Steel-Frame Design Guidelines Disputed

Acting Wednesday on the 95th anniversary of the San Francisco earthquake of 1906, experts from the Federal Emergency Management Agency called for new quake-resistant design and construction guidelines for steel-frame buildings, but immediately encountered some official resistance.

FEMA recommended new ways of connecting the beams in steel frames as well as new construction procedures that the agency believes will help limit the kind of cracking of frames noted in at least 30 buildings in the 1994 Northridge earthquake. The recommendations go beyond steps Los Angeles took after Northridge, which required new weld metals.

But a ranking member of the Los Angeles city Building and Safety Department said Wednesday that for now it is willing to allow builders in Los Angeles to use only two of nine types of new welding connections that FEMA has called for.

Nick Delli Quadri, assistant director of the department’s bureau of engineering, said that the other types of recommended welding connections have not been adequately tested.

Delli Quadri added, “These are only guidelines. They are not compulsory, not part of the building code yet.” And, he said, they are being questioned by some in the structural engineering community.

However, the head of the Structural Engineers Assn. of Northern California, James O. Malley, who had worked with FEMA on a six-year, $12-million study of the cracking of steel-frame buildings, joined in advocating the guidelines.

Malley acknowledged that some members of the group’s Southern California branch were resisting them. “They haven’t read all 12,000 pages of our study yet,” he quipped.

Officials of FEMA, which paid for the study, said the guidelines are primarily designed to reduce stress at steel frame connection points by developing, among others, “dog-bone”-shaped connections that diffuse the stress on individual beams. They are available to builders from fabrication shops that do custom design work.

FEMA documents released in Washington, D.C., emphasized that the guidelines had been developed in cooperation with the structural engineers, and noted that it was up to government entities and professional associations to decide whether to place them in building codes.

Malley and another engineer participating in the news conference, Ronald O. Hamburger, estimated that the guidelines, if followed, would add 2% to 3% to the cost of new buildings.

But they said the cost of changing connections in existing buildings would be much higher--in most cases, as high as the cost of repairing the damage the buildings would suffer in a strong earthquake.

Accordingly, Malley and Hamburger said they doubted that many builders would agree to follow the guidelines in altering existing buildings.

Delli Quadri, the Los Angeles building official, emphasized that in the wake of the Northridge quake, Los Angeles had directed that new kinds of weld metal be used in steel frame connections and that 200 possibly compromised buildings be inspected for damage.

He said the Los Angeles Building and Safety Department is willing to allow the proposed new dog-bone and bolted cover-plate connections listed in the guidelines to be used because they are the only proposed FEMA improvements that have been adequately tested.

Delli Quadri added that the builders are not being required to use any of the guidelines.

In the Northridge quake, no steel-frame buildings collapsed. But, a year later, an earthquake in Kobe, Japan, destroyed 50 mid-size steel-frame buildings, leading U.S. officials to believe that additional safeguards were advisable.