Impact of Falling Debris in Structural Collapse Progression

This award will lead to improved safety and resiliency of buildings by enabling the engineering community to better understand the collapse process of buildings due to various causes, such as earthquakes, wind, collision, deterioration, poor design, and construction errors. Structural collapse can occur due to local failures that progress throughout the building’s members. While the potential local failure is nearly impossible to eliminate, the progression of collapse by the impact of falling structural members can be limited. However, current engineering analysis methods are lacking in the ability to predict the velocity and shape of the falling debris, the loss of energy on impact, and the response of the structural elements to the debris impact. Therefore, there is no suitable way to predict if the falling debris will cause a progression of collapse. Understanding how falling debris can lead to further collapse can lead to techniques to halt collapse in buildings and prevent fatalities. The improved analysis tools developed in this award will serve to advance national prosperity and welfare through future improved code provisions and detailing standards that will provide additional resistance to structural collapse. In addition, this project will provide outreach to diverse high school students and educate college undergraduate and graduate students. This award contributes to the National Science Foundation (NSF) role in the National Earthquake Hazards Reduction Program (NEHRP) and the National Windstorm Impact Reduction Program (NWIRP). The goal of this project is to achieve a fundamental understanding, through experimental and analytical studies, of falling structural debris loading. Improved analysis tools (modeling methods and simplified analysis) will be developed to improve collapse prediction and lead to future designs that can efficiently limit collapse progression. The research will generate critical experimental data and analytical models to provide answers to three fundamental impact questions: (1) velocity, shape, and condition of the falling debris, (2) amount of energy lost and how to analyze the impact, and (3) dynamic response (strength and ductility) of the impacted beam. The project will achieve its goal through (1) analysis of previous collapse tests to determine the velocity, shape, and condition of falling debris, (2) experimental drop beam impact tests to evaluate energy transfer on impact and strength, and (3) detailed finite element method numerical analysis of substructure and prototype buildings to analyze the effects of falling debris and provide validated modeling approaches. The results will be used to develop detailed and simplified analytical tools that can analyze falling debris for prediction of collapse progression. Data from this project will be archived in the NSF-supported Natural Hazards Engineering Research Infrastructure (NHERI) Data Depot (https://www.DesignSafe-ci.org). This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.