The Transbay Joint Powers Authority expects the repair of the two cracked girders in San Francisco's Salesforce Transit Center to begin next month and spill over into next year.
The cracked areas of the girders, which span 80 ft across Fremont Street, have been cut out and shipped to a testing laboratory in New York City, reported Dennis Turchon, TJPA's senior construction manager, to the TJPA board of directors, Nov. 8.
Testing is currently under way at the lab, LPI Inc., formerly known as Lucius Pitkin. Results are expected later this month, said Mark Zabaneh, TJPA's executive director.
The 1.2-million-sq-ft transit hub spans two city streets. TJPA opened the hub in early August and closed it on Sept. 25 after a ceiling installer noticed a crack in the bottom flange of one of the level-three girders, which supports a 5.4-acre public park above and a second-level bus deck below, via a hanger. The park also is closed.
Bottom-flange cracks are near the 8-ft-deep midspan of each shop-welded girder. No cracks were found in a similar system of twin girders that span First Street.
The TJPA board is calling for a complete structural evaluation of the 4.5-block-long transit center, to assure bus drivers and the 14,000 daily riders that the entire building is sound. "Was the engineering done right?" asked one director at the Nov. 8 meeting. "We need assurance."
On Wed., Nov. 14, representatives of all the parties involved with the structure will visit the lab and review the test results. This includes TJPA, structural engineer Thornton Tomasetti, contractor Webcor/Obayashi Joint Venture, steel fabricator Herrick Corp., material supplier ArcelorMittal and members of the original peer review panel and a second review panel assembled since the problems surfaced.
The group will review the steel sample testing procedures and the test results to determine a cause of the cracks. No repair design will begin until a consensus is reached on the cause, said Turchon.
"We are not going into a findings phase until everyone agrees on the testing," he added. The group even may order more tests, Turchon said.
TJPA also is trying to establish a prioritized timetable for the more sweeping review of the structure. "We will not reopen the facility unless we are 100% sure it is sound," said Zabaneh.
All related costs of the girder problems, including shoring, testing, repair design and remedial plan review and rework, are expected to be covered by the building's warranty, said TJPA.