Adel Ghorbani asl - Civil Engineering Expert, Organization for Development, Renovation and Equipping Schools of Iran,
Maryam parvaresh, - Department Earthquake Engineering, University of Mohaghegh Ardabili, Ardabil, Iran,
Amir Lamei Javan - Student in Structural Engineering, University of Mohaghegh Ardabili, Ardabil, Iran,

In this paper, the seismic behavior of two-dimensional steel frames without a bracing system with semi-rigid connections and different combinations of rigid and semi-rigid connections has been studied under near-fault accelerograms and their seismic performance has been compared with that of the frame with rigid connections. A group of several three-span three-story steel frames (as representatives of low-rise frames) with rigid, semi-rigid, and different combinations of rigid and semi-rigid connections (۲۶ cases) were analyzed under four near-fault accelerograms based on soil and site classifications. Non-linear dynamic time history analysis using OPENSEES software was done and the dynamic response of the group was compared to the failure level of the frame. This evaluation showed that at the failure level, the maximum relative story displacement was on the second story of the fully-rigid frame. As the fully-rigid connections are changed to the semi-rigid ones, the maximum relative story displacement increases, and the base shear decreases at the first-story level. On the other hand, the maximum relative story displacement decreases, and the base shear increases as the connections are replaced with semi-rigid ones at the upper-story level. Depending on the arrangement and number of semi-rigid connections, the frame can be found with an arrangement of semi-rigid connections in which the base shear and maximum relative story displacement are reduced in comparison to the rigid frame showing a desirable performance.

Seismic behavior, Steel frames, Semi-rigid connections, Non-linear, Failure level