Volume 9, Issue 4 (April 2012)
Evaluation of the Structural Sealant for Use in a Four-Sided Structural Sealant Glazing Curtain-Wall System for a Hospital Building
Cathedral Hill Hospital (the California Pacific Medical Center) is a 15-story building designed to be constructed in downtown San Francisco. The curtain-wall system for this building is primarily of unitized design employing a four-sided structural sealant glazing (SSG) system. This paper initially introduces the building and its curtain-wall design. Next, the summary of the results of full-scale racking tests on stick-built mockups of the curtain-wall system developed to evaluate the structural sealant performance are presented. Stick-built mockup, instead of unitized system, was chosen to initially evaluate the behavior of sealants under racking conditions. The mockups were designed to determine the behavior of the glass, framing, connections, and more importantly, the structural silicone under racking displacements following the AAMA 501.6 protocol. The test results (stress–strain relationships) on the structural sealant to determine tensile adhesion properties at selected temperatures and UV exposures are discussed and comparisons to the finite-element analysis results are presented. The wind load and seismic design of the sealants, including the finite-element modeling and analysis of a typical panel to evaluate the stresses in the structural sealants, are presented as well. The allowable stress issue in structural sealants for seismic design of four-sided SSG systems is discussed in light of the new information generated for this project.