The presented study investigated the improvement of the seismic performance in steel buildings with semi-rigid connections with the Chevron bracing system. The seismic performance of such frames should be improved to prevent possible damages and failures. Accordingly, modelling Chevron bracing system was first done using openness software by adding zipper columns in the semi-rigid steel frames in three 5-, 8- ,and 12-story structures as representatives of low-rise, medium-rise, and high-rise buildings, respectively. 84 semi-rigid frames were analyzed under seven near-fault records using dynamic non-linear time history analysis. The analysis of frames was done for both pinned and ductile connections and the case of removing and adding the zipper column. The results showed that the use of zipper columns in Chevron braces in the steel frames with pinned and semi-rigid connections controls both relative story displacement and maximum lateral story displacement. This effect is significant in frames with ductile connections.
