47.5 MB - The Whole Building Design Guide

Buoyancy and uplift: If below-grade areas are essentially watertight,buoyancy or uplift forces can float a building out of the ground orrupture concrete floors (see Figure 2-15). Buildings that are notadequately anchored can be floated or pushed off foundations. Althoughrare for large and heavy critical facility buildings, this is aconcern for outbuildings and portable (temporary) units.Figure 2-15:Concrete floor rupturedby hydrostatic pressure(buoyancy). HurricaneKatrina (2005)Duration: Long duration saturation can cause dimensional changesand contribute to deterioration of wood members. By itself, saturationis unlikely to result in significant structural damage to masonryconstruction. Saturation of soils, a consequence of long durationflooding, increases pressure on below-grade foundation walls.Velocity, wave action, and debris impacts: Each of these componentsof dynamic loads can result in structural damage if buildings arenot designed to resist overturning, repetitive pounding by waves,or short-duration impact loads generated by floating debris.Erosion and scour: Structural damage is associated with foundationfailure when erosion or scour results in partial or completeremoval of supporting soil (see Figure 2-16). Erosion of slopes, especiallyunprotected slopes, can lead to slope failures and loss offoundation supporting soil.MAKING CRITICAL FACILITIES SAFE FROM Flooding2-45