is calculated by passing them through a soil profile, which is modelled using the equivalent linear method. The result indicates that considering the site soil effects has a major consequence on ground motions as well as the performance of dampers insofar as it leads to a rise in the amount of input energy and the story drifts. Nevertheless, the seismic performance of the dampers remain quite efficient and reliable.