External Load Calculation for Buried Conduit

EXTERNAL LOAD CALCULATIONS FOR DIRECT BURIED CONDUIT
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3. CALCULATE THE PIPE STIFFNESS (PS)
PS = E*I/(0.149*r
3
) = [150,000 lb/in
2
*0.003 in
3
]/[0.149*(2.084 in)
3
] = 337.7 in
2
4. CALCULATE THE MAXIMUM LOAD FOR 5% DEFLECTION (W)
W = [∆∆
∆∆
X*(0.149*PS + 0.061*E
1
)]/(D*K) = [0.05*(0.149*333.7 lb/in
2
+0.061*1000
lb/in
2
)]/(1.5*0.1) = 36.9 lb/in
2
5. CALCULATE THE DEAD LOAD (DL)
DL = γγ
γγ
* H/144 = 120 lb/ft
3
*4 ft/144 = 3.33 lb/in
2
6. DETERMINE THE LIVE LOAD (LL) USING THE TABLE
LL = 2.78 lb/in
2
7. CALCULATE THE TOTAL LOAD (TL)
TL = DL + LL = 3.33 lb/in
2
+ 2.78 lb/in
2
= 6.11 lb/in
2
SINCE THE TOTAL LOAD OF 6.11 lb/in
2
IS LESS THAN THE MAXIMUM LOAD
OF 36.9 lb/in
2
THE 4” SDR 13.5 CONDUIT WOULD DEFLECT LESS THAN 5%.
DISCLAIMER:
THIS DOCUMENT IS FOR INFORMATIONAL PURPOSES ONLY. A
PROFESSIONAL ENGINEER SHALL BE RESPONSIBLE FOR ALL
SELECTIONS AND CALCULATIONS TO DETERMINE WHICH TYPE AND SIZE
OF CONDUIT OR DUCT SHALL BE USED.
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