FEMA P55 Coastal Construction Manual, Fourth Edition - Mad Cad

8 DETERMINING SITE-SPECIFIC LOADS Volume II
EXAMPLE 8.3. HYDRODYNAMIC LOAD ON PILES VERSUS BREAKING WAVE LOAD
ON PILES
Given:
Find:
• Building elevated on round-pile foundation near saltwater
• C d (drag coefficient for nonbreaking wave on round pile; see Equation 8.8) = 1.2
• C db (drag coefficient for breaking wave on round pile; see Equation 8.5) = 1.75
• D = 10 in. or 0.833 ft
• d s = 8 ft
• Velocity ranges from 8 ft/sec to 16 ft/sec
• = mass density of fluid (1.94 slugs/ft 3 for fresh water and 1.99 slugs/ft 3 for saltwater)
• w = specific weight of water (62.4 lb/ft 3 for fresh water and 64.0 lb/ft 3 for saltwater)
• A = (8 ft)(0.833 ft) = 6.664 ft 2
1 The range of loads from hydrodynamic flow around a pile
2. Load from a breaking wave on a pile
Solution for #1: The hydrodynamic load from flow past a pile is calculated using Equation 8.8
as follows:
For a flood velocity of 8 ft/sec:
F nonbrkp = 509 lb/pile
For a flood velocity of 16 ft/sec:
F nonbrkp = 2,037 lb/pile
The range of loads from a nonbreaking wave: 509 lb/pile to 2,037 lb/pile
8-30 COASTAL CONSTRUCTION MANUAL