STUDY OF THE BEHAVIOR OF ZIPPER BRACED FRAMES

Due to the buckling of compressive brace in inverted-chevron braced frames, an unbalanced vertical force has to be applied on the intersection of braces and above beam, which will make an oversized displacement at the beam mid-span. This disparate force results in a strong beam design which is not proportionate to other members. Also, buckling of the compressive brace, results in a localization of the failure and loss of the lateral resistance. One of the ways to overcome this problem is to use a vertical structural element at the beam mid-span from the second to the stories above, called zipper strut. In order to evaluate the behavior of this new system, known as the zipper braced frame, some in-plane frames with zipper struts was modeled in OpenSees, along with chevron frame system. These models were analyzed under pushover conditions and their ductility, drift and internal forces of the members were compared with each other.