Full-Scale Experimental Testing and Postfracture Simulations of Cast-Steel Yielding Connectors

摘要

The cast-steel yielding connector (YC) is a yielding fuse device designed to dissipate earthquake energy through inelastic deformations in specially designed distributed yielding regions, while ensuring primarily elastic behavior elsewhere in the structure. The YC exhibits a stable, symmetric hysteretic response with a characteristic postyield stiffness increase due to a combination of friction and second-order geometric effects. The ultimate limit state of the YC is governed by the ultralow-cycle fatigue (ULCF) fracture of the yielding sections, where fracture begins after a relatively low number of large inelastic cycles, followed by a slow strength degradation. This paper presents tests and finite-element analyses of small-scale coupons and full-scale tests of a variety of YCs. Detailed finite-element models of YCs are developed and a novel crack propagation simulation scheme is proposed to numeri-cally simulate its ductile fracture initiation, propagation, and associated degradation and regaining of strength due to crack opening and closing. This simulation scheme is validated against 14 small-scale coupon tests and 11 full-scale YC tests. Full-scale test results and the validated model are then used to investigate the influence of in-plane rotation and out-of-plane demands on the overall performance of YC in a nonbuckling concentrically braced frame configuration. DOI: 10.1061/(ASCE)ST.1943-541X.0002844. (c) 2020 American Society of Civil Engineers.