3 Stiffeners

3.1 Reference point

3.1.1 The requirements of section modulus for stiffeners relate to the reference point giving the minimum section modulus. This reference point is generally located as shown in Figure 24 for typical profiles.

3.2 Load calculation points

3.2.1 LCP for Pressure

The load calculation point for the pressure is located at:

• Middle of the full length, , of the considered stiffener.
• The intersection point between the stiffener and its attached plate.

For stiffeners located on transom plate, the y coordinate of the load calculation point is to be taken corresponding to y value at side shell at z level of the load calculation point, for the external dynamic pressure calculation.

Figure 24 : Reference point for calculation of section modulus and hull girder stress for local scantling assessment

3.2.2 LCP for hull girder bending stress

The load calculation point for the hull girder bending stresses is defined as follows:

• For yielding verification according Ch 6:

  • At the middle of the full length, , of the considered stiffener.
  • At the reference point given in Figure 24.
• For prescriptive buckling requirements according to Ch 8:

  • At the middle of the full length, , of the considered stiffener.
  • At the intersection point between the stiffener and its attached plate.

3.2.3 Non-horizontal stiffeners

The lateral pressure, P is to be calculated as the maximum between the value obtained at middle of the full length, , and the value obtained from the following formulae:

when the upper end of the vertical stiffener is below the lowest zero pressure level.

when the upper end of the vertical stiffener is at or above the lowest zero pressure level, see Figure 25.

where:

₁ : Distance, in m, between the lower end of vertical stiffener and the lowest zero pressure level.

P_U, P_L : Lateral pressures at the upper and lower end of the vertical stiffener span , respectively.

Figure 25 : Definition of pressure for vertical stiffeners