A7.5.1 Safety philosophy according to Eurocode 1997

Table A7-9 and table A7-10 present the relevant partial factors in accordance with the Eurocodes. However, recommendations for flexible dolphin are lacking. As a result, a set of partial safety factors specifically for flexible dolphins needed to be selected. The best fit is assumed to be a set of partial load and resistance factors, which complies with Design Approach 3 (DA3) and is in accordance with the currently used Dutch safety philosophy. Before the Eurocode, no partial safety factors were applied to geotechnical model parameters of flexible dolphins in the Netherlands. It should be noted that the interpretation of the safety philosophy according to Eurocode 1997, as described below, is applicable only to the comparison made in this chapter.

Table A7-9 Partial factors on load effects in conformity with Eurocode 1997, table A.3 [A7.4].

Load		Symbol	Combination
			A1	A2
				Other	Sheet piling
Permanent	Unfavourable	$γ_{G}$	1.35	1.0	1.0
	Favourable		0.9	1.0	1.0
Variable	Unfavourable	$γ_{Q}$	1.5	1.3	1.1
	Favourable		0	0	0

Combination A1 is applied to loads acting on a geotechnical structure. The nature of the loads arising from mooring and berthing impact is included in this combination.

Table A7-10 Partial factors on soil properties in conformity with Eurocode 7, table A.4a.

Soil parameter	Symbol	Combination
		M2
		Foundation on steel and piles	Retaining wall	Embankment
				Reliability class
				RC1	RC2	RC3
Angle of internal friction a)	$γ_{ϕ}$	1.15	1.2	1.2	1.25	1.3
Effective cohesion	$γ_{c'}$	1.6	1.5	1.3	1.45	1.6
Undrained shearing strength	$γ_{c u}$	1.35	1.5	1.5	1.75	2.0
Unconfined strength	$γ_{q u}$	1.35	1.5	1.5	1.75	2.0
Density weight	$γ_{γ}$	1.1	1.1	1.0	1.0	1.0
a) This factor is should be applied to tan $ϕ'$ .

In this analysis, partial safety factors recommended for 'retaining walls' were used, because the failure mechanism 'insufficient passive soil resistance' most closely resembles the failure mechanism of a horizontally loaded flexible dolphin. However, it was assumed that the partial factor

γ_{γ}

= 1.1 is not suitable for flexible dolphins and was set to

γ_{γ}

= 1.0.

For an accidental limit state, all partial factors are assumed to be equal to 1.0. For a fendering and berthing structure, a ship collision or an exceptionally high berthing impact load is an accidental design situation. It should be noted that this is not the same as abnormal berthing. Abnormal berthing represents an uncontrolled berthing procedure and should be considered a fundamental ULS design situation. Here, a factor of safety according to PIANC in the range of 1.25 to 2.0 has been used on berthing energy, particularly to take into account berthing frequency and variation in berthing velocity. The following table provides a summary of the conditions for flexible dolphins equipped with a fender system to be assessed. The most important variable loads are the berthing and mooring loads.

Table A7-11 Summary set partial load and resistance factors for dolphins complying with EN 1997 - Table A.4a.

	SLS		ULS
	Load factor	Resistance factor	Load factor	Resistance factors
1. Energy absorption	1.0	tan $ϕ$ / 1.0 c' / 1.0	1.0	tan $ϕ$ / 1.0 c' / 1.0
2a. Berthing load (STR/GEO)	1.0	tan $ϕ$ / 1.0 c' / 1.0	1.5*	tan $ϕ$ / 1,2 c' / 1.5
2b. Mooring load (STR/GEO)	1.0	tan $ϕ$ / 1.0 c' / 1.0	1.5	tan $ϕ$ / 1,2 c' / 1.5
* The load factor is only applicable to the berthing and mooring force.

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A7.5.1 Safety philosophy according to Eurocode 1997