Abstract

The Christchurch Earthquake of 22nd February, 2011 revealed the first field fractures observed worldwide in Eccentrically Braced Frames (EBFs). These fractures are surprising because they occurred in the “fuse” region of a system that is otherwise considered highly ductile. The fractures have global implications for seismic design, since design standards in New Zealand are as stringent as those in the United States, Europe, Japan, and elsewhere. The seminar will present a comprehensive study that examines these fractures forensically, with the objective of providing an understanding of the various factors that contributed to fracture. The study is based on samples of the fractured links that were salvaged from the fractured frames. The study spanned several scales, scientific methods, and aspects of behavior including: (1) material testing (2) frame simulations of the entire structure (3) continuum finite element simulations of the failed regions, and (4) micromechanics-based models for simulating fracture. When integrated, findings from these various research components provide a compelling, yet nuanced understanding of the EBF fractures. Perhaps more importantly, the study features an “end-to-end” simulation of a structural system across various scales, with the benefit of measured material data and observed structural response. Thus, it provides a unique opportunity to examine the advances and the challenges in hi-fidelity simulation of fracture in structures. The seminar will address these methodological challenges in addition to the practical aspects of the EBF fracture.