New Stadium to Meet Standards for Earthquakes, Engineer Says

Article excerpt

ST. LOUIS' NEW domed stadium is almost ready for crunching tackles and deafening applause. But will it be ready for shaking from a major earthquake?

Yes, says the stadium's structural engineer.

The stadium's builders followed current building codes that require all major structures be built to resist earthquakes, said the engineer, Jim Adkins of Hellmuth, Obata & Kassabaum Inc. Its design was approved by city building inspectors.

"Particularly because it's a public facility with large numbers of people, the stadium has a higher level of seismic design," Adkins said last week. "We consider it quite sound from a seismic perspective."

The St. Louis region is increasingly taking the "seismic perspective," experts here said last week. They said reports about Tuesday's earthquake in Japan will deepen concerns about this region's own earthquake threat - from the New Madrid Fault.

The fault winds underground for more than 100 miles from northeastern Arkansas, through the Missouri Bootheel and into the southern tip of Illinois. It is famous for erupting with thousands of earthquakes in 1811-12, including at least three measuring above 8.0 on the Richter scale.

The chances of a quake measuring 8 on the Richter scale are slim any time in the near future, experts say. But there's a 50-50 chance of a quake measuring 6 over the next 15 years and a 90 percent chance over 50 years.

The $260 million football stadium is the latest major public facility in St. Louis to be built under the most recent of a continuing series of new building codes - this one requiring earthquake resistance. Other facilities built with earthquakes in mind include the Kiel Center and the St. Louis Science Center.

The stadium, which will seat between 65,000 and 70,000 for football, is designed to withstand the forces of a magnitude 7.6 earthquake in the New Madrid Fault, Adkins said. Among the earthquake-damping traits the stadium has that others don't:

Stronger connections between beams.

Heavier columns, foundation, bracing walls and diagonal bracing beams.

Wider joints than those normally used to handle building movement.

Extra bracing for suspended pipes and mechanical equipment so they do not break loose and swing free.

A roof designed to slide back and forth up to 2 feet during a quake.

"Our purpose is to maintain stability of the structure until the occupants can safely leave," Adkins said. "Minor damage" may occur, including cracks in walls and damage to lightweight parts of the building.

Figures on the added cost of the earthquake design aren't available, he said. But national studies suggest that such strengthening generally adds about 1 percent to the cost of a structure. …