Investigators closer to determining cause of Salesforce Transit Center's cracks
- A clearer picture of what caused steel girders at the $2.2 billion Salesforce Transit Center in San Francisco to develop large cracks is starting to emerge, according to Engineering News-Record. The new building was shut down in August and an investigation is ongoing.
- Michael Engelhardt, a University of Texas at Austin engineering professor and chair of the Metropolitan Transportation Commission’s peer review panel overseeing the investigation, told ENR that three conditions contributed to the cracks: low-fracture toughness inside steel plates, the standard steel fabrication process and stress levels from live loads. Another area of the transit center has the same “bridge-like” girder system but did not develop cracks because of a fabrication variation, he said.
- Because the project had passed all inspections and technical design reviews during the construction process, the commission is expected to propose changes to building practices, policies and codes in an effort to prevent similar issues with future construction.
Last month, experts retained by the MTC peer review panel investigating the cracked beams proposed a repair that would restore the "original design capacity” and put the transit center one step closer to reopening. Engineering firm Thornton Tomasetti explained that the capacity could be restored through the targeted installation of bolted cover plates. However, the investigation so far has revealed that even with the cracks, the flawed steel beams could still support the weight of the building and its occupancy loads.
According to the authority, the panel should finish its review and approve the proposed fix this month, at which point a repair schedule can be finalized. The panel is also developing recommendations for additional inspections at the transit center prior to reopening. During a November meeting of the authority's board of directors, the members called for an inspection of the entire facility before opening it again to make sure there are no additional structural issues.
Testing, additional inspections and the cost of repairs are extra expenses that the authority said are the responsibility of contractor Webcor Obayashi under the same type of warranty that most contractors, subcontractors and material suppliers provide upon completion of construction projects. The majority of contractors never have to make good on these guarantees, but when they do, it can cost them big bucks.
In a similar situation, yet on a smaller scale, back in 2017, Parsons Brinckerhoff, The Robert B. Balter Co. and Facchina Construction Co. agreed to fork over $25 million to help cover the cost of concrete and steel beam remediation at the $140 million Silver Spring (Maryland) Transit Center, though that amount didn’t fully cover what the county had to pay for repairs.
Montgomery County alleged in a lawsuit that the contractors made misrepresentations in the transit center's design documents, which led to concrete cracking and safety issues. The contractors made repairs but maintained that the center was safe and that the county should have addressed any structural issues during construction.
- Engineering News-Record 'Perfect Storm' Caused Fractures at San Francisco Transit Hub
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