Page 104 - Marine Structural Design
P. 104
80 Part I Structural Design PrincipIes
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Figure 4.8 Individual Structural Members
Stiffeners
The minimum required stiffener size is specified by the section modulus of the stiffener as a
function of stiffener spacing, stiffener span, design pressure, and allowable stress.
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Figure 4.9 Stiffener
From the beam theory, the required section modulus of a stiffener is:
M
SM =- (4.12)
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Considering a stiffener with fixed ends, the maximum bending moment is:
M=412 (4.13)
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A stiffener is supposed to cany lateral pressure, which acts on the plate attached to the
stiffener, with a loading breadth equal to the stiffener spacing. Therefore, the distributed load
on the stiffener, q (in Nlmm), can be calculated from the following equation:
q=p*s (4.14)
where, s, is the stiffener spacing, and p, is the design pressure in N / mm’.
By inserting Eqs. (4.13) and (4.14) into Eq.(4.12), we obtain:
