Assessing Wind Versus Surge Damage

Assessing Wind Versus Surge Damage, Reflecting On What Was Learned From Hurricane Katrina

Featured Article from:  The Forensic Engineering Report, Volume 18, Issue 4

 

A tremendous amount of information about the assessment of damage to structures in the determination of wind versus surge became available following Hurricane Katrina and the damages experienced there. Aerial photographs published by NOAA became of particular value as did topographical maps and aerial photographs taken prior to the hurricane. Utilizing these resources provided a means for engineers to supplement on-site observations.

Forensic meteorologists were also of particular value in providing opinions of the timing of events with regards to the wind versus surge components of hurricane damages. In many instances without this data, it would be impossible to determine the cause of damages. Professional engineers had a very daunting task to determine the forces that caused the destruction.

Structural engineers must understand the forces from surge water versus those of wind, including dynamic and hydrostatic conditions. The velocity of wind gusts and surge forces are taken into consideration.

Complete demolition of superstructures was consistent with powerful forces of storm surge, while structures located at higher elevations may be more prone to damage from greater wind forces.

The ethical pressures being faced by engineers in the determination of flood versus storm serge were also daunting insomuch that many property owners had no flood insurance. The determination of wind versus flood damages could bring financial ruin to individuals or families. Following the ASCE Code of Ethics provides some key factors to deal with these pressures such as honesty, integrity and objectivity.

The tremendous volume of buildings that needed to be inspected was also a problem. The Investigative Engineers Association put together guidelines for member professional engineering firms to provide catastrophe response in a organized fashion that would allow for a greater volume of investigations to happen in a more timely fashion. Time was an important factor to consider as there were over 250,000 people displaced by Hurricane Katrina and rebuilding efforts were not likely to start until insurance issues were resolved.

The Investigative Engineers Association organized a Catastrophe Response Committee consisting of professional engineers who were dealing with the situation in Louisiana and the gulf coast following the storm, to ascertain issues experienced and a way to deal with major catastrophic events such as this that may cause widespread damage in the future. The project included dealing with ways to organize a team of professional engineers and the distribution of assignments by area coordinates to eliminate as much windshield time as possible. Additionally the association put together the www.ienga.com website which enables its users, whom are all members of the I-ENG-A organization, to search for engineers by discipline, by state licensure and by availability. Technical training for CAT response including report formats, report timelines, safety, briefing, debriefing, structure of the CAT response team, the roles of Team Leaders, Investigative Engineers and Registered Professional Engineers, etc., were discussed as well as insurance requirements.

While the role of the I-ENG-A headquarters includes CAT response training and assistance with job processing, tracking, and data collection, the local member firm is to serve as the host or as the event management office. The models discussed teams of 3-4 engineers who would complete 6-8 assignments /day depending upon the complexity and travel time involved.

In conclusion, having engineers who are trained in these efforts with a plan in place before a catastrophe occurs can save a lot of time and money for all parties involved when a catastrophe does strike. If you would like to discuss catastrophe response with firms who may serve as your host, please feel free to contact association headquarters or visit www.ienga.net or www.ienga.com to locate the firm or firms near your areas of concern.

Sources: Forensic Engineering: Proceedings of the 4th Congress, October 6-9, 2006, Paul A. Bosela, Norbert J. Delatte, I-ENG-A CAT Committee