Fort Jefferson, FL, USA
ODB was asked to do the structural assessment of a typical bay of brick vaulting in the casemate of Fort Jefferson, built in the mid-19th century off the coast of Florida and the largest brick construction in the Americas.
Based on a site visit, a qualitative assessment of the brick vault was made, and the significance of interior cracking discussed. A three-dimensional structural analysis was then used to calculate the minimum horizontal thrust acting on the scarp wall from the upper and lower casemate vaults. These thrust values were then used to quantify the stability of the outer wall. In particular, spalling of the exterior brick has led to concerns about the structural capacity of the exterior wall in supporting the thrust of the vaults.
The goal of ODB's work was to assess the importance of the exterior spalling, and quantify the stability of the exterior wall in resisting the thrust of the brick vaults. Our analysis showed that the casemate vaults and walls did not need the suggested steel bracing.
- United States National Park Service