fundamentals of engineering supplied-reference handbook - Ventech!

Specific Energy Diagram
y
1
1
2
αV
E =
2g
+ y
Alternate depths: depths with the same specific energy.
Uniform flow: a flow condition where depth and velocity
do not change along a channel.
Manning's Equation
K 2 3 1 2
Q = AR S
n
Q = discharge (m 3 /s or ft 3 /s),
K = 1.486 for USCS units, 1.0 for SI units,
A = cross-sectional area of flow (m 2 or ft 2 ),
R = hydraulic radius = A/P (m or ft),
P = wetted perimeter (m or ft),
S = slope of hydraulic surface (m/m or ft/ft), and
n = Manning’s roughness coefficient.
Normal depth (uniform flow depth)
2 3 Qn
AR =
1 2
KS
Weir Formulas
Fully submerged with no side restrictions
Q = CLH 3/2
V-Notch
Q = CH 5/2 , where
Q = discharge (cfs or m 3 /s),
C = 3.33 for submerged rectangular weir (USCS units),
C = 1.84 for submerged rectangular weir (SI units),
C = 2.54 for 90° V-notch weir (USCS units),
C = 1.40 for 90° V-notch weir (SI units),
L = weir length (ft or m), and
H = head (depth of discharge over weir) ft or m.
Hazen-Williams Equation
V = k1CR 0.63 S 0.54 , where
C = roughness coefficient,
k1 = 0.849 for SI units, and
k1 = 1.318 for USCS units,
R = hydraulic radius (ft or m),
S = slope of energy grade line,
= hf /L (ft/ft or m/m), and
V = velocity (ft/s or m/s).
137
CIVIL ENGINEERING (continued)
Values of Hazen-Williams Coefficient C
Pipe Material C
Concrete (regardless of age)
Cast iron:
130
New 130
5 yr old 120
20 yr old 100
Welded steel, new 120
Wood stave (regardless of age) 120
Vitrified clay 110
Riveted steel, new 110
Brick sewers 100
Asbestos-cement 140
Plastic 150
For additional fluids information, see the FLUID
MECHANICS section.
TRANSPORTATION
U.S. Customary Units
a = deceleration rate (ft/sec 2 )
A = algebraic difference in grades (%)
C = vertical clearance for overhead structure (overpass)
located within 200 feet of the midpoint of the curve
e = superelevation (%)
f = side friction factor
± G = percent grade divided by 100 (uphill grade"+")
h1 = height of driver's eyes above the roadway surface (ft)
h2 = height of object above the roadway surface (ft)
L = length of curve (ft)
Ls = spiral transition length (ft)
R = radius of curve (ft)
S = stopping sight distance (ft)
t = driver reaction time (sec)
V = design speed (mph)
Stopping Sight Distance
S =
V
⎛⎛ a ⎞ ⎞
30 ⎜⎜ ⎟ ± G
⎝⎝32.2⎠ ⎟
⎠
2
+ 1.47Vt