4 External Pressures on Superstructure and Deckhouses

4.1 Application

4.1.1 The external pressures on superstructure and deckhouses are only to be applied for strength assessment. These pressures are to be considered as dynamic pressures and are to be applied to the appropriate structure without any static pressure load component.

4.1.2 The dynamic load case concept is not to be applied for external pressures on superstructures and deckhouses.

4.2 Exposed wheel house tops

4.2.1 The lateral pressure for exposed wheel house tops, P_D, in kN/m², is to be taken as:

P_D = 12.5

4.3 Sides of superstructures

4.3.1 The design pressure for the external sides of superstructures, P_SI, in kN/m², is to be taken as:

where:

c_F : Distribution factor according to Table 32.

Table 32 : Distribution factor c_F

Location	*c_F*
x/L < 0.2	without taking x/L less than 0.1
x/L ≥ 0.2	1.0

4.4 End bulkheads of superstructures and deckhouse walls

4.4.1 The external pressure for the aft and forward external bulkheads of superstructures and deckhouse walls, in kN/m², is to be taken as:

P_A = f_n f_c [f_b f_d – (z_SD – T_SC)]

but is not to be less than P_A-min.

where:

f_n : Coefficient defined in Table 33.

f_c : Coefficient, to be taken as:

but not less than 0.475.
For exposed parts of machinery casings, f_c is not to be taken less than 1.0.

f_d : Coefficient, to be taken as:

for L < 150 m
for 150 m ≤ L < 300 m
f_d = 11.03 for L ≥ 300 m

b₁ : Breadth of deckhouse at the position considered.

B₁ : Actual breadth of ship on the exposed weather deck at the position considered.

f_b : Coefficient defined in Table 34.

P_A-min : Minimum lateral pressure, in kN/m², as defined in Table 35.

4 External Pressures on Superstructure and Deckhouses

Table 32 : Distribution factor cF

Table 32 : Distribution factor c_F