Investigators for San Francisco's Trans- bay Joint Powers Authority are search- ing for the cause of brittle fractures in the tapered bottom flanges of twin 80-ft-long built-up plate girders in San Francisco's Salesforce Transit Center. With shoring in place to relieve the loads on the problem girders, which span Fremont Street, shoring contractors are turning their attention to similar parallel girders that span nearby First Street, though no cracks have surfaced there. "Because Fremont and First streets are similarly designed, to be prudent, we have decided to [shore and] reinforce First Street as a proactive measure," said Mark Zabaneh, executive director of the TJPA, in a statement released Oct. 5.
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