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<br /> <br />CHAPTER II <br /> <br />FLOOD AND WIND HAZARDS <br /> <br />FLOOD AND WIND HAZARDS <br /> <br />Flooding and wind have various characteristics <br />and parameters that determine the magnitude of <br />forces produced by these natural hazards, <br />Because a manufactured home installation can be <br />affected by flood and wind induced forces acting <br />on the body of the unit, the supporting foundation <br />structure, and the anchoring system, these forces <br />and their application to manufactured homes <br />become critical and must be recognized, - - <br /> <br />lapse, and foundation/anchoring system failure, <br />Hydrodynamic forces, depicted in Figure 2,2, <br />are those caused by the flow of floodwater around <br />and against the manufactured home or founda- <br />tion, Hydrodynamic forces are lateral in nature and <br />apply directly against the structure, They include <br />drag forces as water flows around the structure <br />and negative pressure caused by eddies on the <br />downstream side, ' <br /> <br /> <br />-~ ----HA-Z-A-RE>S-FR0M-Fl00DS~ ---- -- --~ <br /> <br />Flood Forces-Floodwaters cause pressures or <br />forces on the surfaces of manufactured homes <br />and their supporting foundations, These forces are <br />of three basic types: hydrostatic, hydrodynamic, <br />and debris impact. <br />Hydrostatic forces are caused by water either <br />above or below the ground surface, free or con- <br />fined, that is essentially stagnant. These forces <br />result at any point of floodwater contact with a <br />structure, Hydrostatic pressures are equal in all <br />, directions and always act perpendicular to the sur- <br />face on which they are applied, As Figure 2.1 in, <br />dicates, the loads can act vertically on structural <br />members, such as floors and foundation slabs, <br />and can act laterally on upright structural <br />elements, such as walls, piers, piles, or posts, <br /> <br /> <br />Figure 2.1 Hydrostatic Forces <br /> <br />Hydrostatic forces have the ability to cause <br />manufactured home flotation, floor and wall col- <br /> <br />Figure 2.2 Hydrodynamic Forces <br /> <br />Hydrodynamic forces have the ability to cause <br />foundation system failure, increase erosion and <br />scour around foundation system components, and <br />cause damage to the manufactured home struc- <br />ture, as shown in Figure 2,3, <br /> <br /> <br />Figure 2.3 Damage From Hydrodynamic Forces <br /> <br />15 <br />