A field-based monitoring technique that utilizes measurements of fire induced vibration was developed and first demonstrated under a previously funded research effort. This report details the findings of the ensuing 3-year endeavor in which significant improvements were made to both field-test and analysis procedures. A real-time monitoring tool has been developed and numerous full-scale burn tests on a variety of structures have been completed. A significant contribution of the research stems from the use of system stability theory to aid in the interpretation of the field measurements. The techniques described in this report can be used to monitor burning structures and to provide visual indicators that track changes in structural stability.

Structural health monitoring has been largely promoted as a means for assessing the condition of buildings and other critical structures in the aftermath of significant events. Support for installation of real-time monitoring devices and systems, however, continues to lag due in part to the absence of clear and convincing benefits to owners and to the
structures themselves. A case can be made that a fresh approach, or application, may be needed to bolster the case for real-time structural health monitoring. Firefighting operations and the accompanying risks are typically scrutinized and reviewed anytime loss of life results. In recent history, no single event has drawn more attention to the technology and methodology of modern firefighting technique than has the collapse of
the World Trade Center Towers.

The collapse of those structures and the corresponding loss of life reveled a vulnerability in the absence of real-time health monitoring that may have informed firefighters of the weakening structural conditions around them. Under a previous research effort funded by the Building and Fire Research Laboratory and the National Institute of Standards of
Technology (BFRL/NIST), a new methodology and application for health monitoring was introduced.

Fire-induced vibration based health monitoring was first demonstrated in tests conducted on a single-family wood frame structure in Kinston, North Carolina (August 2001). In those tests, a heating oil tank was mounted on the roof of the structure in an effort to induce roof collapse during burn. The objective of that test was to evaluate the possibility of measuring fire-induced vibrations in a burning structure that correlated with weakening conditions leading to a significant
collapse event. Those tests demonstrated for the first time, that fire was capable of exciting dynamic structural vibration responses that provided real-time indication of impending collapse.