47.5 MB - The Whole Building Design Guide

Figure 2-7 shows the general relationship between velocity andstillwater depth. For design purposes, actual flood velocities are assumedto lie between the upper and lower bounds. Conservativedesigns will take into account the upper bound velocities.Figure 2-7:Velocity as a function ofstillwater flood depth2.1.2.4 Hydrostatic LoadsHydrostatic loads occur when water comes into contact witha building or building component, both above and below theground level. They act as lateral pressure or vertical pressure(buoyancy). Hydrostatic loads on inclined or irregular surfacesmay be resolved into lateral and vertical loads based on the surfacegeometry and the distribution of hydrostatic pressure.Lateral hydrostatic loads are a direct function of water depth (seeFigure 2-8). These loads can cause serious deflection or displacementof buildings or building components if there is a substantialdifference in water levels on opposite sides of the component(or inside and outside of the building). Hydrostatic loads are balancedon foundation elements of elevated buildings, such as piersMAKING CRITICAL FACILITIES SAFE FROM Flooding2-21