Caltrans Refused to Use Weld Alternative

When contractors asked to use mechanical couplers instead of old-fashioned welds in several Southland bridge projects nearly five years ago, Caltrans refused, despite arguments that coupler connections were stronger and more consistent than welded steel.

The issue was “nonnegotiable,” Caltrans told Fontana Steel Inc. in January 1995, two months before crews began assembling steel rebars for the seismic retrofit of the towering Mission Valley interchange in San Diego.

Within a year, Caltrans had determined that hundreds of the welds in those San Diego bridges were faulty and probably would fail in a moderate earthquake. They halted the project and demanded that contractors rip out thousands of welds, replacing them with the mechanical couplers the contractors wanted in the first place.

The agency then launched a three-year statewide review that uncovered faulty welds in several other bridges, including the busy Orange Crush interchange, where the Santa Ana, Orange and Garden Grove freeways meet.

Caltrans now plans to spend at least $4 million to pull out welded hoops from at least 18 Orange Crush bridge columns. Beginning in December, welds in critical support zones will be replaced with mechanical couplers. State legislators ordered an investigation into Caltrans’ handling of the weld issue. Assembly transportation committee members plan to begin their probe with public hearings in Orange County within two weeks.

Contractors say considerable time and angst--and millions of dollars--could have been spared if Caltrans had given them permission to use couplers when these structures were built. Caltrans disputes the contractors’ claims, saying earlier versions of the couplers didn’t work on some steel, and Caltrans approved couplers for use as soon as reliable ones were available.

“We moved ahead expeditiously,” said Jim Drago, a Caltrans spokesman. “All of that was launched after the problems surfaced in San Diego.”

But internal Caltrans memos show that even the agency’s top bridge engineer was frustrated by all of the foot-dragging on the use of couplers.

“I am very disturbed by the attitude of some designers and consultants who have decided on their own that welded splices are superior to mechanical couplers,” Jim Roberts, chief bridge engineer, wrote in an e-mail addressed to other engineers in July 1996 and obtained by The Times. “There is no factual evidence to support this view.”

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Couplers have been in existence for more than 25 years but have become more popular in the last five to eight years as designs improved, providing a more secure fit, industry experts say.

Couplers are used in place of welds to fasten two pieces of steel rebar together.

“They can be a very effective connection,” said Jack Moehle, director of the Pacific Earthquake Engineering Research Center at UC Berkeley.

“Welds are also a perfectly fine connection, but many of the mechanical couplers are more reliable.”

Caltrans acknowledges that its inspections of welds were lacking before the problems were discovered in San Diego four years ago.

Contractors blame Caltrans for the mess, saying better state oversight would have uncovered faulty welds sooner--before welds were encased in concrete.

Instead, Caltrans often approved the welds, and contractors then poured the concrete--only to be told months later that Caltrans was rejecting the work.

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At least a dozen contractors have filed claims against Caltrans, seeking reimbursement for correcting weld problems. Claims from the San Diego job alone top $20 million.

“If we had been allowed to use couplers, we wouldn’t have had these problems,” said Phil Fowler, vice president of Fontana Steel Inc., which hired the welding firm and installed the steel rebars on the San Diego project.

“We had almost 30,000 welds in those bridge columns. But they made us tear them all down and start all over again,” Fowler said. “We basically had to destroy a year and a half of work.”

His company also wanted to use couplers on a high-profile Los Angeles County project.

In 1994, Fontana Steel workers began using mechanical couplers to rebuild the tall Golden State/Antelope Valley interchange, which collapsed in the Northridge earthquake.

Midway through the project, Caltrans ordered the couplers removed from bridge columns.

“We had to cut them out and replace them with welds,” Fowler said.

Although Caltrans had approved couplers for use in bridge columns earlier that year, lab tests in 1994 showed the couplers weren’t compatible with a newer form of steel that Caltrans began using after the Northridge quake.

Couplers were left in the bridge footings of the $36.1-million Antelope Valley project but were removed from the vertical structural rebars.

Now Caltrans is worried about the welds installed there five years ago. An earlier bridge toppled in that same spot during the 1971 Sylmar quake.

Caltrans has spent nearly a year testing the welds. Fifteen welds have been removed for testing, and all were replaced with couplers. None of the welds being tested are in the critical support zone of the Antelope Valley bridge columns, said Drago, the Caltrans spokesman.

So far, the Antelope Valley welds have passed stress tests, Drago said. But Caltrans has ordered another round of tests. Caltrans hasn’t decided whether the welds in the Antelope Valley should be replaced.

“We want to assure ourselves that there isn’t anything out there that would compromise the integrity of the bridge,” Drago said. “It’s the prudent thing to do.”

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The Antelope Valley and Orange Crush are the only interchanges lingering on the state’s list of bridges with suspect welds.

The same welding company--Mejia Steel Welding of Riverside County--worked on the Antelope Valley, San Diego and Orange Crush, as well as 13 other bridge projects in Orange County, Drago said.

Seven of 56 welds in Orange Crush bridges failed during tests this spring. The welds were taken from two columns.

Repairs to the structure probably will last about a year, inconveniencing the more than 189,000 drivers who navigate the interchange each day.

(BEGIN TEXT OF INFOBOX / INFOGRAPHIC)

Keeping It Together

Caltrans plans to use mechanical couplers to replace welds in the Orange Crush interchange. A Fountain Valley company designed a coupler specifically for the project.

HOW IT WORKS

1. Place threaded sleeves over opposite ends of rebar hoop.

2. Screw curved steel threaded connector into sleeves completing hoop.

3. Tighten sleeves until hoop is snug against vertical bars.

A CLOSER LOOK AT ORIGINAL HOOP WELDS

Rebar was cut at 45-degree angle.

Weld was laid down in layers. A byproduct of welding, slag, must be cleaned off before next layer is added.

PROBLEMS THAT CREATE WEAK WELDS

Leftover slag weakens weld.

Air bubbles can form inside if proper temperature was not maintained during welding, weakening bond.

If the meltable material that forms the bond in welding is exposed to air for too long it attracts moisture, which weakens the weld.

Graphics reporting by RAOUL RANOA, MEG JAMES / Los Angeles Times

Sources: Haded Reinforcement Corp; William Castner, San Bernardino Valley College Welding Department; Caltrans