February 24, 2011
Innovation in Motion: Cable Catchment Systems
by Hinman Team
Preservation of exterior window systems is an important aesthetic consideration when renovating historic buildings. The need to improve the protective quality of this component of the building envelope while maintaining the existing façade expression presents both challenges and opportunities to apply innovative threat mitigation technologies. In exploring various window retrofit options, blast engineers must balance the demands of likely threat scenarios against a variety of other design objectives pertaining to cost, energy performance, window operability and constructability. The final result is, ultimately, a system that is a threat mitigation solution uniquely tuned to meet project specific goals and preserve the identity of the historic structure.
In a recent project, Hinman has explored the use of cable catchment systems as a cost-effective means of providing blast protection for historic buildings. This system consists of steel cables installed behind glass panes and anchored into the structural system above and below each window. In pursuit of this effort, a three-dimensional Finite Element (FE) model of the proposed system was first developed to simulate the cable catchment behavior. This was followed by a series of shock-tube explosive tests sponsored by the General Services Administration (GSA) to validate the behavior predicted by the analytical model and to confirm the capacity of the system. Following the tests, the FE model was refined to incorporate the findings of the physical explosive test data.
Both the in-field test results and final FE model showed that the cable catchment system demonstrated considerable potential as an air-blast mitigation solution while preserving the historic nature of the building and meeting window operability and maintenance needs. Additionally, considering the budget and time constraints of renovation projects, development of this broad application engineered solution validated by analytical and empirical data has minimized the need for extensive configuration-specific physical tests of future window retrofit options. Ultimately, Hinman expects that the validated FE analysis will serve as a foundation for future studies and provide a computational platform for the optimization of catchment system configurations to be used as a pre-engineered retrofit solution.
The analysis and testing will be presented at the ASCE Structures Congress in Las Vegas on April 14, 2011.