47.5 MB - The Whole Building Design Guide

The experience of Hurricane Katrina shows that the damagecaused by rising water generally renders shelters uninhabitableand useless, further aggravating the recovery process. In most casesthe mechanical and electrical systems were disabled as a result offlooding, which allowed the internal temperatures to reach intolerablelevels. Additionally, the flood-induced back-flow of plumbingsystems created unsafe sanitary conditions in most of the facilities.4.3.3 Effects of High WindsHurricane Katrina reached maximum gust wind speeds of 130mph at landfall, with hurricane force winds extending outward105 miles from the center of the storm (FEMA, 2006). Numeroustornadoes were also spawned by the hurricane, contributing tofurther damage as the storm moved northward. There were 11 tornadoesrecorded in Mississippi, with 17 more in Georgia, and 4in Alabama. Current model building codes in the areas affectedby Hurricane Katrina generally require buildings to be designedto meet 120 to 150 mph design wind speeds. Some buildings,however, were constructed prior to the implementation and enforcementof the current model codes.Wind damage was most evident on the building envelope, especiallyroofs, walls, doors, and windows, as well as other exteriorelements, such as walkway canopies and exposed mechanical andelectrical equipment. The extent of the damage was dependenton the force of the wind, the type of construction, and the configurationof the buildings. Once a building envelope was breached,the interior of the building sustained additional damage, both asa result of pressurization and rainwater penetration. The most severedamage in the interior was observed on the least durablefinishes, such as acoustical ceilings, wood doors and trim, andbuilding contents such as office equipment, furniture, and books.Most of the educational facilities used as place of refuge shelterssuffered wind damage to the roofs and windows. When a portionof the roof was lost or a window was broken, rainwater was ableto enter the building, causing damage to the interior. In some instances,the occupants were forced to relocate to other buildingsduring the storm, because of the danger of progressive buildingfailure (see Figure 4-17).OBSERVATIONS ON THE PERFORMANCE OF CRITICAL FACILITIES4-29