FLOOD06430

• County: Statewide
• Basin: Statewide
• Title: Conduits, Culverts and Pipes
• Date: 3/3/1969
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Educational/Technical/Reference Information

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EM 1110-2-2902
3 Mar 1969

C ~ C.. + C', + C'2 (where Co' = 0.85f',Db)

d" = Co' <D/2 - d') . C. (d - d')(moments about tens. reinf.)
C

x. = D/2 - d' - d" ~ to plastic centroid-see fig. 3)
Taking moments about the plastic centroid,
Td" + C,(D/2 + x. - a/2) + C.(D/2 + x. - d') - P,e, = 0
Solve this equation for "e,". If it is found to be less than He", the ultimate capacity is contro!led by
tension.

p.

b b
eb= A~/Pb d" d'
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centroid

c

Fig. 3. Typical Stres8 Diau,oam-Ultimate Strength Design, Balanced Condition

C, = N" + T - C. = 0.85f',ab

No + T - C. (' f N )
a = 0.85f',b In terms 0 0 - - - - - - - - - - -

10 = e - 0.5D + 0.5a (distance C, to No in tenns of a)

Taking moments about C"
Nul' - C. (0.5a - d') - T (d - 0.5a) = 0

N" = C.(O.s: ~ ~.~; :~~5: O.5a) _______________________________(24)

. _ __._ _ _ _ ._._ _ ____ _ _ _ __. _ _ _ _ _ _ _ (23)

Assume value of "a" and solve for No. Insert this value in equation for "a" above as a check
upon assumed value of "a". Nu represents an "ideal" value before applying the capacity reduction
factor, <p.

FS = <p No/N (use <p = 0.70 for most designs) _________________._________________(25)

The factor of safety should be close to 1.8 for economy.

c. Joints and Colmrs. Spacing of contraction joints generally should be limited to a maxi-

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