2 Structure Loaded By Steel Coils on Wooden Dunnage

2.1 General

2.1.1 The net thickness of inner bottom plating, hopper side plating and inner hull plating for ships intended to carry steel coils is to comply with [2.3.1] and [2.4.1] up to a height not less than the one corresponding to the top of upper tier in touch with hopper or inner hull plating.

The net section modulus and the net shear sectional area of longitudinal stiffeners on inner bottom, hopper tank top and inner hull for ships intended to carry steel coils are to comply with [2.3.2] and [2.4.2] up to a height not less than the one corresponding to the top of upper tier in touch with hopper or inner hull plating.

Standard terminology and means for securing of steel coils is described in Figure 2.

Figure 2 : Inner bottom loaded by steel coils

2.2 Load application

2.2.1 Design load sets

The static and dynamic load components are to be determined in accordance with Pt 1, Ch 4, Sec 7, Table 1.

Radius of gyration, k_r, and metacentric height, GM, are to be in accordance with Pt 1, Ch 4, Sec 3, Table 2 for the considered loading condition specified in the design load set. The design load sets for steel coil loading is given in Table 1.

Table 1 : Design load sets

Item	Design load set	Load component	Draught	Design load	Loading condition
Inner bottom, hopper sloping plate and inner hull	BC-9	F_sc-ib-s or F_sc-hs-s	T_SC	S	Steel Coil condition
Inner bottom, hopper sloping plate and inner hull	BC-10	F_sc-ib or F_sc-hs	T_SC	S+D	Steel Coil condition

2.3 Inner bottom

2.3.1 Inner bottom plating

The net thickness t, in mm, of plating of longitudinally framed inner bottom is not to be taken less than:

for design load set BC-9

for design load set BC-10

where:

K₁ : Coefficient taken as:

K₂ : Coefficient taken as:

C_a : Permissible bending stress coefficient, as defined in Pt 1, Ch 6, Sec 4, [1.1.1].

2.3.2 Stiffeners of inner bottom plating

The net section modulus Z, in cm³, and the net web thickness, t_w, in mm, of single span stiffeners located on inner bottom plating are not to be taken less than:

and for design load set BC-9.

and for design load set BC-10.

where:

K₃ : Coefficient as defined in Table 2.

K₃ = 2ℓ_bdg / 3, when n₂ > 10.

n₂ : Number of load points per EPP of the inner bottom, see Pt 1, Ch 4, Sec 6, [4.1.3].

Table 2: Coefficient K₃

n₂	1	2	3	4	5
K₃	ℓ _bdg

n₂	6	7	8	9	10
K₃

C_s : Permissible bending stress coefficient, as defined in Pt 1, Ch 6, Sec 5, [1.1.2].

C_t : Permissible shear stress coefficient for the design load set being considered, to be taken as:

C_t = 0.85 for acceptance criteria set AC-S.
C_t = 1.00 for acceptance criteria set AC-SD.

2.4 Hopper tank and inner hull

2.4.1 Hopper sloping plating and inner hull plating

The net thickness t, in mm, of plating of longitudinally framed bilge hopper sloping plate and inner hull is not to be taken less than:

, applicable for design load set BC-9.

, applicable for design load set BC-10.

where:

K₁ : Coefficient as defined in [2.3.1].

C_a : As defined in [2.3.1].

2.4.2 Stiffeners of hopper sloping plating and inner hull plating

The net section modulus Z, in cm³, and the net web thickness, t_w, in mm, of single span ordinary stiffeners located on bilge hopper sloping plate and inner hull plate are not to be taken less than:

and , applicable for design load set BC-9.

and , applicable for design load set BC-10.

where:

K₃ : Coefficient as defined in Table 2.

K₃ = 2ℓ_bdg / 3 , when n₂ > 10.

C_s, C_t : As defined in [2.3.2].

2 Structure Loaded By Steel Coils on Wooden Dunnage

Table 1 : Design load sets

Table 2: Coefficient K3

Table 2: Coefficient K₃