Nonlinear Dynamic Behavior of Eccentric Braced Steel Frames Under the Near-Fault Earthquakes

In this research are investigated the behavior of EBF frames subject to far-fault and near-fault earthquakes. For this purpose two dimensional models of EBF frames with 3,6 and 12 stories and considering 3 different eccentricity/length ratio of (0.5,0.7,0.9) for each frame are modeled. Nonlinear dynamic behavior of EBF frames are investigated Under 4 pairs of far and near-fault records. Relative displacement, story displacement, coefficient, base shear and ductility-demand are calculated and compared for near and far fault earthquakes.The research findings are: Ductility-demands and displacement-demands are larger for near-fault than those of far-fault. Recommended magnification factor for base shear in the 3, 6, and 12 story frames are 1.65, 1.64 and 1.89 respectively. Magnification factor of base shear is increased with an increase in structure's period. Hysteresis graphs show that more energy is applied in the near-fault earthquake with respect to far-fault earthquake.