Page 280 - Marine Structural Design
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256 Part I1 Ultimate Strength
(1 3.17)
where the ultimate stress at two sides of the plate, uL , is equal to the ultimate stress of a
square plate of width a, evaluated according to Carlsen (Fq. (13.9)). Finally, uWc is the
ultimate strength of a wide column. According to Smith (1981) it may be approximated by:
0.63
uwc = (1 3.1 8)
1 + 3.27- Wo ,ax
PL2t
where p, = 4 iy and W,,, denotes the maximum initial deflection of the wide column. In
the present study, the effective width of the plate is assumed to change until it reaches the
ultimate state in a similar manner to the effective width of a long plate:
(1 3.19)
where the coefficients c, and c2 can be determined from two points A and B in Figure 13.3.
b* t
Figure 13.3 Effective Width for a Wide Plate
The contribution of the plate to the beam-column's stiffness is updated every time a load is
added. The generalized ultimate plastic forces in compression, tension, and bending are
calculated using the corresponding ultimate reduction factors. A yield surface in the form of a
sphere is constructed based on these reduction factors. AEter yielding, the surface is kept
constant and the nodal forces will move along the surface following the plastic node method
(Ueda & Yao,1982).
