The lessons of Chile earthquake to California building code
Since the Chile earthquake, many U.S. engineers have visited Santiago and other affected cities to study the failures and successes of building codes here; Chile is of particular interest to American engineers because it employs similar building codes to those in California and also has widespread use of reinforced concrete; one observation from Chile’s earthquake that could find its way into U.S. building code concerns confining reinforcement; confining reinforcement is meant to keep vertical bars from bucking, but the design proved insufficient in Chile; one solution: requiring confining reinforcement along a greater length of the wall
In the Santiago district of Maipu, passersby kept a safe distance from a broken four-story apartment complex. Mehmet Celebi, a research engineers, wanted inside. Celebi had come here from the office of the U.S. Geological Survey in Menlo Park, California, to study concrete structures damaged by the massive 8.8-magnitude earthquake that rattled Chile on 27 February. The building, as it leaned precariously, had become one of the now-iconic images of havoc caused by the quake.
Celebi pored over the building, looking for the design failures that caused walls at the base of the building to crumble. “This is what you call ‘soft story,’” Celebi said, using the term to describe buildings that are weaker at the lower level than up top. When the quake hit, the largest load came down on the weakest part of the structure and the walls buckled.
“I think we have observed this is crushing,” Celebi concluded, pointing to twisted rebar spilling out from the wall’s interior. “This is a prize from an engineering point of view.”
The Christian Science Monitor’s Aaron Nelsen writes that in the wake of the fifth-largest earthquake ever registered, dozens of scientists such as Celebi are flocking to Chile better to understand how structures perform when pushed to the limit. The Earthquake Engineering Research Institute in Oakland, California, sent more than thirty researchers to record data from Chile’s homes, hospitals, bridges, and apartment buildings.
A unique opportunity in Chile
Structural engineers typically work as consultants to the architect. The architect designs the look, function, and spaces in the building, while the structural engineer designs the skeleton that ensures the building will withstand wind, earthquakes, and other forces. This is done according to codes often based on computer simulations. When an earthquake occurs, it provides a unique opportunity to study a living laboratory.
“It’s fascinating to see the kinds of things that we do calculations on every day do occasionally get put to their ultimate test,” says Joe Maffei, a structural engineer and principal with Rutherford & Chekene in San Francisco, who made a recent trip to Chile to study the behavior of concrete structures in Santiago, two coastal cities, and Concepción, the city nearest the epicenter. “This is an opportunity to see if we are applying the science right in building codes.”
Chile is of particular interest to American engineers. It employs similar building codes to those in California and also has widespread use of reinforced
