Panel Wants Steel-Frame Buildings Codes Altered : Ordinance: Temporary measure would change requirements for beam-to-column connections.
City building officials recommended Tuesday that the Los Angeles City Council enact a temporary ordinance to alter the way steel-frame buildings are constructed.
The ordinance would change part of the current building code section governing requirements for beam-to-column connections in steel-frame buildings--the major source of problems in those types of buildings that were damaged during the quake.
“It’s been found that the connection doesn’t perform adequately and we don’t want any additional buildings to be built with this connection,” said Richard Holguin, assistant chief of the city’s Building Bureau.
The request for an emergency design standard, expected to go before the full council next week, was made Tuesday during a special meeting of the Ad Hoc Committee on Earthquake Recovery and was prompted by post-quake inspections that found serious problems in the welded connections of steel-frame buildings.
At least 110 steel-frame commercial buildings--most of them in the Valley or on the Westside--were damaged during the quake. Another 900 such buildings could be in danger if another major quake hits Los Angeles, according to the Los Angeles Department of Building and Safety.
“Everybody knows at this point that (the current code section) doesn’t perform to the expectations of the engineering community,” Holguin said.
Typically in steel-frame buildings, horizontal beams and vertical columns are welded together. In some buildings, these connections broke or cracked during the quake.
The subsection of the code that would be suspended by the temporary ordinance currently allows builders of steel-frame structures to build without conducting involved studies and tests to prove that their connections are sound.
Holguin described the code section as “sort of a cookbook approach to the design of that connection. . . . It told you specifically, ‘If you do this and this, you don’t have to go into an elaborate test procedure to show that the design will work.’ ”
The temporary ordinance would require builders to meet more detailed design requirements and perform a more in-depth study of the connections, Holguin said.
“They will have to . . . prove to the department that the connection will work, based on design, based on tests, or both,” he said.
Trailer Martin, a private structural engineer, spoke before the committee and showed photographs of welded joints that cracked during the quake. Some cracks were three-eighths of an inch long.
Of the 30 steel-frame buildings Martin has inspected in West Los Angeles and in the Valley, he said 21 “have serious problems.”
“It’s widespread and it needs to be addressed,” he said.
The temporary ordinance would only apply to new buildings that have not previously been issued permits and not to existing buildings or those being repaired, Holguin said. It would remain in effect for a maximum of one year, but would be followed by a proposal for permanent changes, Holguin said.
“The final answer will depend on some of the testing taking place,” he said.
Currently, tests on steel-frame buildings are being conducted at UC Berkeley and at the University of Texas, Austin.