11.21: Experimental evaluation and explicit fracture simulations of stainless steel seismic dampers

Abstract

Seismic dampers with high post-yield stiffness were recently proposed by the authors as the main energy dissipative system in a seismic-resistant steel frame. The dampers are hourglass-shaped pins made of duplex stainless steel and their high post-yield stiffness significantly reduced the residual drifts of the frame after the design earthquake. This work evaluates the cyclic behaviour of the proposed dampers both experimentally and numerically. Two different geometries of full-scale prototype dampers were tested under various standard and random cyclic loading protocols in a configuration that reproduced the damper-brace connection in the actual steel frame. The results of fourteen tests showed that the proposed dampers possess excellent hysteresis and fracture capacity. Following the tests, explicit numerical simulations were carried out using the Abaqus software. Geometry-independent fracture criteria were calibrated using the results of monotonic and cyclic tests on coupon specimens made of duplex stainless steel, and explicitly included in the numerical simulations of the dampers. The finite element models are able to accurately capture the initiation and evolution of fracture in the prototype dampers subjected to both standard and random cyclic loading histories. The results can be used to calibrate reliable macro-models for seismic collapse simulations of the proposed frame.