47.5 MB - The Whole Building Design Guide

Figure 3-3: Design wind speeds for community sheltersfrequently. Damage incurred in design level events is typically associatedwith inadequate design, poor installation, or materialdeterioration. The exceptions are wind-driven water infiltrationand wind-borne debris (missiles) damage. Water infiltration is discussedin Sections 3.3.3.1, 3.3.3.2, and 3.3.3.3.Tornadoes: Although more than 1,200 tornadoes typically occureach year in the United States, the probability of a tornado occurringat any given location is quite small. The probability ofoccurrence is a function of location. As shown in Figure 3-2, onlya few areas of the country frequently experience tornadoes, andtornadoes are very rare in the west. The Oklahoma City area is themost active location, with 112 recorded tornadoes between 1890and 2003 (www.spc.noaa.gov/faq/tornado/#History).MAKING CRITICAL FACILITIES SAFE FROM High Wind3-7