Halabian - Assistant Professor, Faculty of Civil Engineering, Isfahan University of Technology, Isfahan, Iran
Doostmohammadi - Graduate Research Assistant, Faculty of Civil Engineering, Isfahan University of Technology, Isfahan, Iran

Near-fault ground motions are characterized by a large high-energy pulse. These motions, which are particular to the forward direction, are mostly oriented in a direction perpendicular to the fault, causing the fault-normal component of the motion to be more severe than the fault parallel component. The near fault ground motions come in large varieties and impose high demands on structures compared to “ordinary” ground motions. The main objective of this paper is to acquire the knowledge on the effects of near-fault ground motions on the response of R/C frame structures. To achieve this goal a set of generic R/C frame structures with different stories are developed. The frame models are designed according to the “Weak beam- Strong column” strategy, and members strength are tuned such that simultaneous yielding occurs at the beam ends (and the column bases) under the SRSS shear force pattern. Performing some nonlinear time history analyses, the results showed that the near fault earthquake presents much more damage than those far-field earthquakes. The inelastic dynamic responses to both near-fault records and basic pulses demonstrated that structures with a fundamental period greater than the pulse period respond very differently than shorter period structures. For the frame structures with a period longer than the pulse period, the distribution of story shear forces over the height of the structure differ significantly from the design distribution and causes early yielding in the middle stories. But for the frame structures with a period shorter than the pulse period the distribution of story shear forces over the height of the structure is relatively close to the design distribution and early yielding in bottom stories is expected.