The Northridge earthquake struck the greater Los Angeles area during the early morning hours of January 17, 1994. The earthquake was responsible for approximately 60 deaths, more than 9,000 injuries, and an estimated $20 billion in damages. Significant ground shaking occurred over a wide area and exceeded design code values in many locations. Numerically, most of the damage was to wood-frame residences, but upwards of 200 concrete buildings were red-tagged. The Northridge earthquake was the first big test of pre-1980 concrete buildings and post-1980 buildings designed using updated code provisions following the 1971 San Fernando earthquake. …