The Lessons Learned From a Shake-Up : Northridge earthquake may bring about safety advances
There are lessons to be learned from every natural disaster. One that has emerged from the Northridge earthquake came as a complete surprise. Meanwhile, a separate issue involving schoolchildren suggests that luck alone has prevented untold tragedies. There is much to be done on both fronts.
Steel-frame buildings are designed to bend without breaking under enormous forces such as those produced by earthquakes. In a strong temblor, they have long been assumed to be among the safest structures. Well, the Northridge quake is changing that thinking in a way that could be instructive and beneficial.
Cracks were found in the welds of at least 110 steel-frame buildings after the Jan. 17 disaster. That figure represents more than a fourth of all such buildings in the San Fernando Valley and on the Westside. As much as 90% of the connections in those structures cracked. Experts said that they were shocked . . . just the kind of thing you don’t want to hear from experts. The California Seismic Safety Commission went so far as to suggest that officials in the western states suspend building codes and require proof that new steel-frame structures could withstand major temblors. That recommendation was met with great alarm and concern, but there is indeed a different way of viewing the situation.
Not one steel-frame building was or is in danger of collapsing here. In fact, some experts such as UC Berkeley Prof. Abolhassan Astaneh indicate there is more to learn and less to fear from the way those buildings were affected. “The rigid frames simply cracked the stiff welds and made themselves semirigid, and survived the shock with almost no damage to many of the buildings,” Astaneh said.
What’s needed is a prompt assessment of why the connections failed, how much stronger such joints should be and the most economical ways of erecting safe buildings. Studies are taking place at Berkeley and the University of Texas at Austin to improve building designs and determine the status of damaged buildings. Better yet, the California governor’s Office of Emergency Services is funding an $18-million study to develop guidelines for the inspection and repair of steel-frame buildings--just what the City and the County of Los Angeles have been struggling to do in recent months.
The first phase of the study, underwritten by the Federal Emergency Management Agency, will set guidelines for the inspection and repair of buildings damaged in the Northridge quake. This work must proceed apace. With experts predicting that the next major quake here could result in as many as 5,000 deaths and up to $145 billion in damage, it’s time to learn all that we can about this unexpected chink in our seismic armor.
Schools in quake-prone areas present another set of problems, including the use of suspended ceilings and flimsy light fixtures that could fall in a temblor. And school systems have been ineffective in ensuring that every school comply with safety procedures and requirements as routine as having emergency kits and water on campuses. None of the last 10 major California quakes occurred during school hours. We can no longer afford to depend on such good fortune.