Jumbotron’s Thinner Beams Blamed for Collapse at Big ‘A’ : Design: Anaheim hasn’t affixed blame, which could cost someone millions, but engineer cites a key flaw in its supports.

The two main support beams for Anaheim Stadium’s Sony Jumbotron were thinner at a crucial point than designers specified, which caused the beams to collapse during last month’s earthquake, an engineer for Jumbotron said in a report released Tuesday.

Bernard C. Adams, a Garden Grove engineer who helped design the huge scoreboard’s structure for White Way Signs Inc. of Chicago in 1988, said Tuesday that his post-quake examination of the board’s steel support system showed that a key portion of the beams was “significantly smaller” where they joined the stadium’s main superstructure.

He said this flaw, dating from the stadium’s expansion by the construction firm of Skidmore, Owings and Merrill, meant it could not support the 17.5-ton scoreboard’s weight when it began shaking during the Jan. 17 quake. The falling scoreboard crushed or damaged about 1,000 seats in the stadium’s upper deck in left field, and hundreds may have been killed if an event had been taking place during the quake.

“It looks like the frames on the building were not built the way (Skidmore’s) plans showed them,” Adams said. He made his examination the week after the quake and submitted his report to the city on Jan. 24, which released it Tuesday. “The scoreboard should have fared well during the quake, and it would have fared well if this weakness hadn’t been there.”

Adams said the support beams’ flanges, the rims that project from the top and bottom of a beam to give it strength, were supposed to be two inches thick by 18 inches wide throughout the beams’ length. He said he did not make exact measurements of the flanges, but said photos show that the flanges reduced in size significantly as they came into the stadium’s main frame.

“This was terrible,” he said. He said that the change in size added to the stress on the beams. “You go all of a sudden from a large beam to a small beam. This makes it very difficult” for the support system to work.

Skidmore officials were unavailable for comment Tuesday.

City officials said their engineers have not yet issued a report on the quake, so they are not ready to affix blame yet.

But they said it is no surprise that White Way would be pointing its finger at Skidmore. Whoever is found responsible for the collapse could have to pay the city several million dollars in damages. The $125-million stadium has a $6-million deductible on its earthquake insurance. It was the only building to suffer major structural damage within 35 miles.

“I would expect them to be blaming each other,” stadium General Manager Greg Smith said.

Stadium and Anaheim city officials also have said they are considering applying for federal disaster relief aid to repair the Jumbotron.

Skidmore, a San Francisco firm, built the stadium section where the Jumbotron was located in 1979, when the stadium was enlarged to accommodate the Los Angeles Rams.

In 1988, a decision was made to replace the section’s old black-and-white scoreboard with a more modern one that could show color replays.

A Skidmore study before the installation concluded that the old scoreboard’s support structure would be sufficient to handle the new board.

The contract for installing the board went to Sony, which subcontracted the work to White Way.

Adams said White Way had received Skidmore’s old blueprints when it was planning the new board’s installation and trusted that they were correct.

“They did not build (the support system) according to their own plans,” Adams said.

Times Staff Writer Matt Lait contributed to this report.