EXPERIMENTAL STUDY ON MECHANICAL PROPERTY OF Y-ECCENTRICALLY BRACED COMPOSITE FRAME WITH REPLACEABLE LINK

A Y-eccentric brace composite frame with replaceable link (Y-V-EBCF for short) was designed as test specimen to investigate the mechanical property of Y-V-EBCF in this study. Especially, the replaceable link was made of low-yield point steel and connected to peripheral members through high-strength bolts. The cyclic loading tests of Y-V-EBCF specimen and the specimen removing damaged link were carried out. The failure mode, load-displacement curve, and residual drift were obtained. The results indicate that the structure has a stable property of hysteresis and excellent energy dissipation before the link fails. After removing the damaged link, the structure enables to return to the undeformed initial shape under the unbalanced internal force. The residual drift of specimen (0.002 rad) is much less than that of specification (0.005 rad) and the maximum replaceable residual angle (0.0023 rad), and the load-displacement curve of the residual specimen is still plump. The two facts indicate that Y-V-EBCF has favourable resilience. The current design provision according to ANSI/AISC360-16 can be applied to calculate the strength of shear links made of low-yield point steel accurately, but the over-strength factor should be increased to 3.0 to prevent the failure of peripheral member. The stiffness and strength of Y-V-EBCF can be calculated by the linear superposition of the link part and the composite part. Additionally, the concrete slab of the middle segment of the primary beam is cracked because of the added bending moment imposed by the shear link of Y-V-EBCF, and a formula is proposed to calculate the crack width at the middle of the primary beam.