Bjørnafjorden Suspension Bridge Design Basis rnafjorden Suspension Bridge Design Basis 0...

Bjørnafjorden Suspension Bridge Design Basis

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Design Basis

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30.05Lilleakerveien 4A 0283 OSLO Norway

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Bjørnafjorden Suspension Bridge 30.06.2016

Tittel / Title Utført/Prep.By Rev. av/Rev by Side/Page

Design Basis CH/HSL CH i

LIST OF REVISIONS

Rev Revised

A First Issue for comment. All sections regarding nature loads, analytical

methods etc. are taken directly from the Floating Bridge Group and should be

controlled carefully.

B Various revisions throughout the document

0 Issued for client

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Report 0 30.06.2016

Appendix A 0 30.06.2016

Appendix B 0 30.06.2016

Appendix C 0 30.06.2016


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Design Basis CH/HSL CH ii

TABLE OF CONTENTS

LIST OF REVISIONS ................................................................................................................................................. I

TABLE OF CONTENTS .......................................................................................................................................... II

1 INTRODUCTION ............................................................................................................................................. 1

2 INTRODUCTORY PROVISIONS .................................................................................................................. 2

2.1 AREA OF APPLICATION .................................................................................................................................... 2 2.2 DEFINITIONS ................................................................................................................................................... 2 2.3 PURPOSE ......................................................................................................................................................... 3 2.4 STRUCTURAL DESIGN ...................................................................................................................................... 3 2.5 DOCUMENTATION ........................................................................................................................................... 3 2.6 QUALITY ASSURANCE ..................................................................................................................................... 3

3 FUNDAMENTAL DESIGN PRINCIPLES .................................................................................................... 4

3.1 GENERAL ........................................................................................................................................................ 4 3.2 DESIGN METHOD ............................................................................................................................................. 4 3.3 SERVICE LIFE .................................................................................................................................................. 4 3.4 LONG-TERM DEVELOPMENT OF SEA LEVEL...................................................................................................... 4 3.5 STRUCTURAL RELIABILITY .............................................................................................................................. 4

4 FUNCTIONAL REQUIREMENT .................................................................................................................. 5

4.1 WATER TIGHTNESS .......................................................................................................................................... 5 4.2 DESIGN AND GEOMETRY ................................................................................................................................. 5

4.2.1 Road class ............................................................................................................................................. 5 4.2.2 Carriageway widths .............................................................................................................................. 5 4.2.3 Guard rail ............................................................................................................................................. 5 4.2.4 Protective Wind Screen ......................................................................................................................... 6 4.2.5 Structural weight contingency .............................................................................................................. 6 4.2.6 Water absorption .................................................................................................................................. 6 4.2.7 Maintenance ......................................................................................................................................... 6 4.2.8 Navigation channel ............................................................................................................................... 6 4.2.9 Safety systems for navigation ................................................................................................................ 6

5 MATERIALS .................................................................................................................................................... 7

5.1 CONCRETE STRUCTURES ................................................................................................................................. 7 5.1.1 General ................................................................................................................................................. 7 5.1.2 Material factors .................................................................................................................................... 7 5.1.3 Concrete ................................................................................................................................................ 7 5.1.4 Reinforcement quality ........................................................................................................................... 7 5.1.5 Normal reinforcement ........................................................................................................................... 7 5.1.6 Prestressing steel and systems .............................................................................................................. 7 5.1.7 Minimum thickness requirements ......................................................................................................... 7 5.1.8 Concrete cover ...................................................................................................................................... 7 5.1.9 Sacrificial anodes ................................................................................................................................. 8

5.2 STEEL STRUCTURES ......................................................................................................................................... 8 5.2.1 General ................................................................................................................................................. 8 5.2.2 Material factors .................................................................................................................................... 8 5.2.3 Construction steel ................................................................................................................................. 8 5.2.4 Main cables, hangers and top cables .................................................................................................... 9

6 LOADS ............................................................................................................................................................. 11


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Design Basis CH/HSL CH iii

6.1 GENERAL ...................................................................................................................................................... 11 6.2 PERMANENT ACTIONS ................................................................................................................................... 12

6.2.1 General ............................................................................................................................................... 12 6.2.2 Self-weight (G-W) ............................................................................................................................... 12 6.2.3 Equipment (surfacing, railings etc.) (G-Add) ..................................................................................... 13 6.2.4 Permanent water head (buoyancy) (G-B) ........................................................................................... 13 6.2.5 Permanent ballast (G-S) ..................................................................................................................... 13 6.2.6 Tether pretension (G-Tet) ................................................................................................................... 13 6.2.7 Shrinkage, creep and relaxation (G-D) .............................................................................................. 13 6.2.8 Prestressing forces (G-P) ................................................................................................................... 13

6.3 VARIABLE ACTIONS ...................................................................................................................................... 13 6.3.1 General ............................................................................................................................................... 13 6.3.2 Traffic loads (Q-Trf) ........................................................................................................................... 14 6.3.3 Temperature (Q-Temp) ....................................................................................................................... 14 6.3.4 General information on environmental loads ..................................................................................... 17 6.3.5 Hydrostatic and dynamic loads (Q-Wave and Q-Curr) ...................................................................... 17 6.3.6 Wind loads (Q-Wind) .......................................................................................................................... 18 6.3.7 Combination of nature loads (Q-E) .................................................................................................... 18 6.3.8 Marine Fouling (Q-M) ........................................................................................................................ 19 6.3.9 Variable unintended additional loads (Q-L) ....................................................................................... 19

6.4 ACCIDENTAL LOADS ..................................................................................................................................... 19 6.4.1 General ............................................................................................................................................... 19 6.4.2 Ship impacts ........................................................................................................................................ 20 6.4.3 Accidental filling of buoyancy elements.............................................................................................. 20 6.4.4 Extraordinary environmental loads .................................................................................................... 20

7 DESIGN LOADS............................................................................................................................................. 21

7.1 GENERAL ...................................................................................................................................................... 21 7.2 DETERMINATION OF LOAD ACTIONS .............................................................................................................. 21

7.2.1 General ............................................................................................................................................... 21 7.2.2 Non-linear effects ................................................................................................................................ 21 7.2.3 Hydrodynamic and wind dynamic response ....................................................................................... 21 7.2.4 Structural damping ............................................................................................................................. 22 7.2.5 Correlation – combined environmental effects ................................................................................... 22

7.3 LIMIT STATES ................................................................................................................................................ 25 7.3.1 General ............................................................................................................................................... 25 7.3.2 Ultimate limit state ............................................................................................................................. 25 7.3.3 Serviceability limit state - characteristic ............................................................................................ 26 7.3.4 Serviceability limit state – infrequent combination ............................................................................ 27 7.3.5 Accidental limit state (ALS) ................................................................................................................ 28 7.3.6 Fatigue limit state ............................................................................................................................... 29

8 TETHER DESIGN .......................................................................................................................................... 30

8.1 GENERAL ...................................................................................................................................................... 30 8.2 CONTROL OF LIMIT STATES .......................................................................................................................... 30 8.3 LOSS OR REPLACEMENT OF TETHER............................................................................................................... 31

9 DESIGN CRITERIA ...................................................................................................................................... 32

9.1 RESTRICTION OF MOVEMENTS ....................................................................................................................... 32 9.2 CONCRETE STRUCTURES ............................................................................................................................... 32

9.2.1 General ............................................................................................................................................... 32 9.2.2 Water tightness ................................................................................................................................... 32 9.2.3 Concrete joints .................................................................................................................................... 33 9.2.4 Crack widths ....................................................................................................................................... 33


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Design Basis CH/HSL CH iv

9.2.5 Transverse shear ................................................................................................................................. 33 9.3 STEEL STRUCTURES ....................................................................................................................................... 33

9.3.1 General ............................................................................................................................................... 33

10 EXPANSION JOINTS, BEARINGS AND EQUIPMENT .......................................................................... 34

10.1 BEARINGS ................................................................................................................................................ 34 10.1.1 General .......................................................................................................................................... 34 10.1.2 Design ............................................................................................................................................ 34

10.2 EXPANSION JOINTS ................................................................................................................................... 34 10.2.1 General .......................................................................................................................................... 34 10.2.2 Design ............................................................................................................................................ 34

10.3 EQUIPMENT .............................................................................................................................................. 35 10.3.1 Drainage and bilge system ............................................................................................................. 35 10.3.2 Hatches and ladders....................................................................................................................... 35 10.3.3 Surfacing ........................................................................................................................................ 35 10.3.4 Inspection and maintenance ........................................................................................................... 35 10.3.5 Instrumentation .............................................................................................................................. 35

11 REFERENCES ................................................................................................................................................ 36

A. WIND CLIMATE PARAMETERS FOR THE BJØRNAFJORDEN SUSPENSION BRIDGE ............... 1

A.1 WIND CLIMATE SUMMARY ......................................................................................................................... 2 A.2 WIND CLIMATE MODELS FOR THE SITE ....................................................................................................... 3 A.3 REFERENCES .............................................................................................................................................. 5

B. HYDROSTATIC AND HYDRODYNAMIC CLIMATE .............................................................................. 1

B.1 WAVE CONDITIONS .................................................................................................................................... 2 B.2 CURRENT .................................................................................................................................................... 5 B.3 TIDAL VARIATION ...................................................................................................................................... 7 B.4 TIDAL AMPLITUDES .................................................................................................................................... 7 B.5 WATER DENSITY ........................................................................................................................................ 8 B.6 TEMPERATURE ........................................................................................................................................... 9 B.7 MARINE FOULING ....................................................................................................................................... 9

C. OTHER ENVIRONMENTAL LOADS .......................................................................................................... 1

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Design Basis CH/HSL CH 1

1 INTRODUCTION

This document defines the basis of design and establishes the expected performance levels for the

crossing of Bjørnafjorden south of Bergen. The document covers the permanent bridge works.

Special design criteria for the temporary works shall be defined when the construction methods are

known. Where no special design criteria have been defined for the project, the design shall adhere to

the applicable Norwegian codes, standards and regulations.


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2 INTRODUCTORY PROVISIONS

2.1 Area of application

These design rules apply to the feasibility study for crossing Bjørnafjorden with a multispan

suspension bridge on floating foundations of the TLP type.

In case of conflicting rules, the specific rules will govern over general rules.

2.2 Definitions

Terms used in the design premises have the following meaning:

Floating bridge

- A floating structure, designed for traffic loads directly applied on to the floaters or on a

separately constructed carriageway, which may have fixed or floating supports between the

abutments.

TLP floater

- The TLP floater is a buoyant unit connected to a fixed foundation at sea bottom by

pretensioned tethers. The floating unit is rigidly connected to the suspension bridge tower to

ensure that the bridge structure and the floating foundation act as one structural unit.

Tether system

- Arrangement of tethers (tendons) consisting of a number of parallel vertical elements,

normally made of steel pipes, acting in tension. The tether system consists of all components

associated with the upper and lower connections, the steel pipes, and the bottom structures

designed to resist the tether forces.

Splash zone:

- External surface (between level -6.0 and level +6.0) that is periodically in contact with

seawater.

LAT

- Lowest astronomical tide

MSL

- Mean sea level. MSL is the reference water line used in the analyses.

HAT

- Highest astronomical tide

Service Life

- The service life of the structure estimated from its completion date.


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2.3 Purpose

The bridge structure and each separate element is to be designed such that the following criteria are

met during the required life of the structure:

- The bridge is fit for its purpose.

- Normal operation and maintenance is sufficient to keep the structure functional and

operational.

- Performs satisfactory under normal conditions.

- Secured watertight hull of the TLP.

- Capable of resisting all estimated loads and deformations with satisfactory resistance to

withstand failure or conditions similar to a failure.

- Has necessary safety to withstand a none intended event.

2.4 Structural design

Floating bridges, both at the detail level and globally, will be designed to achieve a structure that:

- Will be built in a safe and secure manner.

- Will behave in a ductile manner in the Ultimate Limit State and local damages will not

compromise the global integrity of the structure.

- A statically well-defined system with a simple stress development, where the calculation

model corresponds to the actual structure.

- Is robust against changes in structural properties, variations in material parameters, corrosion

and similar issues.

- Availability for inspections, maintenance and rehabilitation is satisfactory.

- Elements with shorter service life than the bridge service life are replaceable, eg. tethers,

cables, bearings, expansion joints etc.

2.5 Documentation

Documentation requirements are defined in Handbook N400 /1/.

2.6 Quality assurance

Requirements regarding quality assurance and internal control are defined in Handbook N400 /1/


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3 FUNDAMENTAL DESIGN PRINCIPLES

3.1 General

Floating bridges represent an area within engineering where experience is limited and the design will

show signs of a pilot project. This implies that all involved parties must continuously evaluate both

the design basis and results.

The design assumptions should be in accordance with specified tolerance requirements for the

construction and installation of the bridge structure.

The safety level that is set for this design basis is to be maintained regardless of technical concepts

or the lack of written regulations for the given concept.

All design shall be in accordance with relevant Eurocodes as well as publication N400 and other

rules and regulations by the Norwegian road administrations.

3.2 Design method

The design is based on the limit state method. The partial factor method according to Eurocode NS-

EN 1990 is the basis for the design process.

3.3 Service Life

Floating bridges are designed for 100 year service life (Design service life). The service life of 100

years should account for fatigue. Corrosion protection may have a shorter service life than 100

years, as long as replacement of the corrosion protection system and its parts is possible.

Components and equipment with service life shorter than 100 years should be replaceable. The

procedures of replacing such components should be described.

3.4 Long-term development of sea level

The structure is to be designed for the expected sea level increase up to 0.8 m within the service life

of the structure /9/.

3.5 Structural reliability

In general, the bridge is categorized as consequence class CC3 (High) and consequently reliability

class RC3 in accordance with NS-EN 1990 Annex B. Design Supervision Level DSL3 (extended

supervision, requiring independent third party checking) and Inspection Level IL3 (extended

inspection during execution, requiring third party inspection) shall be applied.


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4 FUNCTIONAL REQUIREMENT

4.1 Water tightness

Buoyancy elements (TLP hull and tethers) shall be water tight, see chapter 9.2.2 .

4.2 Design and Geometry

4.2.1 Road class

The road design should meet the requirements for design class H8 in N400/1/.

Design traffic volume: 12000-20000 AADT (2040)

Speed limit: 110 km/h

4.2.2 Carriageway widths

The road is to be constructed with 4 lanes 3.5 m wide each, with 1.5 m wide shoulders on both sides.

Carriageway width 2 x 10 m, with pedestrian/cycle lane of width 3.0 m. See Figure 4-1.

Figure 4-1 Carriageway widths

4.2.3 Guard rail

Strength class H2 with working width 1 m.


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4.2.4 Protective Wind Screen

The documentation in this project in the present phase (completion date July 1st-2016) is based on a

bridge without protective wind screen for the traffic.

4.2.5 Structural weight contingency

The ballast should be sufficient to include a 10 % weight contingency for all structural parts.

4.2.6 Water absorption

Water absorption of concrete panels with wetted surface is assumed to increase the weight by 1 %.

4.2.7 Maintenance

The structure should be designed such that easy access for inspection and maintenance is achieved.

Outer surfaces should have a slight decline to make sure there is good water runoff. Details should

be designed such that pockets of water do not occur.

4.2.8 Navigation channel

The vertical navigation clearance is defined as the clear distance from the water surface at level

HAT to the bridge deck soffit in free spans, and should not be less than:

- In navigation channel: 45 m

The requirement for vertical navigation clearance should include the deflection from traffic in the

serviceability limit state "rarely occurring”, chapter 7.3.3 , including effects of creep and shrinkage,

temperature, settlements and global change of water level.

Horizontal navigation clearance is defined as free width for ship passage, and should not be less

than:

- In navigation channel: 400 m

- Outside navigation channel: No requirements

4.2.9 Safety systems for navigation

The bridge shall be equipped with signs for ship and aeronautical navigation, ref. N400 /1/, 12.7.5.


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5 MATERIALS

5.1 Concrete structures

5.1.1 General

Handbook N400, /1/, and current standards apply, with the additions given in the clauses below.

5.1.2 Material factors

Material factors should be used in accordance to NS-EN 1992-1-1: 2004/NA:2008 Table NA.2.1N.

5.1.3 Concrete

The concrete, its aggregates and workmanship should be in accordance to the requirements in

Handbook R762 /3/, with necessary adjustments according to NS-EN-1992.

Minimum concrete grade shall be B45.

LWA concrete may be considered where advantageous.

5.1.4 Reinforcement quality

Rebar quality should be of B500NC according to NS 3576-3 and EN 10080.

5.1.5 Normal reinforcement

All cross sections shall have sufficient minimum reinforcement to ensure controlled cracking.

Centre distance between rebar in walls facing the sea is to be no greater than 200 mm.

Minimum rebar diameter is 16 mm for walls facing the sea and 12 mm otherwise.

All panels will have double sided reinforcement.

5.1.6 Prestressing steel and systems

Prestressing steel, its components and workmanship is to satisfy the requirements of EN 10138.

All prestressing ducts are to be grouted.

Prestressing cable anchorages shall be cast in with normal concrete cover requirements.

Cables planned to be replaced shall not be grouted. Approved measures for corrosion protection

shall be applied.

5.1.7 Minimum thickness requirements

Sufficient wall thicknesses should be used to achieve proper casting of the rebar with tolerances, /1/.

Construction joints and the junction between walls and the bottom slab is of specific design

importance to ensure a uniform and waterproof construction.

5.1.8 Concrete cover

Minimum cover to reinforcement according to /1/ is given in the Table 5-1.


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Table 5-1 Minimum concrete cover

Concrete cover

Exposure

class

Minimum cover

Submerged casted concrete XS2 120 mm1)

Areas in the splash zone external surface XS3 130 mm1), 3)

internal surface XS1 85 mm2), 3)

Submerged panels and bottom slab

(cast under dry conditions)

external surface XS2 85 mm2), 3)

internal surface XS1 85 mm2), 3)

1) Including 20 mm negative tolerance

2) Including 15 mm negative tolerance

3) The cover has been increased by 10 mm to allow for slip forming of concrete panels

5.1.9 Sacrificial anodes

Extra corrosion protection provided by sacrificial anodes placed on the outside of permanently

submerged concrete surfaces should be considered. The reinforcement net in the entire concrete hull

should be electrically connected to the anodes.

5.2 Steel structures

5.2.1 General

Handbook R762, Handbook N400 and current standards apply with the following additions in the

clauses below.

5.2.2 Material factors

Material factors should be used in accordance to relevant sections of NS-EN 1993.

For checks in the ultimate limit state see: NS-EN 1993-2: 2006/NA:2009 NA. 6.1.

Fatigue checks will be performed according to DNVGL-RP-C203 which is nearly identical to

requirements in NS-EN 1993-2: 2006/NA:2009 NA. 9.3 and NS-EN 1993-1-9: 2005/NA:2010

NA.3.

For cables and tension bars see: NS-EN 1993-1-11: 2006/NA:2009 NA.6.

5.2.3 Construction steel

Steel type and maximum thicknesses shall comply with the requirements in Norwegian Standards

NS-EN-1993-1 and NS-EN-1993-2.

Steel strength to be according to S355, alternatively S420 or S460.

5.2.3.1 Corrosion protection

All steel surfaces shall have sufficient corrosion protection.

The corrosion protection shall be designed for the structure's expected service life.


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Steel surfaces exposed to air shall be protected with coating according to Handbook R762, /3/,

unless specified otherwise.

Permanently submerged steel surfaces shall have cathodic protection in the form of either sacrificial

anodes or induced voltage.

All steel surfaces in tidal and splash zones shall be protected by special corrosion protection

systems, generally combined with a 30 mm rust allowance.

Enclosed surfaces unavailable for inspection and surface treatments, such as the inside of pipes, steel

hollow sections etc. shall be airtight and the airtightness ensured by pressure test.

Enclosed surfaces available for inspection and surface treatments, such as steel box girders, hollow

steel towers etc. shall be watertight. If internal corrosion protection is ensured by low internal

humidity, the structure shall be airtight. Doors, hatches and other openings shall be equipped with

gaskets and closing devices that ensure the airtightness. Valves (or something similar) must be

utilized to even out differences in pressure between the inside and outside of the airtight structure.

Railing fixes, embedded details and other minor steel parts shall in general be acid proof.

5.2.4 Main cables, hangers and top cables

Properties of the cable system shall in general fulfil the requirements in handbook N410, /5/.

The design of tension components shall comply with the requirements of

NS-EN-1993-1-11:2006+NA:2009

The design of this project is based on parallel strands for the main cable, locked coil cables for the

hangers and sheathed prestressing strands for the top cables. Properties of top cables with parallel

strands is detailed below.

As construction is more difficult than usual, there is a risk that the wires of the main cable are not so

uniformly stressed as for wires of a conventional suspension bridge. Main cable roll on pylon

saddles is likely to more pronounced than for conventional bridges. Unless more rigorous analyses

of these effects are made the nominal capacity of the main cables should be reduced by 5 %.

5.2.4.1 General requirements

Main cables and top cables shall be adjustable at the end and each strand of the top cable should be

replaceable.

Hanger rupture and loss of strength and stiffness of the cables due to a vehicle fuel spill fire is not

considered in the current phase of the project. Although, a fire protective coating for the main cable

at its lowest point is implemented. Risk of progressive collapse caused by hanger rupture is to be

considered.

Top cables shall be type Group C (NS-EN 1993-1-11: Table 1.1) comprising bundles of parallel

seven wire (prestressing) strands, anchored with wedges.

Table 5-2 lists the top cable material properties that shall be adopted (in accordance with EN 10138-

3: Strands):


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Table 5-2 Top cable properties

Parameter Property

Nominal Diameter 15.7mm

Nominal Area 150mm2

Tensile Strength 1860MPa

Minimum Breaking Load Pn 279kN

Elastic Modulus of single strand 195kN/mm2

Coefficient of thermal expansion αT = 12 × 10-6 per ºC

5.2.4.2 Corrosion protection

Both the main cables and the hangers shall be comprised of galvanized strands. In addition, the

hanger strands shall be greased with a spinner compound and finally contained within a HDPE outer

pipe. The HDPE outer pipe is assumed to be of the standard type with respect to diameter.

The individual strands of the top cables are sheeted strands protected by an external HDPE pipe.


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6 LOADS

6.1 General

The loads are divided into categories based on their nature and the likelihood of their occurrence:

- Permanent loads (G)

- Variable loads (Q)

- Accidental loads (A)

The classification of individual loads is shown below. Load designations are given with a symbol for

the main group as well as a symbol for type of load. Deformation loads are treated as permanent

loads in accordance to the Eurocodes.

Permanent loads (G)

- Self-weight G-W

- Permanent equipment (surfacing, railings etc.) G-Add

- Permanent water head (buoyancy) G-B

- Permanent ballast G-S

- Cable forces under permanent loads G-Cable

- Tether pretension G-Tet

Deformation loads (G)

- Shrinkage, creep, relaxation (deformation loads) G-D

- Prestress in tendons | G-P

- Forced deformations from erection G-Id

Variable loads (Q)

- Traffic loads Q-Trf

- Temperature Q-Temp

- Tidal loads Q-Tide

- Waves (hydrodynamic loads) Q-Wave

- Current Q-Cur

- Wind Q-Wind

- Marine fouling Q-M

- Additional unintended variable loads Q-L

Accidental loads (A)


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- Ship impact forces

- Anchor impacts and loads from falling objects

- Filling of floating body

- Loss of one tether

- Abnormal nature loads

- Hanger rupture

6.2 Permanent actions

6.2.1 General

Permanent effects are loads that are constant within the considered time frame, and include:

- Weight of the construction, surfacing and any non-removable equipment.

- Weight of permanent ballast

- External hydrostatic pressure from surrounding sea water up to the mean water level with mean

density (mean buoyancy)

- Pretension of tethers

For floating bridges an equilibrium group is made of these permanent loads, denoted G-EQ, which is

treated as one load group when combined with other loads.

Permanent loads linked to permanent deformations are also classified as permanent effects, such as:

- Prestressing of tendons.

- Shrinkage, creep and relaxation.

- Deformations applied to the construction as a result of erection or installation method.

For permanent loads the expected mean value is defined as the characteristic value. Buoyancy shall

be calculated based on the outer dimension of the construction without additions from fouling.

6.2.2 Self-weight (G-W)

The structures self-weight shall be calculated from the weight density of the relevant construction

material. The effect of potential water absorption shall be evaluated (assumed to be 1 %). The

greatest occurring weight density of the concrete including reinforcement is used. If the density turns

out to be lower, permanent ballast must be put in to account for this. Alternatively the draft will be

changed and the super structure must be corrected for this.

Weight of steel: 77 kN/m3

Normal weight concrete (reinforced): 26 kN/m3

Light weight concrete (reinforced): 22 kN/m3


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6.2.3 Equipment (surfacing, railings etc.) (G-Add)

Design road surface weight shall always be included in the self-weight

- 80 mm thick wearing surface on concrete: 2.0 kN/m2

- 80 mm thick wearing surface on steel: 2.0 kN/m²

- 60 mm thick wearing surface on steel for the walkway: 1.5 kN/m2

Weight of railings: 0.5 kN/m per railing

6.2.4 Permanent water head (buoyancy) (G-B)

The water density with variations is stated in Appendix 1B.5. The unfavorable value for the load

effect considered shall be used. Variation of the water's density is treated as a variable load, see

chapter 6.3.9.

6.2.5 Permanent ballast (G-S)

Permanent ballast may be solid ballast or water.

Rocks (aggregate): 20 kN/m3

Olivine: 24 kN/m3

Iron ore: 38 kN/m3

Water: 1025-1027 kg/m3 (see Appendix B.5)

6.2.6 Tether pretension (G-Tet)

Applies to the tether pretension that is included in the equilibrium group G-EQ.

6.2.7 Shrinkage, creep and relaxation (G-D)

Creep and shrinkage is applied in accordance with NS-EN 1992-1-1 2.3.2.2, 3.1.4 and 5.8.4

Relaxation is applied in accordance with NS-EN 1992-1-1 3.3.2 and 5.10.6.

6.2.8 Prestressing forces (G-P)

Applies to tendons in concrete structures. Effects of friction and anchor losses at tendon as well as

the time dependent effects shrinkage, creep and relaxation shall be taken into account when

determining the prestress forces in tendons.

Upper and lower values for the prestress force should be included in the calculations in situations

where there is uncertainty regarding the effective prestress, or in cases where the magnitude of the

prestress is of decisive importance for the structure's safety.

6.3 Variable actions

6.3.1 General

Variable operational loads are loads linked to the expected use of the structure, and include:

- Traffic loads


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Variable deformation loads are also regarded as variable actions, such as:

- Temperature

- Tides

Nature loads are usually regarded as variable actions, such as:

- Wind loads

- Wave loads

- Water current loads

Variable loads also include:

- Marine Fouling (Including weight)

- Additional unintended variable loads

Effects of ice and snow are omitted in the current phase of the project.

6.3.2 Traffic loads (Q-Trf)

The applied traffic loads are according to NS-EN 1991 and NA-rundskriv 07/2015.

6.3.3 Temperature (Q-Temp)

Design for thermal loading is carried out in accordance with NS-EN 1991-1-5:2003+NA:2008 and

NS-EN 1993-2:2006+NA:2009.

Uniform distributed temperature variation

The girder is defined as “Type 1” structure (steel bridge with box section) after NS-EN 1991-1-

5:2003+NA:2008.

The isotherm chart in the national annex defines the lowest and highest air temperatures with a 50-

year return period and is shown in Figure 6-1.

Figure 6-1 Air temperature, 50-year return period. Left: Maximum air temp. Right: Minimum air temp.


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For Bjørnafjorden, the following air-temperatures will be:

1. Tmax= 32 ℃.

2. Tmin= -22℃.

For type 1 structures, the national annex NA.6.1.3.1 defines the uniformly maximum and minimum

bridge temperatures as functions of max and min air temperature:

1. Te.max=Tmax+16℃= 48℃.

2. Te.min=Tmin-3℃= -25℃.

Assuming T0=11℃, which will be most favorable for the bridge during installation, the temperature

variation should be:

ΔTN.con/=T0-Te.min=11℃-(-25℃) = 36℃.

ΔTN.exp/=Te.max-T0=48℃-11℃=37℃.

ΔTk= +-37℃.

Bearings and expansions joints

NS-EN 1993-2: Bridges gives additional specifications for uncertainty of the temperature in Chapter

A.4.2.

ΔTd=ΔTk+ΔTγ+ΔT0

Where ΔTγ is a safety addition to account for uncertainty of the temperature difference in the bridge

and ΔT0 is a safety factor that accounts for the uncertainty of the bearings position at the reference

temperature. Since the uncertainly only is relevant for the expansion joint ΔT0=0.

ΔTk= 37℃.

ΔTγ= 5℃.

ΔTd=ΔTk+ΔTγ=37℃+5℃=±42℃.

Temperature gradient over girder height

Values from the vertical temperature differences are found in NS-EN 1993-2 Table NA.6.1 (shown

below). For type 1 bridges; ΔTm.heat=18℃ and ΔTm.cool=13℃.


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According to Note 2 in Table NA.6.1 the temperature difference shall be multiplied by a factor ksur

when the membrane thickness differs from 50 mm. The factor ksur is given in Table NA.6.2 (given

hereunder) for specific membrane thicknesses. Through linear interpolation 80 mm asphalt gives

ksur = 0.8 and ksur = 1.1.

The vertical linear variation temperatures are then:

Top side hotter than bottom side: ΔTm.heat = 18℃ x 0.8=14.4℃.

Bottom side hotter than top side: ΔTm.cool = 13℃x1.1=14.3℃.

Combinations factors for uniform and gradient temperature:

ΔTm.heat (or ΔTm.cool) + ωN ΔTN.exp (or ΔTN.con)

ωM ΔTm.heat (or ΔTm.cool) + ΔTN.exp (or ΔTN.con)

ωN=0.35

ωM=0.75


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Temperature loads for concrete floaters

For the partly submerged hulls, the relevant temperatures are given in

Table 6-1

Table 6-1 Temperatures gradients and differences for the concrete floaters

Temperature gradient across the thickness of external walls/slabs: A B

External faces (sea/air) 10 -10

Inner faces (inside of hull) 0 0

Temperature differences between structural parts of the hull: A B

Top slab 15 -15

Walls above MSL 10 -10

Walls/slabs below MSL 0 0

6.3.4 General information on environmental loads

The general basis in the Eurocodes is that the characteristic value of a variable environmental load

on a permanent structure is chosen as the least favorable load most likely to occur within a 50 year

return period. For structures where the environmental loads are dominant it has been found to be

more correct to define characteristic environmental loads for different return periods directly and to

use these loads into the combination for relevant return periods, rather than to decide Ψ-values.

Environmental loads include both wind, wave and sea current loads as well as the effect of sea level

changes. It has been decided to treat these loads as a characteristic load group (Environmental loads

Q-Ek) in combination with other loads.

6.3.5 Hydrostatic and dynamic loads (Q-Wave and Q-Curr)

Hydrostatic and hydrodynamic loading shall be determined based on recognized theory.

Information on hydrostatic and hydrodynamic climate is given Appendix B with suggestions for:

Description of the wave spectrum to be used

Description of directional spread

Description of the variation of the parameters mentioned above

Current parameters

The information in Appendix B is identical to that used for design of the Floating Bridge

Alternative.

Load effects from wind generated waves, swells and currents shall be determined. A double-peak

spectrum can also be used where this is considered appropriate. Analysis with waves will include

first order effects, effects of higher orders and sum-frequency effects.


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The analysis will also include loads from vortex shedding and varying current speeds with depth

shall be checked. Acceptable margins towards large transverse oscillations as a result of vortex

shedding shall be ensured where this is crucial to the structure's safety and functionality for current

speeds with a return period of 10 000 years.

A global dynamic analysis will be carried out to determine global dynamic load actions for

hydrodynamic loads. In the final phase of the project, such a dynamic analysis might be integrated

with the static analysis to produce reliable total loads. In the present phase of the project, the static

and dynamic analysis are performed with different calculation programs. Models used in these

programs will be verified individually as well as compared to each other in order to produce reliable

total loads. Such an analysis must be detailed enough to capture all the relevant natural periods of

the structure.

6.3.5.1 Slamming

Slamming should be analyzed according to the methodology given in DNV-RP-C205.

Horizontal slamming loads must be considered in relation to ship impact loads. If slamming loads

are assumed to be more severe than ship impact, a detailed slamming analysis shall be performed.

6.3.6 Wind loads (Q-Wind)

There are currently local wind and wave measurements going on in the Bjørnafjord. The local

measurements are conducted over a 5 year period and compared to (scaled to) a long history of

measurements done at a weather station nearby.

A basic description of the expected wind climate in the area has been developed in appendix A. The

description is based on the current codes, NS-EN 1991-1-4:2005, including national appendix

NA:2009, as well as supplementation from experiences obtained from similar projects carried out in

Norway.

Load effects from wind are divided into static load effects from mean wind values and dynamic load

effects from dynamic wind response. The total load action is taken as the sum of these load effects.

Calculation models in the frequency and/or time domain will be used for determination of wind

loading responses on these dynamic sensitive bridges. The challenges to this procedure given by this

special bridge structure are addressed in appendix A.

6.3.7 Combination of nature loads (Q-E)

Environmental loads are comprised of wind loads, wave loads and current loads as well as variation

of the sea level. These loads are treated as a characteristic loads group (Nature loads Q-Ek) in

combination with other loads. When establishing the characteristic load with relevant return period

the loads are combined as shown in the combination matrix in Table 6-2.

We suggest to include a combination with the same return period on wind waves and swell for all

return periods. The rationale behind this is that swell is a result of a storm generating a near shore

harsh condition that is transferred to the bridge location through refraction and defraction. This

means that the local wind generated sea will be a result of the same storm hence the return period

should be equal. The current is more a result of tidal variation and it would probably not be correct

to combine the same return period on current as for the waves and wind as there is no clear statistical

correlation. The same argument goes for the sea level also where mean sea level has been selected.


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Table 6-2 Combination of return periods for environmental loads

Return

period

Wind Waves Current Sea level

Wind generated Swells

1 1 1 1 1 Mean

10

10 10 1 10 10

1 1 10 1 Mean

10 10 10 10 Mean

100 100 100 10 100 100

10 10 100 10 10

100 100 100 100 Mean

10000 10000 10000 100 10000 Mean*)

100 100 10000 100 Mean*)

10000 10000 10000 100 Mean*)

*) Storm tides should be included

6.3.8 Marine Fouling (Q-M)

Marine Fouling is assumed to occur on structural surfaces against the sea and up to 0.5 m above the

still water level.

Dist. from water level Thickness Mass per m2 Submerged weight per m2

+0.5 to -12 m 150 mm 200 kg/m2 468 N/m2

below level -12 m 75 mm 100 kg/m2 234 N/m2

6.3.9 Variable unintended additional loads (Q-L)

The TLP-unit may be subjected to unintended additional load. This may be caused by change in

weight density of the concrete because of water absorption, variation of the water density, or

because of imprecise re-ballasting. Other variations in static loads could be:

- Rehabilitation and increased weight of asphalt

- Tolerances on weight of permanent equipment in the floaters.

Such variations can be corrected by regulation of the permanent ballast.

6.4 Accidental loads

6.4.1 General

Accidental loads are loads imposed to the structure due to incorrect operation or extraordinary

situations, such as:

- Ship collisions

- Unintended filling of buoyancy bodies


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- Failure of a single tether

- Extraordinary environmental loads

- Rupture of hangers

- Submarine landslides

Representative values for accidental loads are generally nominal values determined from

engineering judgement and cannot be linked to a specified probability level. The probability of

incidents that can be disregarded in the analysis should not be greater than 10-4 per year, to the

extent the accidental load can be determined based on probability calculations.

6.4.2 Ship impacts

Ship impacts are to be assessed based on the risk analysis report /14/, in which a 50 MJ impact to the

floater hull is estimated as having a 10-4 annual probability of return. Both the local and the global

response to a collision event should be evaluated. Further, the consequence of impact from vessels

that frequently transit the crossing but is outside of the estimated 10-4 level should be investigated to

verify the robustness of the bridge design.

For assessment of the local collision response, focus is to be placed on assessing the local damage

extent to verify that the damage is within the damage stability requirements of maximum two-

compartment damage in the collision prone area, and assess the reparability of the resulting damage.

Both shear and bending capacity of the floater hull, as well as punching shear capacity is to be

assessed based on simplified methods or full NLFEA simulations of the impact.

For assessment of the global response, the effect of the transfer of momentum from the ship to the

bridge and the following global deflection of the bridge should be evaluated. Force-displacement

curves of a relevant striking ship can be used to create a realistic loading. A perpendicular impact is

assumed to obtain a conservative response estimate. Both the short-term damage during the actual

impact and the following dynamic deflection of the bridge is to be considered. Key parameters are to

be assessed, such as maximum deflection of the bridge, the possibility of compressive tether forces

and the motion response of the bridge girder.

6.4.3 Accidental filling of buoyancy elements

Unintended filling of buoyancy bodies includes filling of one or two neighboring chambers close to

the sea.

- Above elevation -10.0: Filling of two neighboring chambers.

- Below elevation -10.0: Filling of one chamber.

All compartments shall be fitted with permanent water detectors.

6.4.4 Extraordinary environmental loads

Neglected during this phase of the project.


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7 DESIGN LOADS

7.1 General

The structure shall be checked for the following limit states:

- Ultimate limit state (ULS)

- Serviceability limit state (SLS)

- Accident limit state (ALS)

- Fatigue limit state (FLS)

Design load effects in the different limit states are determined by combining the effects of

characteristic loads multiplied by the load coefficients detailed in the following paragraphs.

Geometric deviations should be included in the calculations with their most unfavorable tolerance

limits in situations where it can have especially unfavorable effects on the structure's safety.

Alternatives to the partial factor method can be considered in relation to checks of stability, design

of anchorages, as well as in determining bridge movements where dynamic effects are relevant.

The reference water line for intended tether tension is MSL (level ±0.0).

7.2 Determination of load actions

7.2.1 General

Load actions shall be determined by using recognized methods that take into account the variation of

loads in time and space, the response of the structure, the relevant environmental and soil conditions,

as well as the limit state that is being controlled. Simplified methods can be used if it is sufficiently

documented that they provide safe results.

7.2.2 Non-linear effects

Non-linear effects shall be evaluated, e.g. by using linearized models which give results on the safe

side, when it can be of relevance due to load and response characteristics. If such a simplification is

impossible then a non-linear analysis shall be used.

7.2.3 Hydrodynamic and wind dynamic response

Load effects of wind, waves and current are calculated separately. For combined effects see

procedure outlined in Section 7.2.5 .

Hydrodynamic response is calculated using methods that give a good description of the actual water

kinematics, the hydrodynamic coefficients and the interaction between fluid and structure.

Calculation procedure should include possible non-linearity in the load definition, including any

non-linear behavior of moorings; if used.

Characteristic values of wave loading are found by:

Simulation of 10 no. of 3 hrs. storm conditions for each of the dimensioning sea states


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Simultaneous simulations of wind generated waves and swell generated waves

Extreme values taken as mean of the 10 maxima found in the simulations

Characteristic values taken as mean extreme multiplied by 1.25; approximating the 95%

percentile in the extreme value distribution

Bases for the hydrostatic and hydrodynamic loading are given in Appendix B “Hydrostatic and

hydrodynamic climate”.

Wind loading is determined based on the procedures described in NS-EN 1991-1-4. The procedure

should be based on the following characteristics:

Wind as a Gaussian process

Structure linear elastic

Response also a Gaussian process

Maximum thus Rice distributed

Extreme values Gumbel distributed

Characteristic values for wind loading are taken as expected maximum for the Gumbel distribution,

and are found by:

- Calculation from the standard deviation of the response and the corresponding peak factor.

- Peak factor dependent upon duration (T) and zero-crossing frequency nv

- Calculations will be based on 10 min duration period

Bases for the wind loading are given in Appendix A “Wind climate parameters for the Bjørnafjorden

”.

7.2.4 Structural damping

The following values can be used for structural damping:

- steel: C = 0.005

- concrete, uncracked: C = 0.008

- concrete, cracked: C = 0.016

where C = / 2

= logarithmic decrement.

For the global analyses the structural damping should be based on C = 0.5 % of critical.

7.2.5 Correlation – combined environmental effects

Load effects of wind, waves and current are calculated separately. The combined effects are thus

given by the algebraic composition:

Q-Env = Q-Wind + Q-Wave + Q-Curr

The wind part consists of a static and a dynamic term:


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Q-wind = Q-Wind_stat + Q-Wind_dyn

For the present location, current is of marginal importance and is thus handled as a static loading

term. The combined environmental effects can therefore be given as:

Q-Env = Q-Env_stat + Q-Env_dyn

where:

Q-Env_stat = Q-Wind_stat + Q-Curr

Q-Env_dyn = Q-Wind_dyn + Q-Wave

The procedure given in the separate sections for wind and wave describe the calculation of

characteristic values for each of these load effects. The remaining challenge is thus to find an

appropriate rule for the combination of these extreme values for the dynamic part of the

environmental loading. The pure static part will always be present with full values.

As the extreme dynamic values are found for different stochastic processes with different frequency

content and different response behavior, it is unlikely that extreme values will occur simultaneously

for all processes. Since different responses for the same processes (e.g. bending moment about the

two axes) also are found as expected extreme values, the probability that these occur at the same

time also has to be determined.

This task requires an additional response characteristic to be determined, the correlation between the

different processes and responses. If the correlation is complete (i.e. the correlation is ±1) the

maximum values occur at the same time and the appropriate combination is a summation of extreme

values. If the processes are uncorrelated (i.e. the correlation is 0) the combined extreme value may

be found by the “square-root-sum-of-squares”-rule.

In handbook N400, 2011 chapter 4.3.1.2.4 a method of combining extreme values from dynamic

loading (correlation) is described. The method applies a combination factor α to be used on the

coinciding maximum sectional forces. For fully correlated forces α = 1.0 is given. For uncorrelated

forces the simplified method recommends a factor of 0.5 for the coincidental forces. The handbook

also describes a more detailed method to determine the factor, which for uncorrelated forces is based

on sums of square values:

𝛼𝑗 =√∑ 𝜎𝑗

2 − 𝜎𝑗

∑ 𝜎𝑗 − 𝜎𝑗

Where, j = 1 to 6 represents the six force components in the section and σj is the stress results from

each of these force components.

Dependent on number of force components with significant stresses the α -factor can vary.

Regarding the bridge girder, the significant stresses mainly come from force components such as

moment about strong, moment about weak axis and torsion. If we consider two force components

giving equal stresses we get a factor of

α = ((12+12)0.5-1)/1 = 0.41

For three force components giving equal stresses we get:


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α = ((1^2+12+12)0.5-1)/2 = 0.37

For two force components with one giving 75 % stress and the other 100 % stress

α = ((1^2+0.752)0.5-0.75)/1.0 = 0.5

For two force components with one giving 50 % stress and the other 100 % stress

α = ((1^2+0.52)0.5-0.5)/1.0 = 0.62

It is seen that for non-correlated force components the combination factor increases when the

relative magnitude of the stress of the coincidental force decreases. For three force components with

significant stresses the factors will be a little lower.

In this project, the design checks are performed with method one and verified by method two.

1. Maximum characteristic force components from dynamic wave and wind loading are

determined from analyses. Force components from wave loading are combined assuming no

correlation between them, using a combination factor of 0.4 for the coincidental force

component. Characteristic dynamic wind is added using a combination factor of 0.6 on

dominating force component. For other force components for dynamic wind, 0.4 is used. Static

wind response is considered to be fully correlated with wave and dynamic wind and a

combination factor of 1.0 is used. See also combination matrix in Table 7-1.

2. The second method is to extract stresses at selected points in bridge girder directly from the

time domain dynamic wave analysis in OrcaFlex and compare it with the stresses extracted by

the first method. If the stresses in the last method are higher the combination factors should be

increased accordingly.

Table 7-1 ULS combination table


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7.3 Limit states

7.3.1 General

The following has been taken into account when establishing the load coefficients:

- The possibility for loads to deviate from the characteristic values.

- The reduced probability for different loads contributing to the total evaluated load effect to

achieve their characteristic values simultaneously.

- Deviations in the load effect calculation, to the extent that such deviations can be assumed to

be independent of the construction material and design tolerance.

7.3.2 Ultimate limit state

The ultimate limit state shall be established for load combinations according to NS-EN

1990:2002/A1:2005/NA:2010 Table NA.A2.4 (B), equation 6.10a and 6.10b.

The load descriptions are defined in section 6.1

An equilibrium group for characteristic permanent loads G-EQk containing self weights, buoyancy,

fixed ballast, tether pretension is established.

Wind, wave and current loads are treated as a characteristic load group (Nature loads Q-Ek) in

combination with other loads. For internal combination of nature loads see section 6.3.7 and 7.2.5

Characteristic load for environmental loads on bridge without traffic loading is chosen to a return

period of 100 years.

Characteristic load for environmental loads on bridge with traffic load is calculated as the largest of

three loading scenarios; wind with a return period of 1 year, 50% of loading with a 100 year return

period, or an environmental load with a return period which corresponds to wind gusts of 35 m/s at

bridge deck elevation (this applies to bridges without wind screens).

Table 7-2 shows the principles for combining loads at the ultimate limit. Not all possible

combinations are shown and other possible combinations must be evaluated by the designer for the

individual projects. E.g. the case of dominant permanent load combined with 100 year nature load

without traffic has not been included.

γ is load factor in accordance to NS-EN 1990:2002/A1:2005/NA:2010 Table NA.A2.4(B).

Ψ0 is combination factor in accordance to NS-EN 1990:2002/A1:2005/NA:2010 Table NA.A2.1.

For bridge without traffic loads the environmental loads are only evaluated as dominant loads (can

also evaluate permanent loads, temperature and other loads as dominant).


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Table 7-2 Load combination in ULS (comb B)

1) For permanent loads high or low factors are used. For certain checks a low factor of 0.9 shall be used instead of

1.0. This is evaluated separately.

2) For bridges with span length >500 m the factor 1.35 shall be replaced with 1.2, ref. NA400.13.2.1

7.3.3 Serviceability limit state - characteristic

The characteristic serviceability limit state shall be established for load combination in accordance

to NS-EN 1990:2002/A1:2005/NA:2010 Table NA.A2.6.

Load combinations in the characteristic serviceability limit state shall be used to determine bearing

displacements, etc.

The load definitions are defined in section 6.1 .


fixed ballast and pretension of tethers is established.

Wind, wave and current loads are treated as a characteristic load group (Environmental loads Q-Ek)

in combination with other loads. For internal combination of environmental loads see section 6.3.7 .

Characteristic load for environmental loads on bridge without traffic loads is determined for a return

period of 100 years.

Characteristic load for environmental loads on bridge with traffic load is calculated as the largest of

three loading scenarios; wind with a return period of 1 year, 50% of loading with a 100 year return

period, or an environmental load with a return period which corresponds to wind gusts of 35 m/s at

bridge deck elevation (this applies to bridges without wind screens).

Table 7-3 shows the principles for combining loads at the characteristic serviceability limit. Not all

possible combinations are shown and other possible combinations must be evaluated by the designer

for the individual projects.

Ψ0 is combination factor in accordance to NS-EN 1990:2002/A1:2005/NA:2010 Table NA.A2.1.

Dominant loads G- EQK Q-TrfK Q-TempK Q-EK(1y) Q-EK(100y) QK

m/traffic u/traffic

γ x Ψ0 γ x Ψ0 γ x Ψ0 γ x Ψ0 γ x Ψ0 γ x Ψ0

Permanent load

Permanent load 1) G- EQK 1.352)/1.0 1.2/1.0 1.2/1.0 1.2/1.0 1.2/1.0 1.2/1.0

Variable loads

Traffic loads Q-TrfK 0.95 1.35 0.95 0.95 - 0.95

Temperature loads Q-TempK 0.84 0.84 1.2 0.84 0.84 0.84

Environmental loads with traffic Q-EK(1y) 1.12 1.12 1.12 1.6 - 1.12 Environmental loads without traffic Q-EK(100y) - - - - 1.6 - Other loads QK 1.05 1.05 1.05 1.05 1.05 1.5


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For bridge without traffic loading the environmental loads are only estimated as dominant loads (can

also evaluate permanent loads, temperature and other loads as dominant).

Table 7-3 Load combination in SLS Characteristic

7.3.4 Serviceability limit state – infrequent combination

The in-frequent combination in serviceability limit state shall be in accordance to NS-EN

1990:2002/A1:2005/NA:2010 Table NA.A2.6.

Load combinations in in-frequent serviceability limit state with 1 year return periods shall be used to

check deflections, displacements and accelerations.

The quasi-permanent or frequently occurring load combinations are the basis for controlling

cracking and compression zone height in accordance to Eurocode NS-EN 1992-1-1 (ref table

NA.7.1N). However, these load combinations do not include the contributions from traffic,

environmental loads and temperature simultaneously. For negligible environmental loads the rarely

occurring and frequent occurring combinations give approximately the same load effect. For high

environmental loads the two combinations give very different results. It is therefore reasonable to

use the rarely occurring combination for control of the compression zone height and cracking where

environmental loads and traffic loads can occur simultaneously.

The load factor for dominant temperature load is 1.0 when checking compression zone height.

The load notations are defined in section 6.1 .


fixed ballast, stay cable pretension and mooring pretension is established.

Dominant loads G-EQK Q-TrfK Q-TempK Q-EK(1y) Q-EK(100y) QK

w/traffic w/traffic

Ψ0 Ψ0 Ψ0 Ψ0 Ψ0 Ψ0

Permanent loads

Permanent loads G-EQK 1.0 1.0 1.0 1.0 1.0 1.0

Variable loads

Traffic loads Q-TrfK 0.7 1.0 0.7 0.7 - 0.7

Temperature loads Q-TempK 0.7 0.7 1.0 0.7 0.7 0.7 Environmental loads with traffic Q-EK(1år) 0.7 0.7 0.7 1.0 - 0.7 Environmental loads without traffic Q-EK(100år) - - - - 1.0 -

Other loads QK 0.7 0.7 0.7 0.7 0.7 1.0


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Table 7-4 shows the principles for combining loads at the rarely occurring serviceability limit. Not

all possible combinations are necessarily shown and other possible combinations must be evaluated

by the designer for the individual projects.

Characteristic load for environmental loads for the in-frequent combination is calculated with a 1

year return period, i.e. Ψ1, infq x Ek(50 year) is replaced with 1.0 x Ek (1 year).

Ψ1 / Ψ1,infq are combination factors in accordance to NS-EN 1990:2002/A1:2005/NA:2010 Table

NA.A2.1.

Table 7-4 Load combination in SLS Rarely Occurring

Dominant loads Q-TrfK Q-TempK Q-EK(1year) QK

Ψ1 / Ψ1,infq Ψ1 / Ψ1,infq Ψ1 / Ψ1,infq Ψ1 / Ψ1,infq

Permanent loads

Permanent loads G-EQK 1.0 1.0 1.0 1.0

Variable loads

Traffic loads Q-TrfK 0.8 0.7 0.7 0.7

Temperature loads Q-TempK 0.6 0.8 0.6 0.6

Nature loads Q-EK(1year) 0.75**) 0.75**) 1.0*) 0.75**)

Other loads QK 0.6 0.6 0.6 0.8 *)1.0 replaces 0.8 x 50 years in table A2.1, which is assumed to equal 1 year.

**) 0.75 = 0.6/0.8. Scaled from 50 years to 1 year.

7.3.5 Accidental limit state (ALS)

The accident limit state shall be checked in two stages, a and b, with load factors as given in Table

7-5.

a: The structure in a permanent situation is subjected to an accident load. The purpose is to control

the magnitude of local damage for such an action.

b: The structure in damaged condition. A damaged condition can be local damage as stated in a, or

any other more explicitly defined local damage.

Design values for loads in the accident state are in accordance to

NS-EN 1990:2002/A1:2005/NA:2010 Table NA.A2.5. Ψ2 is a combination factor in accordance to

NS-EN 1990:2002/A1:2005/NA:2010 Table NA.A2.1.


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The load definitions are defined in section 6.1 .


fixed ballast, stay cable pretension and mooring pretension is established.



Characteristic load for abnormal environmental loads are calculated with a 10 000 year return

period.

Characteristic load for environmental loads for a damaged structure is calculated with a 100 year

return period.

Possible transient effects must be evaluated.

Table 7-5 Load combinations in ALS

*)10000 years

7.3.6 Fatigue limit state

A simple evaluation is carried out during this phase.

At a later stage a thorough design check should be performed.

Stage a Stage b (damaged condition)

Abnormal

nature loads

Ship

impact

Chamber(s)

filled with

water

Lost

tether

Other

damage

Ψ2 Ψ2 Ψ2 Ψ2 Ψ2

Permanent loads

Permanent loads G- EQK 1.0 1.0 1.0 1.0 1.0

Variable loads

Traffic loads Q_TrfK 0.2 0.2 0.2 0.2 0.2

Temperature loads Q-TempK 0 0 0 0 0

Other loads QK 0 0 0 0 0

Environmental loads in

event of damage Q-EK(100 year) 0 0 1.0 1.0 1.0

Accident loads

Abnormal nature loads Q-EK(*) 1.0

Ship impact A 1.0

Chamber(s) filled with water A 1.0

Lost tether A 1.0

Other damage A 1.0


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8 TETHER DESIGN

8.1 General

A final tuning of tether tension shall be performed for the completed bridge just before bridge

opening. Proper instrumentation for such tuning is required in N400, /1/, paragraph 13.12.7.

By adjusting the amount of permanent ballast in the TLP hull the pretension of the tethers can be

tuned to theoretical values with good accuracy. Thus an important reference basis has been

established.

Paragraph 13.12.7, /1/, also requires monitoring of tether forces and possibility for adjustments

during the service life of the bridge. The roomy requirement to minimum amount of permanent

ballast (10 % of the weight of all structural parts, paragraph 4.2.5) will ensure that tuning of tether

can be made at any time.

8.2 Control of Limit States

The measurements required in 8.1 is in fact a control of an equilibrium group of permanent loads

where the measured pretension, P0, is the difference between the buoyancy, B1, and the total

vertical self-weight, G1. According to N400, (B1-G1) = P0, can be considered as a common

permanent load with the same load factor in the various limit states. Thus, the limit state control of

tethers could simply be performed by using the load factors for “G-EQk” on the theoretical

pretension P0, ref. 7.3.2 - 7.3.6 .

Slack is not allowed in ordinary limit states.

Control of slack ULS(A):

Load factor 0.9 on pretension, 1.0 on other permanent loads.

Based on control and tuning of tether pretension during operation, ref. 8.1 , weight of marine fouling

and water absorption can be taken equal to 50 % of the values given in 6.3.8 and 4.2.6

Slack is not allowed in ordinary limit states.

Control of max tether force ULS(B):

Load factor 1.2 on pretension, 1.0 on other permanent loads.

Load factors on other loads: To be taken from table in 7.3.2

Note: According to N400 variations in buoyancy (±1 %) should be classified as an “Other load”.


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8.3 Loss or replacement of tether

Loss of a single tether or planned replacement of a tether shall be for controlled for load

combinations according to 7.3.5 . Effects of a sudden rupture should be considered.

If traffic is allowed during the replacement period, the TLP structure shall satisfy the ULS and SLS

criteria for the combined effect of traffic and environmental loads with a return period of 1 year.


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9 DESIGN CRITERIA

The assumptions and limit state values in the following are taken from relevant codes and projects’

design basis. Where relevant codes or other design basis documents are not found, experience data is

extracted from similar types of projects.

9.1 Restriction of movements

The Eurocodes and N400 /1/ do not specifically give requirements for movements of floating

bridges. Movements addressed here are deflections, rotations and accelerations. In lack of formal

criteria, the project design group has developed a set of limitations for control of movements. The

aim is to ensure adequate safety and control for the users.

Table 9-1 is based on information from previous studies on floating bridges, motion criteria for

pedestrian bridges and relevant requirements in N400 for conventional bridges. Below the table are

some comments to the various criteria.

Table 9-1 Motion criteria

Motion Load Criterion

Angular deviation, α, of bridge deck at support 0.7 x traffic tan α ˂ 1/30

Rotation of bridge girder (roll) due to traffic 0.7 x traffic 1 deg

Rotation of bridge girder (roll) du to static wind 1 year storm 0.5 deg

Rotation of bridge girder (roll) due to env. loads 1 year storm 1.5 deg (rms)

Vertical accelerations 1 year storm 0.5 m/s2 (rms)

Horizontal accelerations 1 year storm 0.3 m/s2 (rms)

- The acceleration criteria are based on recommendations from ISO 2631/1 and 2631/3- 1985.

The horizontal accelerations has been reduced by 0.1 m/s2 to take account of possible

reduced tire friction at vehicle speed 110 km/hour.

9.2 Concrete structures

9.2.1 General

Concrete structures shall be designed in accordance to NS-EN-1992.

9.2.2 Water tightness

The submerged boundaries of the hulls shall be water tight. This is ensured using criteria given in

NS 3473:2003 Table A.9 column B “Særlige strenge krav til tetthet”.

All structural parts subject to one-sided water pressure shall be checked for pressure forces from

both sides to ensure a tight stricture.


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There shall be no tensile stresses in concrete panels along the wetted perimeter of the hulls. This

applies for membrane forces for in-frequent (rarely occurring) load combination in SLS.

In addition the following applies for panels along the wetted perimeter: The minimum compression

zone depth across the concrete panel thickness for hulls shall for the same load combination be no

less than 100 mm. For prestressed concrete panels, the ducts must lie 100 mm within the

compression zone for the same SLS combination.

There are no special tightness requirements for the ultimate limit state. However, the reinforcement

strain should be limited to a yield strain of 0.2 %. This should also apply to accidental load cases.

9.2.3 Concrete joints

Joints subject to permanent water pressure or wave slamming shall have double seals.

9.2.4 Crack widths

The crack widths shall not exceed the values given in /1/ for load actions calculated in SLS – Rarely

occurring combination. Water pressure in cracks should be accounted for where relevant.

9.2.5 Transverse shear

Water pressure in cracks shall be accounted for when performing shear capacity checks of slabs

subject to water pressure.

Walls subject to water pressure should be considered for minimum shear reinforcement.

Shear reinforcement strain is limited to 0.9 x yield strain.

9.3 Steel structures

9.3.1 General

Steel structures shall be designed in accordance with NS-EN-1993.

The design as a whole shall as far as possible be based on the selected codes. Combining several

codes and recommended practices for the same structure should be avoided.


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10 EXPANSION JOINTS, BEARINGS AND EQUIPMENT

10.1 Bearings

10.1.1 General

The bearings shall be suitable for the types of loads, motions and environments the structure will be

subject to. The parts of the bearing structure with an expected service life less than a 100 years

should be replaceable.

10.1.2 Design

Maximum forces are determined in the ultimate and serviceability limit states. Calculated values

shall not exceed the capacity guaranteed by the supplier.

The following effects shall be accounted for when checking bearing movements:

- Temperature

- Creep, shrinkage, prestressing and other potential loads

- Ambient temperature at installation of the bearing.

- Deformations (including elastic deformations) and movements due to construction method,

foundation settlements and other variables.

Maximum deflections shall be calculated in the characteristic serviceability limit state.

Design bearing displacements shall not exceed the upper deformations values given by the supplier.

It shall be ensured that the joint/bearing structure's displacement and rotational capacity is adequate

for the applied calculation model for checking of ultimate limit state.

10.2 Expansion joints

10.2.1 General

The expansion joints shall allow snow ploughing, and should be dampened to avoid unnecessary

noise.

Expansion joints should not be placed at the bottom of sag-curves.

Extra water runoff systems should be included beneath the expansion joints, to make sure that water

does not run down on underlying structures.

Expansion joints shall be easily accessible. The expansion joint's wearing parts shall be possible to

disassemble for one driving lane at a time. Fasteners shall be resistant in contact with sea water and

easy to detach when being replaced.

10.2.2 Design

Expansion joint displacement and rotation shall not exceed the upper deformations values given by

the supplier.


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In the characteristic SLS the distance between joint edges or slats that can be in contact with the

wheels shall not exceed 80 mm.

10.3 Equipment

10.3.1 Drainage and bilge system

The study is based on using pumping system to be installed in all compartments of the buoyancy

elements, unless these are open to the sea, or filled with floating bodies that prevent water filling.

10.3.2 Hatches and ladders

Hatches, ladders, stairs and landings to provide clear access to closed compartments in the floating

bridge structure shall be included. Buoyancy elements shall have manholes with water tight hatches.

Walkways between rooms shall as far as possible lie above the water level.

10.3.3 Surfacing

The bridge structure and onboarding ramps shall have cover (wearing surfaces). The wearing

surfaces shall be designed as:

- Bituminous wearing layer on concrete or steel base courses, depending on the type of

structure.

A 80 mm thick wearing surface will be taken into account in this phase of the design.

10.3.4 Inspection and maintenance

Access to all structural elements and equipment that requires regular inspection and maintenance

during the service life of the bridge structure shall be included.

10.3.5 Instrumentation

Detail design of instrumentation for continuous measurements of the structure's motions and other

load responses as well as monitoring of potential protection systems, reinforcement corrosion or

other deterioration, is assumed to be determined at a later phase.

Design and operation principles as well as scope will described during a later phase in the project.

This also applies to installation of instruments and alarm devices for registration of unexpected large

accumulations of water in buoyancy elements.


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11 REFERENCES

A: Rules and regulations from NPRA:

/1/ Statens vegvesen: Håndbok N400, Bruprosjektering (2015)

/2/ Statens vegvesen: Håndbok N100: Veg- og gateutforming (2013).

/3/ Statens vegvesen: Håndbok R762: Prosesskode 2- Standard beskrivelse for bruer og

kaier (2012)

/4/ Statens vegvesen: Håndbok N101: Rekkverk og vegens sideområder

/5/ Statens vegvesen: Håndbok N410: Kabler til hengebruer

B: Norwegian Standards:

Norwegian Standard NS-EN 199X, X being a figure from 0 to 9.

Referred to directly in the text

C: Reports and publications

/6/ Bridge across Bjørnafjorden Metocean conditions, SINTEF, 2013-05-08

/7/ SSPA: Fergefri E 39 – Ship collision risk analysis for the Bjørnafjorden crossing

(several preliminary versions, last 2015.02.20)

/8/ Multiconsult: Bjørnafjorden – Bunn og grunnundersøkelser (2012.06.25)

/9/ IPCC, «Fifth Assessment Report» (2009).

D: Other rules and regulations/Basic documents :

/10/ PETROLEUMSTILSYNET, Forskrift om utforming og utrustning av innretninger med

mer i petroleumsvirksomheten (Innrettingsforskriften ), April 2010

/11/ PETROLEUMSTILSYNET, Veiledning til Innretningsforskriften, April 2010

/12/ NORSOK standard N-001, Rev. 7, Juni 2010

/13/ PETROLEUMSTILSYNET, Veiledning til Innretningsforskriften, April 2010

/14/ RE20146979-03-00-A Risk assessment for the planned crossing of Bjørnafjorden 150615


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Design Basis CH/HSL CH A.1

A. WIND CLIMATE PARAMETERS FOR THE

BJØRNAFJORDEN SUSPENSION BRIDGE


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A.1 Wind climate summary

Statens Vegvesen has specified that all concepts on the Bjørnafjorden should use the same wind

climate. The parameters herein are derived from the Metocean report for the Bjørnafjorden /1/.

For parameters that are not given in the Metocean report recommended values from Handbook N400

are used /2/.

The deck level for the structure is at z=64m

Basis wind speed for 50y return period at z=10m: vb0=26m/s for an averaging period of 10min.

Roughness for perpendicular wind assumed z0=0.01 based on /1/.

Table 11-1 shows wind data at deck level for 100 year return period. Conversion factors between

other return periods are shown in Table 11-2 together with key wind data.

Figure 11-1 shows the directional distribution.

Table 11-1 Wind climate (based on current known parameters).

Description Parameters Value

Return period permanent structure. - 100 y

Terrain roughness and terrain factor normal to bridge axis z0, kt 0.01 m, 0.17

Terrain roughness along bridge axis (assumed) z0, kt 0.05 m, 0.19

Density of air ρ 1.25 kg/m3

Basis wind speed, 100y Vb 27.0 m/s

Mean wind speed 10-min avg., norm. to bridge axis at z=64m,

100y

V10 40.2 m/s

Gust wind speed, normal to bridge axis at z=64m, 100y Vg 53.9 m/s

Along wind turbulence intensity, u, normal to bridge at z=64m Iu 11.4 %

Along wind turbulence intensity, u, along to bridge at z=64m Iu 14.0 %

Cross wind horizontal, v Iv 0.75*Iu

Cross wind hvertical, w Iw 0.50*Iu

Length scale, z=64m, u-component (see below). xLu 174.5m

Length scale, z=64m, v-component (see below). xLv 43.6m

Length scale, z=64m, w-component (see below). xLw 14.5m

Coherence decay parameter C See below

Flutter instability limit for complete bridge (at z= 64 m) Vcr 69.5 m/s


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Table 11-2 Key wind data for different return periods. Vb0=26m/s.

100y 50y 10y

(construction)

1y

Factor 1.000 0.963 0.869 0.720

vb(z=10m,t=10min) 27.0 m/s 26 m/s 23.5 m/s 19.4 m/s

v10(z=64m,t=10min) 40.2 m/s 38.7 m/s 34.9 m/s 28.9 m/s

vcr (z=64m, flutter) 69.5 m/s 66.9 m/s 60.4 m/s 50.0 m/s

Figure 11-1 Wind direction and wind speed /1/.

A.2 Wind climate models for the site

The wind climate models applicable for the Bjørnafjorden site are taken from N400 /2/:

10 min mean wind speed profile: 𝑉10(𝑧) = 𝑉𝑏 ∙ 𝑘𝑡 ∙ ln (𝑧

𝑧0)

Turbulence intensities: 𝑇𝐼𝑖(𝑧) =𝐼𝑖

ln (𝑧

𝑧0) i = u, v, w and Ii is given in Table 11-1

Standard deviation: 𝜎𝑖(𝑧) = 𝑇𝐼𝑖(𝑧) ∙ 𝑉10(𝑧)

Wind spectrum: 𝑓∙𝑆𝑖(𝑓)

𝜎𝑖2 =

𝜒𝑖

(1+1.5∙𝜒𝑖)5/3


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Where

Si(f) Spectral density of the fluctuating velocity component i

f frequency of velocity fluctuation

χi 𝜒𝑖 =𝐴𝑖∙𝑓∙𝑥𝐿𝑖(𝑧)

𝑉𝑚(𝑧)

xLi(z) Length scale of turb. comp. For z>zmin: xLu=100m(z/10m)0.3

Ai Constants assessed from N400 (Au = 6.8, Av = 9.4, Aw = 9.4)

Root coherence of the fluctuating components:

√𝐶𝑜ℎ𝑖(𝑓, ∆) = exp (−𝑓√ 𝑐𝑖𝑦

2 (𝑦1−𝑦2)2+ 𝑐𝑖𝑧2 (𝑧1−𝑧2)2

0.5(𝑉10(𝑧1)+𝑉10(𝑧2)))

Where

i u,v,w

c coherence decay parameters, cux = cvx = cwx = 0,

cuy = cuz = 10, cvy = cvz = cwy = 6.5 and cwz = 3.0

f frequency of fluctuation in Hz

Δj Distance between considered points in a plane perpendicular to

the direction of the mean wind.

It should be noted that in the above wind model formulations the common right handed sign

convention (according to N400) is used:

u - along wind component, v – lateral component, w-vertical component,

x – along wind flow direction, y – lateral direction and z – vertical direction.

RM Bridge uses a left-handed coordinate system, the result being a change in components:

y - vertical direction and z - lateral direction

v - vertical component and w- lateral component.

Because of the length of the structure, the whole bridge will not have the same wind speeds at the

same time. This is taken into account by increasing the coherence decay parameters cux, cvx, cwx from

0 to 10 in the analyses with longitudinal wind. Higher decay parameter results in less coherence and

therefore less response. A value of 10 is not necessarily conservative but has been chosen in this

phase of the project and will have to be thoroughly investigated during the next phase.


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A.3 References

/1/ Bridge across Bjørnafjorden. Metocean condtions. SINTEF Material and Chemistry. 2014-

05-08.

/2/ Håndbok N400. Bruprosjektering. Statens Vegvesen. Vegdirektoratet. 2015

/3/ SBT-PGR-TN-212-002 Suggestions for wind climate input - spectra and coherence. Rev A

2016.05.18


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Design Basis CH/HSL CH B.1

B. HYDROSTATIC AND HYDRODYNAMIC CLIMATE


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B.1 Wave conditions

Various sources exist for wave conditions at the bridge location. SINTEF has issued a report for this

project providing some wave and current data, see ref. /6/. Based on the performed wind simulations

(ref. NOT-KTEKA-007 Wind simulations) a fetch analysis and diffraction analysis, based on US

Army Shore Protection Manual 1984, have been performed in order to establish probable data for

wind and swell generated waves, documented in project report NOT-HYDA-011.

Based on the fetch analysis and diffraction analysis, the following wind generated directional wave

conditions have been derived at the midpoint of the bridge with basis of 10 year and 100 year wind

estimates. The estimates are calibrated against simulations from NorConsult and checked against

measured wave data.

1 year condition

1 year conditions

24.5 m/s Hs Tp

Heading (m) (s)

N 1.2 4.1

NNE 1.2 3.1

ENE 1.2 3.1

E 1.2 3.9

ESE 1.2 4.8

SSE 1.6 4.7

S 0.9 3.3

SSW 1.3 4.3

WSW 1.5 4.4

W 1.5 4.6

WNW 1.5 4.7

NNW 1.5 4.6


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10 year conditions

10 year conditions

27 m/s wind Hs Tp

Heading (m) (s)

N 1.3 5.2

NNE 1.3 4.9

ENE 1.3 5.9

E 1.3 6.3

ESE 1.3 6.2

SSE 1.7 5.4

S 1.0 4.0

SSW 1.4 5.2

WSW 1.9 5.4

W 1.9 5.6

WNW 1.9 6.0

NNW 1.6 5.8

100 year conditions

100 year conditions

33 m/s wind Hs Tp

Heading (m) (s)

N 2.0 5.2

NNE 2.0 4.9

ENE 2.0 5.9

E 2.0 6.3

ESE 2.0 6.2

SSE 1.8 5.4

S 1.5 4.0

SSW 2.3 5.2

WSW 3.0 5.4

W 3.0 5.6

WNW 3.0 6.0

NNW 2.5 5.8

It should be noted that the wave conditions are based on 1 hour average wind as this is considered to

be the averaging period that fits best with fully developed wind seas given the fetch length in the

fjord.


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To investigate if the structure is sensitive to periods not defined above a variation of Tp based on

formulas in DNV-RP-C205 should be checked.

The wind generated sea states will be run with the JONSWAP with a γ=3.3. A variation of γ in the

range of 2 – 4 should be checked. A directional spread for cosn(Θ –Θm) with n = 2- 5 will be used.

The 100 year design wind waves will be combined with swell as defined in the table below.

100 year swell conditions

Hs Tp

(m) (s)

0.4 12

0.4 13

0.4 14

0.4 15

0.4 16

0.2 17

0.2 18

0.2 19

0.2 20

For further investigations in the next phase an updated table will be used for swell waves, based on

updated and more extensive analysis performed during the late spring of 2015.

Swell is caused by offshore waves that get diffracted into the fjord. They can enter the bridge area

both through the northern and southern channel. Therefore, the effect of two simultaneous swell

wave trains should be considered.

Swell will be modeled using the Jonswap spectrum with a γ=7 and a directional spread for cosn(Θ –

Θm) with n = 10-20 will be used.


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B.2 Current

In the SINTEF report /6/. estimates for the current conditions and velocities are given based on

simulations. As a basis of design these results are used without further analysis. The data will be

updated when further information is available either as an updated report or as measurements.

Loads from current are based on two current profiles across the fjord (also shown in Figure 11-2):

1. Constant current, u, across the fjord.

2. Cross current: Constant current but in two directions 180 degrees. i.e. half

the fjord width in one direction and half the fjord width in the other

direction

Figure 11-2 Current profiles across the fjord

For cross current it may be assumed that Vc = 2/3V0.


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Until new data is received it is assumed that the current velocity is equal to the maximum velocity

for the cross current case. We consider it to be probable that large scale vortices occur in the area of

the bridge.

The current velocity, u, for different depths is assumed to vary as given in Table 11-3. Linear

interpolation may be used between the depths given in the table.

Table 11-3 Current velocity, u

Depth

(m)

Current velocity related to return period

u[m/s]

1 yera 10 year 100 year

0-5 0.50 0.60 0.70

10 0.30 0.35 0.40

20 0,23 0.25 0.27

30 0.23 0.25 0.27

50 0.17 0.21 0.25

100 0,13 0.14 0.16

150 0.13 0.14 0.16

It may be assumed that current force acts normal to the axis of the structure at any given position.

It is assumed that the same current profile is valid both for current going in and out of the fjord. This

will be updated when the final SINTEF report is available.


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B.3 Tidal variation

To estimate tidal variation, Kystverket’s measurement point in Bergen is used as reference. Then the

standard tables to transfer to secondary harbors has been used. We are using the harbor Osøyro

which is close to the bridge crossing. The correction factor (multiplication factor) from Bergen to

Osøyro is 0.81.

B.4 Tidal amplitudes

Table 11-4 Tidal amplitudes

Lowest Astronomical Tide (LAT) 0.0 m

Mean Low Water (MLW) 0,36 m

Mean Sea Level (MSL) 0,73 m

Mean High Water (MHW) 1,09 m

Highest Astronomical Tide (HAT) 1,46 m


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Water levels for given return periods

Table 11-5 Water level

Return period (years) Highest water level (m)

Lowest water level ‘(m)

1 1,62 -0,08

10 1,76 -0,18

50 1,85 -0,23

100 1,88 -0,26

10000

Not Defined Not Defined

The mean water level shall be increased with 0,8 m due to climate change where this is unfavorable.

B.5 Water density

The following density of the sea water may be assumed

Mean value 1025-1027 kg/m3


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B.6 Temperature

Extreme values for air temperature are given in NS-EN 1991-1-5.

Table 11-6 shows the assumed extreme values for water temperature.

Table 11-6 Extreme values for water temperature

Location Temperature °C

Maximum Minimum

Inside hull 20 0

Sea 10 0

Stated max and min sea temperatures can be assumed to be correlated.

The temperature gradient over the thickness of the outside walls in the hull will as a minimum be

assumed as ±10 °C. The same applies between the other cells in the structure

B.7 Marine fouling

Marine fouling is described in chapter 6.3.8 Marine Fouling (Q-M)


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Design Basis CH/HSL CH C.1

C. OTHER ENVIRONMENTAL LOADS

EARTHQUAKE

This environmental load condition is not included in the present design calculations

ICE LOADING

This environmental load condition is not included in the present design calculations

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