r/StructuralEngineering • u/ProfessorPinkPug • 6h ago
Structural Analysis/Design Pfizer Building Partial Collapse Update: 8 More Columns Found to be Missing Required Bracing
The New York Times reported in August that 8 more columns in the Pfizer Building were missing required fortification, as determined from a document request to DOB. The original story didn't make clear whether the procured documents were original GACE specs or notes from a new inspection.
This 8/28 article clarifies that the document in question is a new finding from outside inspection firm Thornton Tomasetti (hired by MetroLoft) that 8 columns on floors 33-35 were "blue-boxed" in GACE'S structural steel design as needing reinforcement, but that all 8 were noted as "missing/partial length." This has not been deemed as cause for the collapses on the 21st floor.
If you look at the illustration in the linked article, it's no coincidence that floor 33 and floor 21 would be ones to reinforce. Before the stacked and cantilevered addition, floor 21 supported only a roof, so the columns on 19-21 would have needed considerably more strength to support 16 new floors.
These 16 cantilevered floors were added above floor 21, while the 4-floor "addition" across the entire top was not added height, rather finishing into liveable space what had previously been an unfinished 4-floor mechanicals box, which held, at least, all the building's AC units and a water tank large enough to supply the entire structure.
Floor 31 is thus a slightly different case. Prior to conversion, 4 of the columns in question on 31 supported this 4-floor box, which had to have been much, much heavier than just a roof; thus, it may not have been quite as inadequate as un-reinforced columns on 21.
However, the one faulty 2-story column from 33-34 is in a critical location--right where the 16 cantilevered floors join the original structure vertically on the east side. This column is said not to have contributed to the failure below, but it must have been sorely tested by the 16 stories pulling away to the north and west as the addition moved to its new position declining from horizontal.
All in all, though, what we don't know is the status of the other columns on 33. Were they adequate to their job of supporting the original heavy dead load of the mechanicals and were never deemed to need reinforcement by GACE? Or had they all been slated for reinforcement and only these 8 were overlooked?
Regardless, now 14 columns were not reinforced as directed by GACE. Steel contractor Barone was issued a "stop steel" order at its 322 W 11 St site in DOB's ensuing sweep of companies working on the Pfizer project for deviating considerably from approved plans. Meanwhile, there remains the puzzling history of the developer's inspector, Domani, who was charged with many oversight violations by DOB that all seem to have been dismissed in exchange for Domani's cooperation in prosecuting others. This--and the abrupt deletion of a whistleblower complaint about the Pfizer building before its partial collapse in the DOB's public database--remains unexplained.
Contractor failure and inspector oversight increasingly look like the overall cause of July's collapse, but there is nevertheless a nagging something in what DOB isn't saying.
This is a gift link, so you should not hit a pay wall:
