3.1. Coupling with hull girder horizontal bending
When a ship collides with the midship region of a struck ship, the global hull
girder horizontal bending (HGHB) of maximal level occurs in a struck ship as well as
the local compression and stretching. It is to be noted that the horizontal stringers of
a struck ship at the collided side is exposed to the global compression in longitudinal
direction as well as the local compression in transverse direction and local stretching
in longitudinal direction. It is also to be noted that the side shell in way of the struck
area is exposed to the global compression as well as the local stretching in
longitudinal direction, while the side shell above and below the struck area is
exposed to the global compression in addition to the local compression in
longitudinal direction. The local compression occurs partly to resist the local
stretching in way of the struck area.
Figs. 1–3 show the significant effect of the HGHB in the case that a VLCC collides
with a purpose-built ship for the transport of the irradiated nuclear fuels (INF ship).
The global bend and the change in the duration of contact force can be observed
although the safety of the cargo hold is secured in any case. INF ships, which
transport spent nuclear fuels, plutonium (MOX) and/or vetrified high-level
radioactive wastes within Japanese territorial waters must comply with Japanese
domestic regulation. In order to meet the requirements equivalent to that of the
nuclear-powered ships, such rather small ships (o100m in length) must be specially
built with the collision-resistant hull structure. The width of each double side space
(P&S) must be 1/5 or above of the ship’s beam and the double side structure must
have sufficient strength and energy absorption capability. Usually, heavy side
stringers (collision flats) are arranged closely at intervals of about 1.5–2.0m as well
as heavy upper deck and inner bottom.
On the other hand, Figs. 4–6 show the slight effect of the HGHB in the case that a
6200 TEU containership collides with the identical INF ship [4]. Some buckling