47.5 MB - The Whole Building Design Guide

Determining potential scour is critical in the design of foundationsto ensure that failure during and after flooding does not occur asa result of the loss in either bearing capacity or anchoring resistancearound the posts, piles, piers, columns, footings, or walls (seeFigure 2-11). Scour determinations require knowledge of the flooddepth, flow conditions, soil characteristics, and foundation type.At some locations, soil at or below the ground surface can be resistantto localized scour, and calculated scour depths based onunconsolidated surface soils below will be excessive. In instanceswhere the designer believes the underlying soil at a site will bescour-resistant, the assistance of a geotechnical engineer or geologistshould be sought.Figure 2-11:Local scour underminedthis shallow foundation(also note that the buildingwas not anchored to thefoundation).2.1.3 FLOODPLAIN MANAGEMENTREQUIREMENTS AND BUILDING CODESThe NFIP is the basis for the minimum requirements included inmodel building codes and standards for design and constructionmethods to resist flood damage. The original authorizing legislationfor the NFIP is the National Flood Insurance Act of 1968 (42U.S.C. 4001 et seq.). In that act, Congress expressly found that “aprogram of flood insurance can promote the public interest byencouraging sound land use by minimizing exposure of propertyto flood losses…”2-28 MAKING CRITICAL FACILITIES SAFE FROM Flooding