FEMA P55 Coastal Construction Manual, Fourth Edition - Mad Cad

Volume II DETERMINING SITE-SPECIFIC LOADS 8
EXAMPLE 8.2. WAVE SLAM CALCULATION
Given:
Find:
• Zone V building elevated on pile foundation near saltwater
• Bottom of floor beam elevation = 15.0 ft NGVD
• Length of beam (parallel to wave crest) = 50 ft
• Design stillwater elevation = 12.0 ft NGVD
• Eroded ground elevation = 5.0 ft NGVD
• C s (wave slam coefficient; see Equation 8.7) = 2.0
• w = specific weight of water (62.4 lb/ft3 for fresh water and 64.0 lb/ft 3 for saltwater)
• A = (8 ft)(0.833 ft) = 6.664 ft 2
1. Wave crest elevation
2. Vertical height of the beam subject to wave slam
3. Lateral wave slam acting on the elevated floor system
Solution for #1: The wave crest elevation can be calculated as 1.55 times the stillwater depth, above
the eroded ground elevation
Wave crest elevation = 5.0 ft NGVD + 1.55 (12.0 ft NGVD – 5.0 ft NGVD) = 15.9 ft NGVD
Solution for #2: The vertical height of the beam subject to wave slam can be found as follows:
Vertical height = wave crest elevation – bottom of beam elevation = 15.9 ft NGVD –
15.0 ft NGVD = 0.9 ft
Solution for #3: Using Equation 8-7, the lateral wave slam acting on the elevated floor system can be
found as follows:
COASTAL CONSTRUCTION MANUAL
8-27