Appendices 
111 
Combination factors for the superposition of wave, water current and ice occurrences are not 
listed in DIN EN 1990. As an alternative to the undiminished superposition of the individual 
occurrences listed, actions from the combined occurrence of waves, water currents and ice 
with a 50-year cycle may be used in the estimate. In order to superimpose the individual ac 
tions as per DIN EN 1990 [1], [2] by means of leading and accompanying actions, it is neces 
sary to ensure that an integral, action-related partial safety factor of at least 1.35 is adhered to 
for the normal or extreme action combination. 
Appendix 5-IV Application notes on DIN EN 1993-1-9 - fatigue verifications 
5-IV.1 General information and partial safety factors 
The verifications in the fatigue limit state shall always be conducted according to DIN EN 
1993-1-9 [6] using either the nominal stress concept or the structural stress concept. Which 
concept is used - damage tolerance or adequate safety margin against fatigue failure without 
any prior indication - depends particularly on the feasibility of planned periodic inspections. 
The partial safety factors y Mf shall be selected accordingly along the lines of [6] from Table 
5-IV.1. 
Accessibility/execution of periodic 
inspections 
Damage tolerant or minor 
damage 
Not tolerant to damage or 
major damage 
Good accessibility, periodic 
inspections 
1.00 
1.15 
No or poor accessibility, no periodic 
inspections* 
1.15 
1.35 
* It shall be assumed that the accessibility to all components which are permanently under water is poor, for example. 
Table 5-IV.1: Partial safety factors in the fatigue verification 
Contrary to what is stated in the regulations in [6], a threshold value for the fatigue strength 
shall not be used when the number of load cycles N > 10 8 . 
In contrast to what is stated in [6], the recommendations of MW [15] Section 3.5.2.1. state that 
the dependence of the fatigue strength on effects of the metal sheet thickness should be ta 
ken into account. 
Using the notch detail definitions according to [6] assumes that all components have a func 
tioning corrosion protection system. The requirements in accordance with chapters B2.2.1, 
B2.3.1 and Annex 6 shall be complied with in this case. Depending on the achievable lifetime 
of the corrosion protection, the design shall include allowances to the calculated metal sheet 
thicknesses in the vicinity of the splash zone. 
In addition, the regulations of DNV [17] may be used for the fatigue verification. This can be 
particularly useful when there is no comprehensive corrosion protection as stated above and 
the correspondingly modified stress number curves are used. 
5-IV.2 Structural stress concept 
The fatigue verifications for welded nodes of hollow sections can be conducted solely accor 
ding to the structural stress concept. The stress concentration factors required for this shall 
be determined separately for all verification points with the aid of finite element calculations or 
from parametric equations. Relevant notes, e. g. [15] Section 2.2.3.4, can be obtained to ext-