Page 109 - Marine Structural Design
P. 109
Chapter 4 Scantling of Ship’s Hulls &Rules 85
(4.28)
The critical compressive buckling stress, e,, is given by the equation below:
(4.30)
The elastic shear buckling stress, ze , is calculated similarly. The critical buckling shear stress
is given by the following equations:
z
z, = ref for ref < 2 (4.31)
2
(4.32)
where, rei, is the ideal elastic shear buckling stress and z, , is the yield stress in shear of
material in N / mm2 , which is given by: ry = o /& .
Buckling Evaluation
Design codes with respect to buckling strength are developed based on the above mentioned
formulae. The following interaction formula may be used to calculate buckling of plates under
combined compression and shear stress (Bannerman and Jan, 1980):
($1 +[tJ 51.OlS.F (4.33)
where e and zdenote the predicted maximum compressive stress (due to axial compression
and bending), and the predicted average shear stress respectively. a,and z, are the critical
buckling stress corresponding to axial compressionhending and corresponding to pure shear
loading respectively. S. F. is the safety factor.
4.5.5 Buckling of Profiles
Axially compressed profiles (longitudinal) should be evaluated to withstand the following
buckling modes:
Lateral buckling mode
Torsional buckling mode
Web and flange buckling mode
Transverse stiffeners and girders require special considerations.
The Elastic Buckling Stress will be discussed below.
Lateral buckling mode:
