FEMA P55 Coastal Construction Manual, Fourth Edition - Mad Cad

Volume II DETERMINING SITE-SPECIFIC LOADS 8
Worksheet 2. Flood Load Computation Non-Tsunamic Zone V and Coastal A Zone (Open Foundation) (concluded)
Equation 8.7 Wave Slam
Equation 8.8 Hydrodynamic Load
Equation 8.9 Debris Load
Equation 8.10 Localized Scour around Single Vertical Pile
S max = 2a=
Equation 8.11 Total Localized Scour Around Vertical Piles
S TOT = 6a + 2 ft (if grade beam and/or slab-on-grade present) =
S TOT = 6a (if no grade beam or slab-on-grade present) =
8.6 Tsunami Loads
In general, tsunami loads on residential buildings may be calculated in the same fashion as other flood
loads; the physical processes are the same, but the scale of the flood loads is substantially different in that the
wavelengths and runup elevations of tsunamis are much greater than those of waves caused by tropical and
extratropical cyclones (see Section 3.2). If the tsunami acts as a rapidly rising tide, most of the damage is
the result of buoyant and hydrostatic forces (see Tsunami Engineering [Camfield 1980]). When the tsunami
forms a bore-like wave, the effect is a surge of water to the shore and the expected flood velocities are
substantially higher than in non-tsunami conditions.
The tsunami velocities are very high and if realized at the greater water depths, would cause substantial
damage to buildings in the path of the tsunami. Additional guidance on designing for tsunami forces
including flow velocity, buoyant forces, hydrostatic forces, debris impact, and impulsive forces is provided
in FEMA P646, Guidelines for Design of Structures for Vertical Evacuation from Tsunami (FEMA 2008b).
For debris impact loads under tsunami conditions, see Section 6.5.6 of FEMA P646, which recommends an
alternative to Equation 8.6 in this Manual for calculating tsunami debris impact loads.
8.7 Wind Loads
ASCE 7-10 is the state-of-the-art wind load design standard. It contains a discussion of the effects of wind
pressure on a variety of building types and building elements. Design for wind loads is essentially the same
whether the winds are due to hurricanes, thunderstorms, or tornadoes.
Important factors that affect wind load design pressures include:
Location of the building site on wind speed maps
COASTAL CONSTRUCTION MANUAL
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