buckling of compression braces during earthquakes in Chevron Braced Frames causes a large unbalanced vertical force in the midpoint of the braced beam and reduces the lateral capacity of the structure. Adding a zipper column between midpoints of braced beams can lead to the transfer of the unbalanced force to the top story and result in the distribution of damage over the structure’s height instead of one special story. To evaluate this system called Suspended Zipper-Braced Frame against a wide range of earthquakes, a probabilistic assessment of collapse risk proposed in FEMA P695 methodology was used. Accordingly, several buildings with various heights were designed in Seismic Design Category Dmax, as per ASCE 7-05. Static pushover and incremental dynamic analyses were conducted on nonlinear modeling of frames in consideration of connection details to obtain collapse margin ratios. These ratios were compared with predefined limits suggested in the methodology. The results indicate that the response modification factor recommended in the code provisions for Special Concentrically Braced Frames causes a high value of collapse margin ratios for Suspended Zipper-Braced Frames against a wide range of earthquakes so that they can pass all the acceptance check process of FEMAP695 methodology.

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