FLOOD02929

• County: Statewide
• Community: na
• Basin: Statewide
• Title: Manufactured Home Installation in Flood Hazard Areas
• Date: 9/1/1985
• Prepared By: FEMA
• Floodplain - Doc Type: Educational/Technical/Reference Information

Drag rorces are calculated as follows:
Fd Cd x A x p X V2
= 2

Fd = Drag force in pounds

Cd = Coefficient of drag-1,31 for
a manufactured home

Q = Mass density of water-1,94
slugs per cubic foot

V = Floodwater velocity in feet
per second

A = Projected vertical area
submerged in square feet,
including the chassis I-beam

For example a 60 foot long manufactured home
submerged in six inches of water having a velocity
of five feet per second acting on the side of the
manufactured home chassis I-beam, as shown in
Figure 4,9, would be impacted by the following
drag force:

F _ 1.31 x (60 x 0.5) x 1.94 x (5)2 = 953 pounds
d- 2

Where:

Note that the bottom of the chassis I-beam
is the point at which drag forces initially occur,
Since the drag force is uniform over the side of

Table 4.3

Figure 4.9 Drag Force

the manufactured home, the drag force per square
foot can be determined as follows:

953 pounds
(60 ft, x 0.5 ft,) = 31,77 psf,

Table 4,3 provides drag forces as a function of
water velocity and height. Areas in the table where
drag forces exceed the capability of a manufac-
tured home design are shaded,
.:.~

DRAG FORCES (Fdl
(pounds per linear foot of hane length)

y Waler lie! ht In.
(Ips 2 3 4 5 6 9 12 15 18 24 30 36 48
1.0 .11 .21 .32 .42 .53 .64 .95 t.27 1.59 1.91 2.54 3.18 3.81 5.08
2.0 .42 .85 1.27 1.69 2.12 2.54 3.81 5.08 6.35
3.0 .95 1.91 2.86 3.81 4..77 5.72
4.0 1.69 3.39 5.08 6.78
5.0 2.85 5.29
6.0 3.81
8.0

F d = 1.31 x A x 1.94 x y2 (lb./lln. ft. of home)
2

Where: A = projected submerged vertical area in square feet
V = floodwater velocity in feet per second

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