Clasification Society Rulefinder 2020 - Version 9.33 - Fix
Common Structural Rules - Common Structural Rules for Bulk Carriers and Oil Tankers, January 2019 - Part 1 General Hull Requirements - Chapter 4 Loads - Section 2 Dynamic Load Cases - 3 Dynamic Load Cases for Fatigue Assessment

3 Dynamic Load Cases for Fatigue Assessment

3.1 Description of dynamic load cases

3.1.1 Table 7 to Table 9 define the ship motions responses and the global loads corresponding to each dynamic load case to be considered for fatigue assessment.

Table 7 : Ship responses for HSM and FSM load cases - Fatigue assessment

Load case HSM-1 HSM-2 FSM-1 FSM-2
EDW HSM FSM
Heading Head Following
Effect Max. bending moment Max. bending moment
VWBM Sagging Hogging Sagging Hogging
VWSF Negative–aft
Positive–fore 		Positive–aft
Negative–fore 		Negative–aft
Positive–fore 		Positive–aft
Negative–fore
HWBM - - - -
TM - - - -
Surge To stern To bow To bow To stern
asurge
Sway - - - -
asway - - - -
Heave Down Up - -
aheave - -
Roll - - - -
aroll - - - -
Pitch Bow down Bow up Bow up Bow down
apitch

Table 8 : Ship responses for BSR and BSP load cases - Fatigue assessment

Load case BSR-1P BSR-2P BSR-1S BSR-2S BSP-1P BSP-2P BSP-1S BSP-2S
EDW BSR BSR BSP BSP
Heading Beam Beam
Effect Max. roll Max. pressure at waterline
VWBM Sagging Hogging Sagging Hogging Sagging Hogging Sagging Hogging
VWSF Negative–aft
Positive–fore 		Positive–aft
Negative–fore 		Negative–aft
Positive–fore 		Positive–aft
Negative–fore 		Negative–aft
Positive–fore 		Positive–aft
Negative–fore 		Negative–aft
Positive–fore 		Positive–aft
Negative–fore
HWBM Stbd tensile Port tensile Port tensile Stbd tensile Stbd tensile Port tensile Port tensile Stbd tensile
TM - - - - - - - -
Surge - - - - - - - -
asurge - - - - - - - -
Sway To starboard To portside To portside To starboard To portside To starboard To starboard To portside
asway
Heave Down Up Down Up Down Up Down Up
aheave
Roll Portside down Portside up Starboard down Starboard up Portside down Portside up Starboard down Starboard up
aroll
Pitch - - - - - - - -
apitch - - - - - - - -

Table 9 : Ship responses for OST load cases - Fatigue assessment

Load case OST-1P OST-2P OST-1S OST-2S
EDW OST
Heading Oblique
Effect Max. torsional moment
VWBM Sagging Hogging Sagging Hogging
VWSF Negative–aft
Positive–fore 		Positive–aft
Negative–fore 		Negative–aft
Positive–fore 		Positive–aft
Negative–fore
HWBM Port tensile Stbd tensile Stbd tensile Port tensile
TM
Surge To bow To stern To bow To stern
asurge
Sway - - - -
asway - - - -
Heave Up Down Up Down
aheave
Roll Portside down Portside up Starboard down Starboard up
aroll
Pitch Bow up Bow down Bow up Bow down
apitch

3.2 Load combination factors

3.2.1 The load combinations factors, LCFs for the global loads and inertial load components for fatigue assessment are defined in:

Table 10: LCFs for HSM and FSM load cases.

Table 11: LCFs for BSR and BSP load cases.

Table 12: LCFs for OST load case.

Table 10 : Load combination factors, LCFs for HSM and FSM load cases - Fatigue assessment

Load component LCF HSM-1 HSM-2 FSM-1 FSM-2
Hull girder loads MWV CWV -1 1 -0.75 – 0.2fT 0.75 + 0.2fT
QWV CQW -1.0 flp 1.0 flp (-0.75-0.2fT) flp (0.75+0.2fT) flp
MWH CWH 0 0 0 0
MWT CWT 0 0 0 0
Longitudinal accelerations asurge CXS 0.3 – 0.2fT 0.2 – 0.3fT -0.4fT + 0.2 0.4fT - 0.2
apitch-x CXP -0.9 0.9 0.1 -0.1
gsinϕ CXG 0.4fT + 0.4 -0.4fT + -0.4 -0.15 0.15
Transverse accelerations asway CYS 0 0 0 0
aroll-y CYR 0 0 0 0
gsinθ CYG 0 0 0 0
Vertical accelerations aheave CZH 0.8fT - 0.15 0.15 – 0.8fT 0 0
aroll-z CZR 0 0 0 0
apitch-z CZP -0.9 0.9 0.1 -0.1

Table 11 : Load combination factors, LCFs for BSR and BSP load cases - Fatigue assessment

Load component LCF BSR-1P BSR-2P BSR-1S BSR-2S
Hull girder loads MWV CWV 0.1 – 0.2fT 0.2fT - 0.1 0.1 – 0.2fT 0.2fT - 0.1
QWV CQW (0.1–0.2fT) flp (0.2fT - 0.1) flp (0.1–0.2fT) flp (0.2fT - 0.1) flp
MWH CWH 1.1 – fT fT - 1.1 fT - 1.1 1.1 – fT
MWT CWT 0 0 0 0
Longitudinal accelerations asurge CXS 0 0 0 0
apitch-x CXP 0 0 0 0
gsinϕ CXG 0 0 0 0
Transverse accelerations asway CYS 0.2 – 0.2fT 0.2fT - 0.2 0.2fT - 0.2 0.2 – 0.2fT
aroll-y CYR 1 -1 -1 1
gsinθ CYG -1 1 1 -1
Vertical accelerations aheave CZH 0.7 – 0.4fT 0.4fT - 0.7 0.7 – 0.4fT 0.4fT - 0.7
aroll-z CZR 1 -1 -1 1
apitch-z CZP 0 0 0 0
Load component LCF BSP-1P BSP-2P BSP-1S BSP-2S
Hull girder loads MWV CWV 0.3 – 0.8fT 0.8fT - 0.3 0.3 – 0.8fT 0.8fT - 0.3
QWV CQW (0.3–0.8fT) flp (0.8fT - 0.3) flp (0.3–0.8fT) flp (0.8fT - 0.3) flp
MWH CWH 0.6 – 0.6fT 0.6fT - 0.6 0.6fT - 0.6 0.6 – 0.6fT
MWT CWT 0 0 0 0
Longitudinal accelerations asurge CXS 0 0 0 0
apitch-x CXP 0 0 0 0
gsinϕ CXG 0 0 0 0
Transverse accelerations asway CYS -0.95 0.95 0.95 -0.95
aroll-y CYR 0.3 -0.3 -0.3 0.3
gsinθ CYG -0.2 0.2 0.2 -0.2
Vertical accelerations aheave CZH 1 -1 1 -1
aroll-z CZR 0.3 -0.3 -0.3 0.3
apitch-z CZP 0 0 0 0

Table 12 : Load combination factors, LCFs for OST load cases - Fatigue assessment

Load component LCF OST-1P OST-2P OST-1S OST-2S
Hull girder loads MWV CWV -0.4 0.4 -0.4 0.4
QWV CQW -0.4 flp 0.4 flp -0.4 flp 0.4 flp
MWH CWH -0.9 0.9 0.9 -0.9
MWT CWT - flp-OST flp-OST flp-OST - flp-OST
Longitudinal accelerations asurge CXS -0.25 + 0.2fT 0.25 - 0.2fT -0.25 + 0.2fT 0.25 - 0.2fT
apitch-x CXP 0.4 - 0.2fT -0.4 + 0.2fT 0.4 - 0.2fT -0.4 + 0.2fT
gsinϕ CXG -0.4 + 0.2fT 0.4 - 0.2fT -0.4 + 0.2fT 0.4 - 0.2fT
Transverse accelerations asway CYS 0 0 0 0
aroll-y CYR -0.4 + 0.6fT 0.4 - 0.6fT 0.4 - 0.6fT -0.4 + 0.6fT
gsinθ CYG 0.2 - 0.3fT -0.2 + 0.3fT -0.2 + 0.3fT 0.2 - 0.3fT
Vertical accelerations aheave CZH -0.05 0.05 -0.05 0.05
aroll-z CZR -0.4 + 0.6fT 0.4 - 0.6fT 0.4 - 0.6fT -0.4 + 0.6fT
apitch-z CZP 0.4 - 0.2fT -0.4 + 0.2fT 0.4 - 0.2fT -0.4 + 0.2fT
Parent topic: Section 2 Dynamic Load Cases
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