1 Cargo Hold Side Frames of Single Side Bulk Carriers

1.1 Strength criteria

1.1.1 Net section modulus and net shear sectional area

The net section modulus Z, in cm3, and the net shear sectional area A_shr, in cm², in the mid-span area of side frames subjected to lateral pressure are not to be taken less than:

where:

f_bdg : Bending coefficient taken as 10.

ℓ_B : Lower bracket length, in m, as defined in Figure 1.

P : Design pressures, in kN/m², for design load sets as defined in Pt 1, Ch 6, Sec 2, Table 1.

Figure 1 : Side frame lower bracket length

1.1.2 Side frames in ballast holds

In addition to [1.1.1], for side frames in cargo holds designed to carry ballast water in heavy ballast condition, the net section modulus Z, in cm³, and the net web thickness, t_w, in mm, all along the span are to be in accordance with Pt 1, Ch 6, Sec 5 where the span of the side frame is ℓ as defined in Pt 1, Ch 3, Sec 7, [1.1] with consideration to brackets at ends.

1.1.3 Additional strength requirements

The net moment of inertia I, in cm⁴, of the three side frames located immediately abaft the collision bulkhead is not to be taken less than:

where:

n : Frame number of considered side frame counted from the collision bulkhead to the frame in question, taken equal to 1, 2 or 3.

As an alternative, supporting structures, such as horizontal stringers, are to be fitted between the collision bulkhead and a side frame which is in line with transverse webs fitted in both the topside tank and hopper tank, maintaining the continuity of the forepeak stringers within the foremost hold.

1.2 Lower bracket of side frame

1.2.1 At the level of the lower bracket as shown in Ch 1, Sec 2, Figure 2, the net section modulus of the frame and bracket, or integral bracket, with associated shell plating, is not to be taken less than twice the required net section modulus Z, in cm³,for the frame mid-span area obtained from [1.1.1].

1.2.2 For holds intended to carry ballast water in heavy ballast condition, the net section modulus Z, in cm³, at the level of the lower bracket is not to be taken less than twice the greater of the required net section moduli given in [1.1.1] and [1.1.2].

1.2.3 The net thickness t_LB, in mm, of the lower bracket is not to be taken less than:

where t_w is the net thickness of the side frame web, in mm.

1.2.4 The net thickness t_LB of the lower bracket is to comply with the following formula:

• For symmetrically flanged frames:

• For asymmetrically flanged frames:

The web depth h_LB of lower bracket is to be measured from the intersection between the hopper tank sloping plating and the side shell plate, perpendicularly to the face plate of the lower bracket as shown in Ch 1, Sec 2, Figure 5.

For the three side frames located immediately abaft the collision bulkhead, where the frames are strengthened in accordance with [1.1.3] and the offered t_LB is greater than 1.73 t_w, the t_LB applied in [1.2.4] may be taken as t’_LB given by:

where t_w is the net thickness of the side frame web, in mm, corresponding to A_shr determined in accordance to [1.1.1].

1.3 Upper bracket of side frame

1.3.1 At the level of the upper bracket as shown in Ch 1, Sec 2, Figure 2 the net section modulus of the frame and bracket, or integral bracket, with associated shell plating, is not to be taken less than twice the net section modulus Z required for the frame mid-span area obtained from [1.1.1].

1.3.2 For holds intended to carry ballast water in heavy ballast condition, the net section modulus Z, in cm3, at the level of the upper bracket is not to be taken less than twice the greater of the required net sections modulus obtained from [1.1.1] and [1.1.2].

The net thickness t_UB of the upper bracket, in mm, is not to be less than the net thickness of the side frame web.

1.4 Provided support at upper and lower connections of side frames

1.4.1 Net section modulus

The net section modulus of the:

• Side shell and hopper tank longitudinals supporting the lower connecting brackets.
• Side shell and topside tank longitudinals supporting the upper connecting brackets.

is to comply with the following formula:

where:

n : Number of the longitudinal stiffeners on the side shell and hopper/topside tank supporting the lower/upper end connecting bracket of the side frame, as applicable.

Z_{pl i} : Net plastic section modulus, in cm³, of the i-th longitudinal stiffener on the side shell or hopper/topside tank supporting the lower/upper end connecting bracket of the side frame, as applicable.

d_i : Distance, in m, of the above i-th longitudinal stiffener from the intersection point of the side shell and hopper/topside tank.

ℓ₁ : Spacing, in m, of transverse supporting webs in hopper/topside tank, as applicable.

R_eH : Lowest value of specified yield stress, in N/mm², among the materials of the longitudinal stiffeners of side shell and hopper/topside tanks that support the lower/upper end connecting bracket of the side frame.

1.4.2 Net connection area of brackets

The net connection area of the lower or upper connecting bracket to the supporting longitudinal stiffener is to comply with the following formula:

where:

A_i : The offered net connection area of the bracket connecting with the i-th longitudinal stiffener, in cm².

d_i, α_τ : As defined in [1.4.1].

R_eH,hkt-i : The specified minimum yield stress of the bracket connecting with the i-th longitudinal stiffener, in N/mm²,

s : The space of the side frame, in mm.