Detailed Database of Tall Pre-Northridge Steel Moment Frames for Earthquake Performance Evaluations

This projects presents a detailed database of 89 tall steel moment frame buildings representative of the construction practices in the western U.S. before the 1994 Northridge earthquake. This database contains all details that affect the structural performance of steel moment frames, including frame geometry in both directions, member cross-section sizes, and gravity system characteristics. This database also captures irregularities that might impact seismic response, such as podiums, setbacks, mass concentrations (MEP floors), interrupted column lines, and atriums. Fourteen buildings were built before 1960 and have moment frames with riveted connections, while the remaining 75 have welded flange connections like those that suffered brittle fracture during the 1994 Northridge earthquake. The database includes 48 space frame, 27 perimeter frame, and 14 intermediate frame buildings. We created an automatic workflow to diagnose structural behavior and generate realistic linear and nonlinear models in OpenSees for 41 buildings that had enough information out of the 89 in the database. The design diagnostics show that most of these buildings fulfill modern-code strength requirements, but many lack lateral stiffness to satisfy current drift limits. In addition, some buildings have weak column designs or weak panel zones, which could lead to non-ductile collapse mechanisms. These vulnerabilities are loosely correlated to the design era of the frames, indicating that generic analyses based on the completion year have limited applicability. This database, associated structural models, and processing scripts are shared within a workflow that encourages collaboration and extension from the engineering community with the ultimate goal of creating solid data for simulations that could reliably inform risk mitigation strategies on a regional scale.