47.5 MB - The Whole Building Design Guide

4.4.3 Effects of High WindsThe highest gust wind speeds during Hurricane Katrina were typicallybelow the design wind speeds for this area, which rangefrom 120 to 150 mph. Despite this, many emergency response facilitiessustained damage that disrupted their operations, and in afew cases shut down the facility. Most of the damage was confinedto the building envelope. Portions of metal roofing were liftedand peeled off; aggregate roof surfacing was blown off, becomingwind-borne debris; and roof-mounted equipment, including communicationtowers and antennae, were toppled or broken. Metalwall-cladding panels detached or peeled off on a number of facilities,exposing the interior to pressurization and rainwaterpenetration. Doors and windows were damaged by wind-borne debris,allowing the penetration of wind-driven rain.4.4.4 Site SelectionIdeally, the emergency response facilities should not be located ina floodplain or a site exposed to other types of hazards. However,emergency response facilities, especially fire rescue and police stations,must contend with geographic limitations pertaining to sizeand adequate coverage of their service areas that frequently placethem in hazardous locations. Many of the facilities flooded duringKatrina were located in designated floodplains. However, thisfact alone does not explain the catastrophic damage sustained byfacilities such as the police and fire stations in Pass Christian, Mississippi(see Figure 4-32), because most of the facilities damagedby flooding were built above the minimum required elevations.The primary reason for the widespread damage is the catastrophicnature of the flooding, caused by extremely high storm surge andthe failure of levees in New Orleans.In locations where the emergency response facilities were built toa higher standard than required by local regulations, the adverseeffects of Katrina were substantially reduced. The Jackson CountyEOC occupies the second floor of a municipal building locatedin Pascagoula, Mississippi. An examination of the storm surgeflooding associated with different hurricane scenarios indicatedthat the site would be inundated during a Category 3 hurricane.Consequently, the county decided to design the building to be4-48 OBSERVATIONS ON THE PERFORMANCE OF CRITICAL FACILITIES