Section
12 Pillars and pillar bulkheads
12.1 Application
12.3 Design loads
12.3.1 The
design loading, L
pi, to be used in the determination
of pillar scantlings is as follows:
|
L
pi
|
= |
S
gt
b
gt
P
c + L
a kN
|
where
|
L
pi
|
= |
design load supported by the pillar, to be taken as not less
than 5 kN |
|
P
c
|
= |
basic deck girder design pressure, as appropriate, plus any
other loadings directly above the pillar, in kN/m2
|
|
L
a
|
= |
load from pillar or pillars above, assumed zero if there are
no pillars over, in kN |
|
S
gt
|
= |
spacing, or mean spacing, of girders or transverses, in metres |
|
b
gt
|
= |
distance between centres of two adjacent spans of girders or
transverses supported by the pillar, in metres. |
12.4 Scantling determination
12.4.2 The
cross-sectional area of the pillar, A
p, is
not to be less than:
where
|
σ
p
|
= |
permissible compressive stress, in N/mm2
|
| = |
|
where
|
σ
o
|
= |
specified minimum yield strength of the material, in N/mm2
|
|
C
f
|
= |
pillar end fixity factor |
| = |
0,25 for full fixed/bracketed |
| = |
0,50 for partially fixed |
| = |
1,0 for free ended |
|
r
|
= |
least
radius of gyration of pillar cross-section, in cm |
| = |
|
p
|
= |
least moment
of inertia of cross-section of pillar or stiffener/plate combination,
in cm4
|
Table 3.12.1 Pillar location factors
| Location
|
f
pi
|
| Supporting
weather deck
|
0,50
|
| Supporting
vehicle deck
|
0,50
|
| Supporting
stores equipment and routes
|
0,50
|
| Supporting
accommodation/inner deck
|
0,75
|
| Supporting deckhouse top
|
1,00
|
12.5 Slenderness ratio
12.5.1 The
slenderness ratio (
e/r) of pillars should not in general
exceed 1,1. Pillars with slenderness ratio in excess of 1,1 may be
accepted subject to special consideration on a case by case basis
and provided that the remaining requirements of the Rules are complied
with.
12.6 Pillars in tanks
12.6.1 The
tensile stress in the pillar and its end connections is not to exceed
108 N/mm2 at the tank test pressure.
12.7 Pillar bulkheads
12.7.2 The
cross-sectional area of the pillar bulkhead, A
pb,
is to be determined in accordance with Vol 1, Pt 6, Ch 3, 12.4 Scantling determination using the design loading, L
pb, as
follows:
|
L
pb
|
= |
S
pb
B
pb
P
c + L
c + L
p + L
a kN
|
where
|
L
pb
|
= |
design load supported by the stiffener plate combination of
the pillar bulkhead, to be taken as not less than 5 kN |
|
P
c
|
= |
basic deck girder design pressure, as appropriate, directly
above the pillar bulkhead, in kN/m2
|
|
L
c
|
= |
point loads applied to load area supported by the pillar bulkhead,
and not included in P
c, in kN Point loads
supported by the pillar bulkhead which should include point loads
within the load patch plus point loads from outside the load patch,
which distribute to the pillar bulkhead. Point loads which fall between
pillar bulkheads should be shared proportionately between support
points
|
|
L
p
|
= |
load resulting from uniformly distributed loads on decks above,
excluding the deck directly above, which have been carried through
by pillars or pillar bulkheads above, in kN |
|
L
a
|
= |
point load, in kN, from above |
|
|
= |
zero if there are
no pillars or pillar bulkheads over |
|
|
= |
65 per cent of
the point load from pillar bulkhead over, provided the pillar bulkhead
spans between primary support points |
|
|
= |
full load from
pillar or pillars over |
|
|
= |
full load from
pillar bulkhead or pillar bulkheads over that do not span between
primary support points |
|
S
pb
|
= |
spacing, or mean spacing, of bulkheads or effective transverses/longitudinal
stiffeners, in metres |
|
B
pb
|
= |
distance between centres of two adjacent spans of girders or
transverses supported by the pillar bulkhead, in metres, and can be
taken as the distance between pillar bulkhead stiffeners where the
stiffeners at the top of the bulkhead effectively distribute the load
evenly into the stiffeners. |
12.7.3 The
thickness of the bulkhead plating is in no case to be taken as less
than 4 mm
12.7.4 The
scantlings of the pillar bulkhead are not to be less than those of
any bulkhead or pillar bulkhead in the direct support line above that
being considered.
12.8 Direct calculations
12.9 Novel features
12.9.1 Where
unusual or novel pillars designs are proposed that are unable to comply
with the requirements of this Section, their design together with
the direct calculations are to be submitted for special consideration.
|