design life, with a 10 % probability of excess during the life of the facility can be used. Similarly, a ground
acceleration of 0.2 times g in the reclaimed soils to account for soil amplification can be used.
9.4.8
Soil Pressure/Earth Loads
Lateral earth loads on waterfront structures and seawalls should be obtained by consideration of the soil
parameters for the in-situ soil and/or backfill against the structure.
Earth-retaining structures should be designed for a minimum surcharge load equal to the uniformly
distributed load used for the design of the adjacent deck. For seawalls with no associated wharf deck,
the minimum surcharge should be 5.0 kN/m². Where the area behind seawalls is subject to vehicle or
other heavy loads, the surcharge should be increased in accordance with relevant standards. Use of
relieving slabs may be required to improve the stability of the earth-retaining structures.
Consideration should be given to the effects of lateral water pressure (e.g. due to differences in water
levels between the waterside and the landside of vertical retaining walls) in conjunction with lateral earth
loads, in accordance with section 9.4.3.
9.5
Vessel Loads
9.5.1
Berthing Loads (Ship Impact)
The berthing impact load is subject to the approach velocity of a vessel which is mainly influenced by
wind, current and waves acting on the vessel at the time of berthing.
The berthing force shall be derived from the impacting energy on the structure and restraining system,
based on the design vessel striking the structure at a perpendicular velocity.
The effect of berthing impact loads shall be considered at both high and low tide. At low tide the pile
loading is likely to be the dominant effect. At high tide, the effect of the pile deflection on the structure is
likely to be dominant. The hydrodynamic mass shall be taken into account and berthing energy shall be
determined for mid-point berthing.
The impact load on the berth shall be determined as a function of the mass of the largest berthing vessel,
its berthing velocity and the spring properties of the berth.
The impact force is the force component of the berthing impact acting perpendicular on the berth.
If there are explicit spring elements (compression springs, fenders, etc.) the vessel berthing impact shall
be calculated as follows:
Equ. 6
Where:
vessel berthing impact (kN)
total range of spring (m)
berthing velocity (m/s)
mass (t) as the sum of vessel mass and hydrodynamic mass
Equ. 7
mass of vessel (displacement) (t)
hydrodynamic mass (t)
Chapter 4.4 includes further information regarding displacement of vessels.
If no other information about the design vessel is available, the mass of the vessel can be determined
according to Figure 4-5 in chapter 4 or from the following table as a result of related statistical
investigation:
24
Length (m)
Displacement (t)
7
8
10
12
15
18
20
22
25
28
30
32
35
38
40
2.6
3.7
6.4
10.1
17.6
27.7
36.1
45.7
62.9
83.5
99.2
116.5
145.6
178.8
203.2
Table 9.9-4
Displacement to Length Overall Relationships
The hydrodynamic mass shall be calculated with the following equation:
Equ. 8
with the following coefficients:
k1
2.0
2.5
3.0
3.5
4.0
4.5
5.0
1.20
1.00
0.86
0.75
0.66
0.60
0.55
Table 9.9-5
k2
Factor
as a function of the width-draught ratio B/T
0.1
0.2
0.3
0.5
0.6
0.7
0.8
0.85
1.05
1.1
1.2
1.5
1.8
2.3
3.2
4.0
Table 9.9-6
Factor
as a function of the draught-water depth ratio T/h
The berthing velocity shall be determined according to the site conditions and the following equation:
Equ. 9
Where:
berthing velocity (m/s)
standard berthing velocity (m/s) perpendicular to the jetty
The standard berthing velocity shall not be less than 0.3 m/s. For recreational vessels greater than 25
m in length, a berthing velocity of 0.2 m/s may be used and for floating ferry terminals a perpendicular
velocity greater than 0.3 m/s may be appropriate.
25
Coefficient
b1
Vessel with bow rudder
Vessel without bow rudder
Still water
Flowing water
Still water
Flowing water
0.6
0.5
1.0
0.8
Table 9.9-7
Coefficient
to be determined as follows
Unexposed
Coefficient
b2
Exposed
Favourable
approach
Unfavourable
approach
Favourable
approach
Unfavourable
approach
0.8
0.9
0.9
1.0
Table 9.9-8
Coefficient
to be determined as follows
Unexposed: protected against wind by a high bank, built-up surroundings or by trees and bushes.
Favourable approach: the vessel can be brought alongside without touching the berth.
If there are no explicit spring elements or structural springing available,
9.5.2
can be assumed.
Mooring Loads (Hawser Force)
Mooring loads are loads generally applied to structures by mooring lines or ropes. Such loads include
wind and current loads on moored vessels, transferred to the wharf, jetty or dolphin structures by the
mooring lines. Mooring loads may also include loads resulting from vessels manoeuvring to or from the
berth using engines and rudders while moored to bollards.
Forces acting on a moored vessel are produced by winds, currents, waves, tides and other water level
changes.
The determination of mooring loads involves an evaluation of many variables including the following:
Direction and magnitude of winds, currents and waves
Exposure of the berth and orientation of the vessel
Number and spacing of mooring points
Layout of mooring lines
Elasticity of mooring lines
Load condition of the vessel (light or loaded)
Wind and current pressures are very sensitive to small variations in velocity (varying as the square of
the velocity).
Their components of the moored ship are usually significant and should be calculated separately.
However, at marina piers and wharves where small boats are moored, surge and wake from passing
vessel shall be considered.
If no other information is available, the static mooring load (hawser force) can be determined according
to the following table:
26
Length (m)
Powerboats (kN)
Sailing Yachts (kN)
7
6.7
5.2
8
8.0
6.1
10
10.8
8.1
12
14.0
10.6
15
19.5
15.0
18
25.8
20.4
20
30.5
24.6
22
35.5
29.2
25
43.7
36.9
28
52.7
45.5
30
59.1
51.8
32
65.7
58.4
35
76.2
68.8
38
87.1
79.9
40
94.6
87.6
Table 9.9-9
Static mooring loads in relation to vessel length
The mooring load can be reduced by 25 % for floating pontoons secured by wire ropes or chains.
If there is no project specific information available, the directions of the mooring load can be assumed
to be between 10° and 45° to the longitudinal edge of the berth. The mooring load (hawser force) is to
be specified as the characteristic value for the anchoring elements (bollards, dolphins, foundations, etc.)
of the berth.
9.6
Other Loads
Each site and project is unique and should be evaluated accordingly. There might be a need to include
additional loads not mentioned in this document. Sound engineering judgment should be used
throughout.
9.7
Load Combinations
The marina elements and structures shall be designed to resist the above-mentioned loads (as
operational and ultimate loads) as well as loads during the various stages of construction.
The design calculation in the ultimate limit state as well as serviceability limit state shall be conducted
in compliance with regional valid national or international standards.
9.7.1
Durability
In addition to the structural integrity and serviceability, the marina elements and components should be
designed for durability of the materials for the intended design life.
The design life is defined as the period for which a structure or a structural element remains functional
for its intended purpose, with appropriate maintenance. It depends on the type of element, its function
and the
Type of facility
Design life (years)
Temporary works
5 or less
Small craft facility
25
Normal commercial structure
50
Table 9.9-10
Design life of structures
27
9.7.2
Floatability and Floating Stability
For floatability and floating stability calculations of floating structures as part of serviceability a factor of
safety of 1.0 shall be taken into account for the loads as described before. Stability requirements with
reference to metacentric height, freeboard and heeling angle are contained in chapter 10 of this report.
9.8
Reference List
In addition to related documents listed in chapter 1.2.4, the following documents are used as references.
Australian Standard AS 4997: Guidelines for design of maritime structures
British Standard BS 6349-1: Maritime Structures Part 1: General Criteria
British Standard BS 6349-4: Maritime Structures Part 4: Fendering & Mooring
British Standard BS 6349-6: Maritime Structures Part 6: Floating Structures
European Standard EN 14504: Floating Landing Stages
Marinas & Small Craft Harbour Regulations/Guidelines (Dubai)
Standards and Guidelines for Marina Development (Abu Dhabi)
UFC Design: Small Craft Berthing Facilities
28