Comparison of seismic behavior of chevron and suspended-zipper braced frames under near-fault ground motion

Chevron braced frame (inverted V shaped) is one of the common lateral load resisting systems in the steel structures. Although this system has high stiffness and resistance, it exhibits poor post-buckling behavior. Following the brace buckling on a story, an unbalanced vertical force enters to the mid-span of the beam which causing failure on that story and finally leading to the destruction of the structure. To avoid this condition, vertical elements known as “zipper columns” are used to transfer the unbalanced force to the upper stories and the hat truss is attached in the top story. This modified system called “suspended-zipper braced frame”. The present paper aims to compare the seismic behavior of the chevron and suspended-zipper braced frames under near fault earthquakes. For this purpose, nonlinear time history dynamic analyses were conducted on the chevron and suspended-zipper braced frames with 3, 6, 9 and 15 stories utilizing commercial general purpose nonlinear program. The selected models were designed in accordance with Iran’s steel provision and Iranian standard 2800. Based on the results, it is observed that the dynamic behavior of the suspended-zipper frames can be better than the chevron frames in drift controlling, maximum displacement of stories and response history of roof displacement under a specific earthquake. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG.