Learning From the Northridge Earthquake

Northridge Aftermath: Aftershocks Continue, ENR, January 26, 2004, dicusses the impact of the 1994 Northridge Earthquake on structural design practice even today, 10 years later.

One of the most interesting aspects of this earthquake event was the unexpected discovery of failed steel beam to column connections in 100 or more buildings involved in the earthquake. These failures occurred in buildings of diverse ages, and in many cases, in locales that experienced only mild ground movements during the quake. These unexpected, brittle connection failures have resulted in major rethinking of the design of steel connections in welded moment-resisting steel frames.

This article also discusses areas where some experts argue improvements are still needed. These include improved dialog between structural engineers and earth scientists, as well as attending to older unreinforced masonry and non-ductile reinforced concrete structures.

In the aftermath of the unexpected framing failures, a joint venture of the Structural Engineers Association of California, the Applied Technology Council, and the California Universities for Research in Earthquake Engineering, aka SAC was formed with the goal of "investigating the damage to welded steel moment frame buildings in the 1994 Northridge earthquake and developing repair techniques and new design approaches to minimize damage to steel moment frame buildings in future earthquakes". For those wishing to know more on this topic, portions of SAC's Interim Guidelines also make interesting reading.