Another Defect in Interchange Bridges Found

An independent analysis of the Orange Crush interchange has revealed a potentially serious defect: The steel bars installed to keep bridges intact during an earthquake are too brittle, according to the state senator who commissioned the study.

State Sen. Joe Dunn (D-Santa Ana) cautioned Thursday that the results of the analysis were preliminary. The bridges are strong enough for the wear and tear of everyday traffic, Caltrans officials said.

But metals experts who examined samples taken from the bridges that join the Santa Ana, Garden Grove and Orange freeways found that the problems extend beyond defective welds that Caltrans discovered last year.

“There is a different problem, and a potentially more serious one,” Dunn said. “It appears the [bars] are brittle. This is an issue, a serious issue, that we need to find a solution for as soon as possible.”

The state will quickly begin pulling the steel bars from the Orange Crush bridges and see if they match the conclusions of the independent tests conducted by a Menlo Park, Calif., company, which did the work free of charge. Dunn asked the company to analyze the samples as part of a legislative inquiry into the $85-million construction of the Orange Crush.

Caltrans already had planned to pull the faulty welds from the interchange this month and no traffic delays are expected because most of the work is to be done at night.

Caltrans’ chief engineer in Sacramento downplayed the new findings Thursday night.

“We’ll have to check it out, but I don’t think it’s going to be much of a problem,” said James Roberts, the No. 3 official at the agency. “If there is a problem with the steel, then we’ll replace it.”

Roberts said three other interchanges in the state have the same type of steel supports: the portion of the Santa Monica Freeway that was rebuilt after the 1994 Northridge earthquake; the intersection of the Golden State and Antelope Valley freeways near Santa Clarita; and the bridges in San Diego that connect Interstates 8 and 805. The Santa Monica and San Diego bridges have already been tested and no problems were found while workers are still testing steel bars in the Santa Clarita interchange, Roberts said.

The steel bars, called hoops, are part of the bridge columns and act like a basket designed to catch concrete rubble in the event of an earthquake, keeping the column stable and upright. If the hoops snap during a temblor, the columns might collapse.

“It is a major concern,” said state Assemblyman Lou Correa (D-Anaheim). “Now we are beginning to question whether this work to retrofit for earthquakes was successful. Exactly how much stress can these bridges hold? How bad is the problem?”

Although four interchanges use the hoop technology, the columns in hundreds of other older bridges throughout the state were wrapped with steel casings--part of a $4-billion seismic retrofit project. Caltrans believes these older bridges are sufficiently reinforced.

The Century Freeway and other new structures use an updated technology wherein the steel hoops are interconnected to provide even more strength.

The seismic retrofitting program in the state dates back about 30 years when California first revised its bridge standards to deal with the likelihood of earthquakes. The $4-billion effort, begun a decade ago, involved about 2,200 bridges statewide, according to Caltrans.

But even as Caltrans hurried to build and seismically retrofit bridges across the state, the agency had just one overworked inspector sifting through hundreds of thousands of X-rays of critical welded joints, Caltrans acknowledged last year. The Orange Crush and the Santa Clarita interchange are the last two in the state to be finished.

*

Times staff writer Megan Garvey contributed to this report.