AIC's 44th Annual Meeting

The Department of Buildings of the City of New York mandates that Construction Protection Plans be prepared and filed to protect historic buildings from damage caused by construction on nearby buildings. The directive sets a threshold for vibrations, but, in buildings subject to the requirement, fragile objects and assemblies such as stained glass windows require special attention. At Congregation Shearith Israel on Central Park West in New York City, a separate construction protection plan was prepared for the original Tiffany windows. BCA documented the windows’ conditions and called for minor repair and precautionary work. Three heavily damaged windows were removed from the site for restoration during construction operations. In lieu of physical interventions to the remaining windows, BCA devised a separate vibration monitoring system mounted directly on the windows to monitor the effects of construction.   The monitoring program developed for the project by ANA incorporates a series of triaxial geophones mounted on the vertical stabilization bars at mid height or on saddle bars where no vertical bars exist. The geophones were configured to trigger if the measured peak particle velocity exceeded a preset threshold (well below the levels set for typical building assemblies), and send a series of alarm emails if the displacement recorded during a trigger event exceeded the displacement thresholds. The monitoring program has thus far been highly successful, acting as a reasonable alternative to the standard approach of invasive bracing, or even removal, while leaving the windows fully functional. Periodic checking of the window conditions against preconstruction documentation determined that no damage had occurred.   The paper will describe the considerations resulting in the accepted approach. The designer of the monitoring equipment will discuss the design and installation and the specific challenges of working with the historic windows in an active house of worship.