47.5 MB - The Whole Building Design Guide

Step 1: Determine the basic wind speed from ASCE 7. As thebasic wind speed increases beyond 90 mph, the risk of damage increases.Design, construction, and maintenance enhancementsare recommended to compensate for the increased risk of damage(see Section 3.3).Step 2: For critical facilities in hurricane-prone regions, refer tothe design, construction, and maintenance enhancements recommendedin Section 3.4.For particularly important critical facilities (such as hospitals)in remote areas outside of hurricane-prone regions, it is recommendedthat robust design measures be considered to minimizethe potential for disruption resulting from wind damage. Becauseof their remote location, disruption of such facilities couldseverely affect the occupants or community. Some of the recommendationsin Section 3.4 may therefore be prudent.3.2.2.2 Existing BuildingsThe resistance of existing buildings is a function of their originaldesign and construction, various additions or modifications, andthe condition of building components (which may have weakeneddue to deterioration or fatigue). For existing buildings, a two-stepprocedure is also recommended.Step 1: Calculate the wind loads on the building using the currentedition of ASCE 7, and compare these loads with theloads for which the building was originally designed. The originaldesign loads may be noted on the contract drawings. Ifnot, determine what building code or standard was used to developthe original design loads, and calculate the loads usingthat code or standard. If the original design loads are significantlylower than current loads, upgrading the load resistanceof the building envelope and/or structure should be considered.An alternative to comparing current loads with originaldesign loads is to evaluate the resistance of the existing facilityas a function of the current loads to determine what elementsare highly overstressed.3-30 MAKING CRITICAL FACILITIES SAFE FROM High Wind