In 2017, Old Structures began work on the engineering portion of the restoration of the Serbian Orthodox Cathedral of Saint Sava. The design team is headed by Don Zivkovic and Brian Connelly of Zivkovic Connelly Architects; Shaquana Lovell from OSE performed most of the structural design. The first step of any project is to figure out what our scope is, and here that was obvious: reconstruct the roof and floor as needed to make the ruins back into a useable church. (Obviously there is more detail than that, but that’s the core.) The second step is figuring out what constraints there are, as they may determine much of the design. In this case, we were part of the group that made the decision that the new structure would be fully compliant with the current New York City Building Code. Without going into the details, this was not an absolute necessity for us to move ahead, but it seemed to provide the best path.
Part of code compliance was structural analysis. It’s hard to overstate how primitive the state of structural engineering was in the US in the early 1850s when the cathedral was built. Not only was there no such thing as structural engineering dedicated to building design, structural engineering of any type was using very primitive analytic tools. In any case, there’s no evidence that any engineering at all went into the original design, just as there is pretty much none for any building this age in New York.
Our new design includes steel roof trusses in the same basic configuration as the original wood trusses, and steel girders supporting a concrete-slab floor in the sanctuary, in place of the wood joists, wood plank, and (a small area of) stone slab floor that were there. The old roof was a complete loss in the fire; the old floor was roughly 20 percent destroyed and the remainder was badly damaged. Our design of the new roof and new floor obviously followed modern standards, but we also performed the first-ever analysis on the masonry walls.
It came as no surprise that the masonry walls basically worked under current code. (Current code wasn’t written in the expectation that people would be building using unreinforced rubble schist several feet thick, which is why I need the “basically” in that sentence.) The best proof of structural adequacy is long-term performance, and the walls of the cathedral have held up through 150 years of use and weather, through neglect and restoration, and through the thermal and loading stress of the fire and roof collapse.
Monday: Old repairs.
Tuesday: Some history of the building.
Yesterday: Temporary conditions.
Tomorrow: New steel.