Page 216 - Ship Construction.DJ Eyres 6Ed

Ch18-H8070.fm Page 205 Wednesday, October 18, 2006 6:58 AM
Bulkheads and Pillars 205
bulkhead. Substantial transverse cantilevers may also be fitted to support
the side decks. Pillars may also be fitted in holds on the ship’s centre line at
the hatch end, to support the heavy hatch end beams securely connected to
and supporting the hatch side girders. In a similar position it is not unusual
to find short corrugated fore and aft pillar bulkheads. These run from the
forward or aft side of the hatch opening to the adjacent transverse bulkhead
on the ship’s centre line.
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To maintain continuity of loading the tween pillars are arranged directly
above the hold pillars. If this is not possible stiffening arrangements should
be made to carry the load from the tween pillar to the hold pillar below.
sections to allow them to be welded externally. กพาณิชย์นาวี

PILLAR CONSTRUCTION It has already been seen that the hold pillar is
primarily subject to a compressive loading, and if buckling is to be avoided
in service the required cross-section must be designed with both the load
carried and length of pillar in mind. The ideal section for a compressive
strut is the tubular section and this is often adopted for hold pillars, hollow
rectangular and octagonal sections also being used. For economic reasons
the sections are fabricated in lengths from steel plate, and for the hollow
rectangular section welded channels or angles may also be used (see Figure
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18.6). A small flat bar or cope bar may be tack welded inside these pillar
Pillars have a bearing fit, and it is important that the loads at the head
and heel of the pillar should be well distributed. At the head of the pillar
a continuous weld is made to a doubling plate supported by brackets.
Details of the head fitting vary from ship to ship and depend very much
on the form of hatch side or deck girder which they support. The heel of
the hold pillar lands on a heavy doubling or insert plate at the tank top
and it is commonly arranged that the point of loading will coincide with
a solid floor/side girder intersection in the double bottom below. Where
this is not possible partial floors and short intercostal side girders may be
fitted to distribute the load.
Machinery space pillars are fabricated from angles, channels, or rolled
steel joists, and are heavily bracketed to suitably stiffened members
(Figure 18.7).
SMALL PILLARS Within the accommodation and in relatively small
vessels solid round steel pillars having diameters seldom exceeding 150mm
may be fitted. These may have forged palms at their head and heel, the
head being welded to a continuous angle fore and aft runner which sup-
ports the deck. Alternatively the pillar head may have a direct continuous
weld connection to an inverted angle beam or deck girder, with suitable
tripping brackets fitted directly above. The heel is then directly welded to
the deck which is suitably stiffened below (see Figure 18.8).