Abstract
Two one-third-scale three-story models of special inverted-V-braced frames with zipper struts were tested under quasistatic cyclic loads. Zipper frames utilize a vertical element at the intersection of chevron braces and floor beams to distribute the unbalanced vertical forces due to brace buckling. Two ground motions representative of a far-field (Chile 1985) and a near-field earthquake (Kobe 1995) were selected for the tests. Two tests with two different amplitudes of the 1985 Chile earthquake were conducted on one frame; three tests with three different amplitudes of the 1995 Kobe record on the other. For each specimen, a pre-experiment numerical model was used to generate the three floor displacement histories that were applied to the test frame. Comparison of the results for the hysteretic behavior of the braces, zipper struts, and overall frame validated the partial-height zipper mechanism envisioned in proportioning the specimens. The frames showed good dissipating-energy capacity and large deformation ductilities without significant strength losses. Moreover, they remained stable even after fracture of some braces occurred and showed significant residual strength.
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