FLOOD03064

• County: Statewide
• Basin: Statewide
• Title: Evaluating Scour at Bridges
• Date: 11/1/1990
• Prepared By: Federal Highway Administration
• Floodplain - Doc Type: Floodplain Report/Masterplan

STEP 6, LOCAL SCOUR AT PIERS

pier 1 and 2
v, = 12.4 ft/s (12,4 X 1. 0)
Y, = 9.0 ft
Angle of attack = 00
Pie!!: 3
V, = 14.9 ft/s (12.4 X 1. 2)
Y, = 9.0 ft.
Angle of attack = 50
Problem 1.

Scour depth at pier 1 and 2.

Ys/Y,

= 2.0

K,

K2

(a/Y1) 0.65

Fr 0.43
,

Fr, = 12.4 1 (32,2 X 9,0)0.5 = 0.73
Ys 19,0 = 2.0 X 1.0 X 1.0 X (3 / 9.0)0.65 X (O.730.~3
Ys 19.0 = 0.86
Y s = 7.7 ft
Use Ys = 7.7 X 1.10 = 8.5 ft possible antidune flow.
Problem 2.

pier 3 Scour depth.

Fr, = 14.9 1 (32.2 X 9.0)0.5 = 0.88

Angle of attack Coefficient TABLE 4.3
L/a= 36 1 3 = 12, 0 = 50, Coefficient = 1.5
Ys 19.0 = 2.0 X 1.0 X 1.5 X (3 1 9.0)0.65 X (0.88)0.43
Ys 19.0 = 1.4

Ys = 12.5 ft
Use Ys = 12.5 X 1,10 = 13.8 ft Possible antidune flow.

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