BACKGROUND

Tornadoes are known to produce some of the strongest winds on earth; however, a sufficient understanding of the magnitude, frequency, and structure of these winds has not yet been obtained. Gaining this knowledge is critical for emergency planning and engineering designs that enhance life safety and minimize damage.  Direct measurements of tornado winds are rare and difficult to obtain, and it is thus necessary to use proxy methods (most notably wind damage to structures) to estimate tornado wind speeds. These tornado wind speed estimates are necessary for the production of safe designs that protect lives and property.

On November 16-17, 2015, an intense tornado outbreak severely damaged a group of engineered structures at the Halliburton Oilfield Services facility east of Pampa, TX.  The Halliburton facility contained multiple types of engineered structures for which structural resistances could be estimated, thereby enabling the estimation of tornado wind speeds required to cause the observed damage. Due to safety and security concerns, the facility owners prohibited access to the facility, so that it was not possible for investigators to make contact measurements or conduct close-range forensic investigations of the damaged structures. The facility owners were agreeable to the research team acquiring photographs and lidar scans from the fence line and to the use of unmanned aerial systems above the property. To collect this critical damage data, it was therefore necessary to utilize remote-sensing platforms.

The major goals of this project are:

• to rapidly preserve perishable evidence of damage to engineered structures caused by a severe tornado, using multiple remote-sensing (i.e. non-contact) measurement and recording platforms, to facilitate future investigations of tornado-structure interactions as well as estimations of wind speeds causing these damages for use in validating or revising wind speed estimates in the Enhanced Fujita (EF) Scale of tornado intensity;
• to rapidly preserve a visual record of contents and locations in the debris field extending approximately 1 mile downwind of the Halliburton facility to facilitate future investigations of debris flight and tornado actions; and
• to archive the evidence and make it available to other researchers through the NHERI DesignSafe, to facilitate the validation of tornado loss models, debris-flight models, and further studies of tornado-structure interaction.

INTELLECTUAL MERIT

The resulting data have served as the basis for collaborative, multi-disciplinary studies emphasizing the accurate and highly detailed preservation of damage scenes; heightened understanding of the complex wind structure of tornadoes; validation or refinement of tornado wind speed estimates employed in the EF Scale; inclusion of new damage indicators in the EF; and development of more resilient infrastructure. 

Preservation of 3-D damage scenes enables researchers to validate wind-damage prediction models, via physical modeling, computer modeling and other predictive damage modeling (e.g., loss estimation and risk assessment models). Preservations using remote-sensing platforms minimize collection times, costs, and efforts and also facilitate forensic structural engineering investigations whenever access is limited due to safety and security concerns.

These data also promote the investigation of rapid remote-sensing-based damage assessments using a variety systems and platforms and can serve as a basis for future comparative research examining the utility of various view angles, platforms, and image resolutions which will facilitate progress toward automated damage assessments. Each platform has potential use in preservation of damage conditions for all types of wind storms and in the rapid, automated detection of wind damage.

BROADER IMPACTS

This endeavor has advanced the natural hazards research emphases in three university programs: the WTAMU School of Engineering, the University of Nebraska-Lincoln, and the Texas Tech University National Wind Institute. This endeavor has supported the student training  and professional skill development of one graduate student at UNL and collaboratively four undergraduate students at WTAMU. Futhermore, the project has helped to elevate the education of students by exposing them to real-world  structural response and load-distribution under extreme loads in the classroom.  This includes one undergraduate and graduate course at UNL.

Last Modified: 06/29/2018
Modified by: Richard L Wood