Investigation of Earthquake Significant Duration on the Seismic Performance of Adjacent Steel Structures in Near-Source

According to the recent Earthquake records, the earthquake duration is longer in some areas, resulting into more structural damage. One of the important factors in reducing earthquake damages is the separation gap between two adjacent structures. This case study investigated the effect of significant duration of the earthquake on two adjacent steel moment-resisting structures with different heights and near to active fault. The pounding between pairs of three 3, 6 and 9-story steel moment frames was evaluated using a nonlinear time history analysis method considering the reduced stiffness and strength. The results showed that for the intended type 3-soil, the risk of pounding and collapse amplification among the 3- and 6-story buildings are higher than others. This is due to the necessity of the Iranian standard 2800 to calculate the separation gap by the nonlinear methods for the buildings with height more than 8 stories. Also, the analysis of the significant duration of the applied earthquakes demonstrated that this parameter is a determining and effective factor in the pounding of structures, especially the adjacent buildings with defferent heights. It is noteworthy all of the analysis was done by 9 earthquake records. This study recommended using the nonlinear method to calculate separation gap while designing two adjacent steel moment-resisting structures with different heights in the near-field area and on the soft soil.