Symbols

For symbols not defined in this section, refer to Ch 1, Sec 4.

A_s : Net sectional area of the stiffener without attached plating, in mm².

a : Length of the longer side of the plate panel, in mm.

b : Length of the shorter side of the plate panel, in mm.

b_eff : Effective width of the attached plating of a stiffener, in mm, as defined in [2.3.5].

b_eff1 : Effective width of the attached plating of a stiffener, in mm, without the shear lag effect taken as:

For σ_x > 0
- For prescriptive assessment:
- For FE analysis:
  
  b_eff₁ = C_xb
For σ_x ≤ 0

b_eff₁ = b

b_f : Breadth of the stiffener flange, in mm.

b₁, b₂ : Width of plate panel on each side of the considered stiffener, in mm.

C_x1,C_x2 : Reduction factor defined in Table 3 calculated for the EPP1 and EPP2 on each side of the considered stiffener according to case 1.

d : Length of the side parallel to the axis of the cylinder corresponding to the curved plate panel as shown in Table 4, in mm.

d_e : Distance from upper edge of web to the top of the flange, in mm, as defined in Ch 3, Sec 2, Figure 3.

e_f : Distance from attached plating to centre of flange, in mm, as shown in Figure 1 to be taken as:

e_f = h_w for flat bar profile.
e_f = h_w – 0.5 t_f for bulb profile.
e_f = h_w + 0.5 t_f for angle, L2 and Tee profiles.
e_f = h_w − d_e − 0.5 t_f for L3 profile.

F_long : Coefficient defined in [2.2.4].

F_tran : Coefficient defined in [2.2.5].

h_w : Depth of stiffener web, in mm, as shown in Figure 1.

: Span, in mm, of stiffener equal to spacing between primary supporting members or span of side frame equal to the distance between the hopper tank and top wing tank as defined in Pt 2, Ch 1, Sec 2, Figure 2.

R : Radius of curved plate panel, in mm.

R_{eH_P} : Specified minimum yield stress of the plate in N/mm².

R_{eH_S} : Specified minimum yield stress of the stiffener in N/mm².

S : Partial safety factor to be taken as

S = 1.1 for structures which are exposed to local concentrated loads (e.g. container loads on hatch covers, foundations).
S = 1.15 for bulk carrier stiffeners located on the hatchway coamings, the sloping plate of the topside and hopper tanks, the inner bottom, the inner side if any, the side shell of single side skin construction and the top and bottom stools of transverse bulkheads.
S = 1.0 for all other cases.

t_p : Net thickness of plate panel, in mm.

t_w : Net stiffener web thickness, in mm.

t_f : Net flange thickness, in mm.

x axis : Local axis of a rectangular buckling panel parallel to its long edge.

y axis : Local axis of a rectangular buckling panel perpendicular to its long edge.

α : Aspect ratio of the plate panel, defined in Table 3 to be taken as:

β : Coefficient taken as:

ω : Coefficient taken as:

ω = min (3;α)

σ_x : Stress applied on the edge along x axis of the buckling panel, in N/mm².

σ_y : Stress applied on the edge along y axis of the buckling panel, in N/mm².

σ₁ : Maximum stress, in N/mm².

σ₂ : Minimum stress, in N/mm².

σ_E : Elastic buckling reference stress, in N/mm² to be taken as:

For the application of plate limit state according to [2.2.1]:
For the application of curved plate panels according to [2.2.6]:

τ : Applied shear stress, in N/mm².

τ_c : Buckling strength in shear, in N/mm², as defined in [2.2.3].

ψ : Edge stress ratio to be taken as:

γ : Stress multiplier factor acting on loads. When the factor is such that the loads reach the interaction formulae, γ = γ_c.

γ_c : Stress multiplier factor at failure.

Figure 1: Stiffener cross sections