Section 8 Open Floors

801. Arrangements

Where the double bottom is framed transversely, open floors are to be provided at every hold frame between solid floors in accordance with the requirements in this section.

802. Scantlings of frames and reverse frames

1. The section modulus of frames is not to be less than obtained from the following formula, but in no case is it to be less than 30 cm3.

ᾎ

Ě Ņ ǼĊᾜᾨ Ī (cm3)

where:

ᾨ = Distance between the brackets attached to the centre girder and the margin p1ate (m).

Where side girders are provided, ᾨ is the greatest on side girders and the brackets. (See Fig 8.1).

Ċ = Spacing of frames (m).

ᾜ = As obtained from the following formula (m).

distance between the vertical stiffeners

ᾜ Ņ ᾘ Ñ LǾLĪĴ Ã (m)

Ǽ = As specified in Table 8.2.

Table 8.2 Coefficient Ǽ

2. The section modulus of reverse frames is not to be less than obtained from the formula in Par 1 with Ǽ equal to 0.85 times the value specified for frames at the same location. Where no vertical strut is provided to the open floors under deep tanks, the scantling of reverse frames is not to be less than required in Ch 15, 202. taking the frames as the stiffener of deep tank bulkhead.

803. Vertical struts

1. Vertical struts prescribed in 802. are to be rolled sections other than flat bars and bulb plates and to be well overlapped with the webs of frames and reverse frames.

2. The sectional area of vertical struts is not to be less than that specified in 503. with necessary modifications.

804. Brackets

1. Frames and reverse frames are to be connected to the centre girder and margin plates by brackets of not less thickness than obtained from the formula in 205. 2.

2. The breadth of brackets specified in Par 1 is not to be less than 0.05Æ and the brackets are to be well over-lapped with frames and reverse frames. The free edges of brackets are to be properly stiffened.