In the special case like INF ships referred in Section 3.1, to which no primary
transverse is arranged and heavy primary horizontal stringers are arranged, the large
bulbous bow of a VLCC can contact full depth but relatively small side area of an
INF ship. Usually, the double bottom in cargo space is stiffened with longitudinals
and the transverse bulkhead is stiffened with vertical frames. As shown in Figs. 13
and 14, even the transverse bulkhead, cross deck and double bottom can collapse
and absorb the energy. Whole double side structure seems to move inboard into the
cargo hold space. In this case, the effective stretching span of the shells is longer
exceeding the spacing of the transverse bulkheads or the cargo hold length. When the
global strengths of the basic supporting structures are more critical than the local
strengths of the double side members, the effect of the HGHB may be eased because
of reduced contact force. On the other hand, other FEA, in which the supporting
effect of the heavy ‘tween deck structures of the INF ship was taken into account,
have shown quite different results. ‘Tween decks, seats, etc. are used to be neglected
in the structural modeling without reasonable consideration because of the
‘‘outfittings or equipments’’ which are out of the category of the main hull structure.