Clasification Society Rules and Regulations - Rules and Regulations for the Classification of Offshore Units, January 2016 - Part 10 SHIP UNITS - Chapter 2 Loads and Load Combinations - Section 4 Sloshing and impact loads
Section 4 Sloshing and impact loads
4.1 Sloshing loads
- When the partial filling of tanks is contemplated in operating conditions, the sloshing loads on tank boundaries are to be assessed in accordance with the LR ShipRight Procedure for Ship Units. Full account is to be taken of the operating requirements on station with regard to the filling, transfer and export operations for cargo bulk storage tanks.
4.2 Bottom slamming loads
- The slamming loads in this Section apply to units with
≥ 0,7 and bottom slamming draught ≥0,01L and
≤0,045L. For operation at deeper draughts, the slamming loads will
need to be specially considered.
- For units with unconventional bow shapes or for harsh service, the slamming loads, green sea loads and bow impact loads are to be determined by a site-specific analysis. The analysis results are to be verified by model tests.
- The bottom slamming pressure,
, is to be taken as the greater of:
= 
130g
kN/m2 for empty tanks
= 
130g
kN/m2 for full tanks
where
= longitudinal slamming distribution factor, see Pt 10, Ch 2, 4.3 Bow impact loads 4.3.2 = 0,0 at 0,5L = 1,0 at [0,175 – 0,5 ( 
– 0,7)] L from F.P. = 1,0 at [0,1 – 0,5 ( 
– 0,7)] L from F.P. = 0,5 at, and forward of, F.P. intermediate values to be obtained by linear interpolation
= environmental factor due to dynamic wave pressure. For
the initial design of units to be taken as that derived for the light load
draught in Pt 10, Ch 2, 3.4 Return periods and probability factor,
fprob
3.4.6
= block coefficient, 
, as defined in Pt 10, Ch 2, 3.1 Symbols, but not to be taken less
than 0,7 or greater than 0,8
= slamming coefficient for empty tanks
= 5,95 – 10,5 
= slamming coefficient for full tanks
= 5,95 – 10,5 
= 0,0 for L ≤ 180 m
= – 0,0125
for L > 180 m
= design slamming light load draught at F.P. with tanks
within the bottom slamming region empty, as defined in Pt 10, Ch 2, 4.2 Bottom slamming loads 4.2.2, in metres
= design slamming light load draught at F.P. with tanks
within the bottom slamming region full, as defined in Pt 10, Ch 2, 4.2 Bottom slamming loads 4.2.2, in metres
= dynamic load coefficient, to be taken as 1,25
L = Rule length, in metres
zball = vertical distance from tank top to load point, in
metres.
- The designer is to provide the design slamming
draughts
and 
.
- The design slamming draught at the F.P.,
, is not to be greater than the minimum draught at the F.P.
indicated in the loading manual for all transit conditions wherein the tanks
within the bottom slamming region are empty.
- The design slamming draught at the F.P.,
, is not to be greater than the minimum draught at the F.P.
indicated in the loading manual for any transit conditions wherein the tanks
within the bottom slamming region are full.
- The loading guidance information is to indicate clearly the design slamming draught.
4.3 Bow impact loads
- The bow impact pressure applies to the side structure in the area
forward of 0,1L aft of F.P. and between the waterline at draught
and the highest deck at side.
- The bow impact pressure,
, is to be taken as:
kN/m2
where
intermediate values to be obtained by linear interpolation
= environmental factor due to dynamic wave pressure
For the initial design of units to be taken as:
for the 
in Pt 10, Ch 2, 3.4 Return periods and probability factor,
fprob
3.4.6 for the pressure
calculation at the light load waterline
for the 
in Pt 10, Ch 2, 3.4 Return periods and probability factor,
fprob
3.4.6 for the pressure
calculation at and above the deep load waterline
For the pressure calculation in between
and 
, the factor is be obtained by interpolating between the 
factors for 
and for 
= impact speed, in m/s
For fixed locations, impact speed to be taken
as 5 sin
= local waterline angle at the position considered, but
is not to be taken as less than 35°, see
Pt 10, Ch 2, 4.3 Bow impact loads 4.3.2
= local bow impact angle measured normal to the shell
from the horizontal to the tangent line at the position considered, but is
not to be less than 50°, see
Pt 10, Ch 2, 4.3 Bow impact loads 4.3.2
= 1,0 for positions between draughts 
and 
=
for positions above draught
= vertical distance from the waterline at draught 
to the highest deck at side, see
Pt 10, Ch 2, 4.3 Bow impact loads 4.3.2, in metres
= vertical distance from the waterline at draught 
to the position considered, see
Pt 10, Ch 2, 4.3 Bow impact loads 4.3.2, in metres
L = Rule length, in metres
= scantling draught, in metres
= minimum design light draught, in metres
= waterline at the position considered, see
Pt 10, Ch 2, 4.3 Bow impact loads 4.3.2
Figure 2.4.1 Longitudinal distribution of slamming pressure
Figure 2.4.2 Definition of bow geometry
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