The September 11, 2001 terrorist attack on the WTC and Pentagon has created an infrastructual catastrophe. While the recovery effort is underway, engineers from FEMA and ASCE's disaster response teams are concurrently inspecting adjacent buildings for damage. The objective of this research is to conduct post-disaster reconnaissance at the affected sites in order to recover ephemeral data for detailed damage assessment.
This SGER award is to support a team from the University of Florida in using a new land-based laser system to produce very high-resolution 3-D "maps" of both interior and exterior areas of damaged buildings. This system, based on airborne laser swath mapping technology, can quickly generate very valuable data, especially on damage related to deformations and cracking. The reflection of laser pulses (at 2 kHz) is used to obtain X, Y, Z coordinates and ultimately a digital elevation model. This results in photographic-like images and spatial coordinates with an absolute accuracy of 4-5 mm and a relative accuracy of 1-2 mm. The spacing of data points is user selectable and can be extremely small, but for this research, it is anticipated that spacing of several cm for large areas and several mm for smaller areas such as rooms would be used. The laser system is integrated with digital photography to compliment building damage analysis. For example, exposed beams and columns can be checked for plumbness and deformations; exterior walls for lateral deformations, architectural damage and cracking. Other methods of obtaining these data are very time consuming and less accurate.
The purpose of the data collection is threefold. First, systematic collection of damage data from structures damaged, but not destroyed, will aid in the assessment of the structural integrity of these buildings. These data should expedite damage appraisal and if warranted, their eventual repair. Second, the data will serve as a valuable resource for future research related to performance of structures subjected to terrorist attack, explosions, fires, etc. It should help in the development of methods to minimize damage from such occurrences; and may result in better designs of urban structures. Third, this work will support the development of land based laser swath methods that have tremendous applications in civil engineering and construction. The PIs are leaders in the application of this technology to civil engineering related issues.
