Abstract

Irregularities in the structure can lead to a redistribution of seismic forces and damage in the structure. Irregularity in height of soft-story is one of the irregularities mentioned in various codes. Today, due to the need for open spaces for parking and high-rise commercial buildings, preventing soft story is inevitable. A soft story can occur due to reduced stiffness of a tall story, low strength of the story, and removing the effect of infill walls. The soft-story acts as a fuse and seismic separator which reduces total energy absorption of the structure and energy accumulation on the story. On the other hand, it causes structural failure due to low strength of the story columns and big drift. In the present study, we used 3 models of 5, 10 and 15-story. In the 5-story model, heights of the 1st, 2st, 3st, 4st, 5st floors were increased, respectively. In the 10-story model, heights of the 1st, 3st, 5st, 7st, 9st floors were increased, respectively. In the 15-story model, heights of the 1st, 4st, 7st, 10st, 13st floors were increased, respectively. Heights were increased by 3, 4, 5, and 6 meters, respectively. The total number of models was 60. By performing nonlinear static analysis for these models, we examined the effects of a soft-story level, structure height, and lateral load distribution in terms of parameters such as energy absorption, pushover curve, and story drift. Finally, soft stories were identified and expressed in diagrams.