design criteria

Proposed Construction of Pulau Muara Besar Bridge, Road and Utilities (Tender Ref: TC 14 01 00)

Employers Requirement Section 2 - Design Criteria

Tender Documents DC/1

CONTENTS

PART Ⅰ. PREAMBLE ................................................................................................. 6

PART Ⅱ. GENERAL DESIGN REQUIREMENTS ...................................................... 8

1 INTRODUCTION ..................................................................................................................... 9 2 GENERAL REQUIREMENTS.................................................................................................. 9

2.1 Functional Requirements ................................................................................................. 9 2.1.1 Accessibility .............................................................................................................. 9 2.1.2 Weighing System...................................................................................................... 9 2.1.3 Maintenance Management System .......................................................................... 9 2.1.4 Cross Wind ............................................................................................................... 9 2.1.5 Flooding .................................................................................................................. 10

2.2 Durability Requirements ................................................................................................ 10 2.3 Aesthetical Requirements.............................................................................................. 10 2.4 Environmental Requirements ........................................................................................ 10 2.5 Safety During Construction............................................................................................ 10

3 COORDINATE SYSTEM AND DATUM ................................................................................ 11 3.1 Project Co-ordinate System........................................................................................... 11 3.2 Project Datum - Elevation E.L. ...................................................................................... 11

4 METEOROLOGICAL AND HYDROLOGICAL PARAMETERS............................................. 12 4.1 Meteorological Condition ............................................................................................... 12 4.2 Hydrological Condition ................................................................................................... 12

4.2.1 Sea Rise ................................................................................................................. 12 4.2.2 Storm Surge ........................................................................................................... 12 4.2.3 Astronomical Tide Variation and Mean Sea Level .................................................. 12 4.2.4 Design Water Level ................................................................................................ 13 4.2.5 Wave Heights and Period ....................................................................................... 13 4.2.6 Current .................................................................................................................... 13

5 GEOMETRICAL REQUIREMENTS ...................................................................................... 14 5.1 Alignment and Profile .................................................................................................... 14

5.1.1 Alignment Reference Point ..................................................................................... 14 5.1.2 Profile Reference Point .......................................................................................... 14

5.2 Typical Cross Section .................................................................................................... 14 5.3 Bridge Clearance ........................................................................................................... 15

5.3.1 Clearances of Main Spans for Navigation .............................................................. 15 5.3.2 Navigational Warning Light .................................................................................... 15 5.3.3 Soffit Clearance ...................................................................................................... 15




5.4 Public Utilities ................................................................................................................ 16 5.4.1 Water Supply Pipelines .......................................................................................... 16 5.4.2 Power Supply Cables ............................................................................................. 16 5.4.3 Telecommunication Cables .................................................................................... 16

PART Ⅲ. ROAD DESIGN ....................................................................................... 17

1 INTRODUCTION ................................................................................................................... 18 2 FUNCTIONAL & GEOMETRICAL REQUIREMENTS ........................................................... 18

2.1 Road Classification ........................................................................................................ 18 2.2 Traffic Data .................................................................................................................... 18 2.3 Design Speed ................................................................................................................ 18 2.4 Alignment & Profile ........................................................................................................ 18

2.4.1 Crossfall and Superelevation ................................................................................. 18 2.4.2 Horizontal and Vertical Profile Parameters ............................................................ 18

3 ROAD DESIGN ...................................................................................................................... 19 3.1 The Purpose of Road .................................................................................................... 19 3.2 Pavement Design .......................................................................................................... 19 3.3 Drainage Design ............................................................................................................ 19 3.4 Intersection .................................................................................................................... 19

PART Ⅳ. BRIDGE DESIGN .................................................................................... 20

1 GENERAL .............................................................................................................................. 21 1.1 Design Standards and Manuals .................................................................................... 21 1.2 Design Criteria ............................................................................................................... 23

1.2.1 Ultimate Limit State ................................................................................................ 23 1.2.2 Serviceability Limit State ........................................................................................ 23

1.3 Reliability Management ................................................................................................. 23 1.4 Design Life ..................................................................................................................... 24

2 DESIGN LOADING ................................................................................................................ 25 2.1 Permanent Loads .......................................................................................................... 25

2.1.1 Self Weight ............................................................................................................. 25 2.1.2 Superimposed Dead Loads .................................................................................... 25 2.1.3 Earth Pressure Loads ............................................................................................. 26 2.1.4 Differential Settlements .......................................................................................... 26 2.1.5 Creep and Shrinkage ............................................................................................. 26 2.1.6 Prestressing Force ................................................................................................. 26

2.2 Traffic Loads .................................................................................................................. 26 2.2.1 Number and Width of Notional Lanes .................................................................... 26 2.2.2 Vertical Loads ......................................................................................................... 26 2.2.3 Horizontal Loads .................................................................................................... 27




2.2.4 Groups of Traffic Loads .......................................................................................... 27 2.3 Environmental Loading .................................................................................................. 28

2.3.1 Wave Loads ............................................................................................................ 28 2.3.2 Wind Loads............................................................................................................. 28 2.3.3 Temperature Loads ................................................................................................ 31 2.3.4 Seismic Loads ........................................................................................................ 31

2.4 Accidental Loads ........................................................................................................... 33 2.4.1 Vessel Collision ...................................................................................................... 33 2.4.2 Collision with Vehicle Restrain Systems ................................................................ 34

2.5 Actions on Structures Exposed to Fire .......................................................................... 34 2.6 Actions during Execution ............................................................................................... 34

3 LOAD COMBINATIONS ........................................................................................................ 35 3.1 Ultimate Limit State ....................................................................................................... 35

3.1.1 Load Combination Rules ........................................................................................ 35 3.1.2 Combination Factor ................................................................................................ 36 3.1.3 Partial Load Factor ................................................................................................. 37 3.1.4 Design Load Combinations .................................................................................... 38

3.2 Serviceability Limit State ............................................................................................... 40 3.2.1 Load Combination Rule .......................................................................................... 40 3.2.2 Combination Factor ................................................................................................ 40 3.2.3 Design Load Combinations .................................................................................... 41 3.2.4 Serviceability Performance Requirement ............................................................... 42

3.3 Fatigue Verification ........................................................................................................ 42 4 DESIGN OF STRUCTURAL ELEMENTS ............................................................................. 43

4.1 Structural Analysis ......................................................................................................... 43 4.2 Steel Structures ............................................................................................................. 43

4.2.1 Partial Safety Factors ............................................................................................. 43 4.2.2 Material Properties ................................................................................................. 43

4.3 Concrete Structures ....................................................................................................... 43 4.3.1 Partial Safety Factors ............................................................................................. 43 4.3.2 Material Properties ................................................................................................. 44 4.3.3 Stress Limit ............................................................................................................. 44 4.3.4 Exposure Class and Nominal Cover ...................................................................... 44 4.3.5 Crack Width ............................................................................................................ 45

4.4 Foundation ..................................................................................................................... 45 4.4.1 General ................................................................................................................... 45 4.4.2 Partial Load Factor ................................................................................................. 45 4.4.3 Partial Safety Factor ............................................................................................... 45 4.4.4 Scour ...................................................................................................................... 46




4.5 Aerodynamic Stability .................................................................................................... 46 4.6 Miscellaneous ................................................................................................................ 46

4.6.1 Bearings ................................................................................................................. 46 4.6.2 Expansion Joints .................................................................................................... 46 4.6.3 Drainage ................................................................................................................. 47

4.7 Special Consideration .................................................................................................... 47 4.7.1 Durability ................................................................................................................. 47 4.7.2 Maintenance and Inspection .................................................................................. 48 4.7.3 Electrical System including Lighting ....................................................................... 49

PART Ⅴ. UTILITY DESIGN ...................................................................................... 50

1 WATER SUPPLY ................................................................................................................... 51 1.1 Introduction .................................................................................................................... 51 1.2 Treated Water Supply Design ....................................................................................... 51

1.2.1 The Purpose for Treated Water Supply .................................................................. 51 1.2.2 Tapping Point .......................................................................................................... 51 1.2.3 Pumping Station ..................................................................................................... 51 1.2.4 Elevated Water Tank in PMB .................................................................................. 51

1.3 Untreated/Raw Water Supply Design ............................................................................ 51 1.3.1 The Purpose of Untreated/Raw Water Supply ....................................................... 51 1.3.2 Untreated/Raw Water Source and Amount ............................................................ 51

1.4 Design criteria ................................................................................................................ 51 1.4.1 Roughness Coefficient ........................................................................................... 51 1.4.2 Pipeline Pressure ................................................................................................... 52 1.4.3 Pipeline Velocity ..................................................................................................... 52 1.4.4 Sluice Valves .......................................................................................................... 52 1.4.5 Washout Valves ...................................................................................................... 52 1.4.6 Air Valves ................................................................................................................ 52 1.4.7 Depth of Cover ....................................................................................................... 52 1.4.8 Thrust Blocks .......................................................................................................... 52 1.4.9 Pumping Capacity .................................................................................................. 52 1.4.10 Class of pipe ........................................................................................................... 53

2 POWER ................................................................................................................................. 54 2.1 The Purpose of Power Supply ....................................................................................... 54 2.2 Power Supply Source .................................................................................................... 54 2.3 Cabling........................................................................................................................... 54 2.4 PMB Sub-Station ........................................................................................................... 54 2.5 Low Voltage (LV) Distribution ........................................................................................ 54

3 TELECOMMUNICATION....................................................................................................... 55 3.1 The Purpose of Telecommunication Service................................................................. 55




3.2 Connection Points ......................................................................................................... 55 3.3 Cabling........................................................................................................................... 55 3.4 Distribution ..................................................................................................................... 55




PART Ⅰ. PREAMBLE




PART Ⅰ. PREAMBLE

These Design Criteria state the design requirements and design standards to be used for the structural design of the Pulau Muara Besar Bridge, Road and Utilities (hereinafter the project). Additional standards and specifications required for the design are given in the relevant sections.

The Design Criteria comprises the following parts:

Part.I : Preamble

Part.II : General Design Requirements

Part.III : Road Design

Part.IV : Bridge Design

Part.V : Utility Design

In case of any discrepancy between the requirements of the Design Criteria and any relevant technical standards, the documents shall take precedence indicated in clause “1.3 General Obligations, (26) Relevant technical standards to be applied to the Project” of “Part 4. Employer’s Requirements”.




PART Ⅱ. GENERAL DESIGN REQUIREMENTS




PART Ⅱ. GENERAL DESIGN REQUIREMENTS

1 INTRODUCTION

PART Ⅱ of the Design Criteria specifies general requirements for the design and construction of

the PMB Bridge, Road and Utilities such as functional, aesthetical, environmental, durability and maintenance requirements and specific geometrical requirements to be complied with. Major design basis parameters are also included in the PART Ⅱ.

These General Requirements shall be read in connection with the Employer's Concept Design drawings.

2 GENERAL REQUIREMENTS

2.1 Functional Requirements

2.1.1 Accessibility The PMB Bridge shall be open to traffic 24 hours a day all year round. The design shall take into consideration that regular maintenance operations and maintenance repairs can take place while the PMB Bridge is in operation.

2.1.2 Weighing System The PMB Bridge shall be provided with weighing system to facilitate check of truck loadings before passing the bridge. The weighing system shall be located in the starting and ending points of the PMB Bridge.

2.1.3 Maintenance Management System The maintenance management system shall be provided for a fully operation and maintenance of the entire PMB Bridge, Road and Utilities. The following systems, which are significant and important for the road users, shall be provided:

Road lighting providing good visibility of possible obstacles on the carriageways and raising comfort of driving along the bridge and road during the night.

Traffic management system including incident management system and traffic control system for control of the traffic and traveler guidance and information on services which are available along the bridge and road.

Maintenance management system.

Furthermore, management office including a control room for the bridge and road monitoring shall be provided on the PMB. The Contractor shall propose the location of the management building for the Employer's review.

2.1.4 Cross Wind The road traffic is composed of vehicles with widely varying wind sensitivity and maneuverability. Experience from exposed roadways indicates that light vehicles may overturn in high winds. Closing of the bridge for road traffic due to severe crosswind conditions shall be kept at a minimum.

The following elements and measures shall be considered:




- traffic control systems to be implemented including an integral system such as reduced speed for light and wind sensitive vehicles during periods with high wind speeds, redirection of these cars in case of extreme winds or for other reasons,

- shaping of the superstructure and crash barrier to reduce disturbing crosswind effects on vehicles on the road,

- limit the number of large structural elements giving transitory shelter effects.

2.1.5 Flooding Flooding of the bridge from extreme rainfalls shall be prevented by provision of suitable designs, adequately elevated and provided with suitable run-off and drainage arrangements.

2.2 Durability Requirements The PMB Bridge shall be designed to be kept in operation for at least 100 years.

Main structural elements shall be designed to be in operation for 100 years assuming that no structural elements need to be replaced (assuming normal maintenance standard) within this period as a result of normal degradation, i.e. the service life must be 100 years. Examples of main structural elements are bridge decks, piers and foundations.

Elements of the PMB Bridge and Road, which are exposed to significant wear or degradation such as wearing course, barriers, bearings, expansion joints etc., may be designed for a service life less than 100 years. For such elements a cost optimal service life must be sought and the PMB Bridge designed for easy replacement of such elements. Minimum design life for each element is specified in Clause 1.4 of PART Ⅳ.Bridge Design.

All structures shall be arranged so that they can be easy to inspect and maintain. The structures shall be arranged so that good run-off can be facilitated and accumulation of dust and water is minimized.

2.3 Aesthetical Requirements The design of the PMB Bridge shall be harmonized with surroundings of the project site.

2.4 Environmental Requirements The PMB Bridge is located in a highly sensitive marine environment. It shall be documented that the design and construction of the bridge shall result in only minor temporary and insignificant permanent impacts to the environment.

An Environmental Impact Assessment (EIA) has been prepared for cable stayed bridge as the main bridge. The Contractor must comply with the requirements and assumptions of the EIA and is required to submit further details for the design and construction to the Department of Environment, Parks and Recreation (JASTRE). Details are described in the Employer's Requirements. The Contractor shall also submit the Environmental Monitoring Plan for the project.

2.5 Safety During Construction The safety during construction of the PMB Bridge shall be documented by the Contractor in accordance with the standards, guidelines referenced in the relevant general design specifications applied to each part of the Design Criteria as appropriate.

The Contractor shall submit his design of temporary works to the Engineer for review according to the agreed program for construction.




3 COORDINATE SYSTEM AND DATUM

3.1 Project Co-ordinate System The Borneo Rectified Skew Orthomorphic (BRSO) projection parameters have been chosen as the Project Coordinate System in order to facilitate interfaces with the Engineering Infrastructure Development Plan, other infrastructure projects and existing databases.

3.2 Project Datum - Elevation E.L. The Brunei Standard Datum (BSD88) is generally applied by all authorities and private developer in Brunei for construction projects on land. Therefore, the BSD88 has been chosen as the Project Datum instead of Chart Datum (CD).

With regard to the bathymetry (water depth in the Brunei Bay), the following datum has been used in the Employer's Concept Design Drawing:

At Muara Port : 2010/12 (513 days)

CD

Highest Astronomical Tide (HAT) : 2.65m 1.28 m

BSD88

Mean Higher High Water (MHHW) : 2.39m 1.02 m

Mean Lower High Water (MLHW) : 1.77m 0.40 m

Mean Sea Level (MSL) : 1.37m 0.00 m

Mean Higher Low Water (MHLW) : 0.96m -0.41 m

Mean Lower Low Water (MLLW) : 0.34m -1.03 m

Lowest Astronomical Tide (LAT) : 0.00m -1.37 m

Note: These values are obtained from Marine Department in Brunei.

The vertical level comparison between Chart Datum (CD) and BSD88 is shown in below figure for reference.

Figure II-3.1 Vertical level comparison diagram (indicative only)




4 METEOROLOGICAL AND HYDROLOGICAL PARAMETERS

The various studies have been carried out by the Employer for the assessment of the meteorological and hydrological condition. The criteria in this section should be read with the following documents:

Volume IV : Appendix 3C Met-Ocean Study

Appendix 3E Scour Study

4.1 Meteorological Condition Design wind velocities for various return periods are given in Table II-4.1 below as the mean velocity measured at 10m height above sea level.

Table II-4.1 Design Wind Velocity

Return Period (years)

Wind Speed (m/s) (mean 10-minutes)

Wind Gust (m/s) (mean 3-seconds)

1 15.1 21.0

5 16.8 23.2

10 18.0 25.0

50 20.5 28.6

100 21.5 29.9

When assessing wind conditions for other locations above water, the Contractor shall take into consideration the terrain roughness and orography.

When required in the design, wind speeds for other return periods and heights shall be assessed by the Contractor.

4.2 Hydrological Condition

4.2.1 Sea Rise The latest report provided by the Intergovernmental Panel on Climate Change (IPCC) estimated that the sea level rise will be 18 to 59cm as a result of the greenhouse effect by global economic growth. In this project, an expected sea level rise can be taken as 0.4m

The sea level rise shall be included in the design for offshore structures.

4.2.2 Storm Surge The set-up and set-down storm surges due to typhoon can be taken as 0.14m and -0.25m for 100-year return period, respectively.

Maximum surge current for 100-year return period is 0.50m/s.

4.2.3 Astronomical Tide Variation and Mean Sea Level

The astronomical tide variations are specified in Clause 3.2 of PART-Ⅱ.




4.2.4 Design Water Level The design high water levels (DHWL) is defined as

DHWL = MHHW + Storm surge + Sea level rise

4.2.5 Wave Heights and Period Wave heights and periods at different locations along the bridge alignment will be a function of bathymetry, water level, wind direction and wind speed.

The return period values of significant wave height (Hm0), associated peak wave period (Tp), and the most probable maximum single wave crest (Cmax) and height (Hmax) are provided in Table II-4.2.

Table II-4.2 Design significant wave height, peak wave period, wave crest and maximum wave height at point P1, P2, P3, and P4.

Return Periods

Parameters P1 P2 P3 P4

1

0.3 (m) 0.3 0.3 0.3

1.5~2.5 (sec) 1.5~2.5 1.5~2.5 1.5~2.5

0.3 (m) 0.3 0.3 0.4

0.5 (m) 0.5 0.6 0.6

5

0.3 (m) 0.3 0.3 0.4

1.5~2.5 (sec) 1.5~2.5 1.5~2.5 2.0~2.5

0.4 (m) 0.4 0.4 0.4

0.6 (m) 0.6 0.6 0.7

10

0.3 (m) 0.3 0.4 0.4

1.5~2.5 (sec) 1.5~2.5 2.0~2.5 2.0~2.5

0.4 (m) 0.4 0.4 0.5

0.6 (m) 0.6 0.7 0.7

50

0.4 (m) 0.4 0.4 0.4

1.5~2.5 (sec) 2.0~2.5 2.0~2.5 2.0~2.5

0.5 (m) 0.4 0.5 0.5

0.7 (m) 0.7 0.7 0.7

100

0.4 (m) 0.4 0.4 0.4

1.5~2.5 (sec) 2.0~2.5 2.0~2.5 2.0~2.5

0.5 (m) 0.5 0.5 0.5

0.7 (m) 0.7 0.8 0.8

* Note : For location of P1~P4, refer to Appendix 3C – Met-Ocean Study of Volume IV.

4.2.6 Current The mean design current to be applied for scour evaluation can be taken as 1.2m/s. The Contractor shall evaluate and take into consideration any effects that might result in higher local current speeds and affect the scour potential.




5 GEOMETRICAL REQUIREMENTS

5.1 Alignment and Profile Alignment is made to the Site Boundary drawings.

5.1.1 Alignment Reference Point The reference point for the horizontal alignment is the center of the entire cross section.

5.1.2 Profile Reference Point The reference point for the horizontal and vertical profiles (Theoretical Gradient Line - TGL) is the center of the entire cross section, where the top level of asphalt from the two adjacent carriageways meet as shown in Figure II-5.1.

Figure II-5.1 Reference Point for Profile

The longitudinal profile shall comply with the design requirements for the access roads, the requirements for soffit clearance and vertical navigation clearance.

5.2 Typical Cross Section Between inner sides of the traffic railings the roadway shall accommodate lanes and provisions in accordance with Geometric Design Guidelines for Road in Brunei Darussalam. The requirements for roadway cross section are outlined in Table II-5.1.

Table II-5.1 Roadway Cross Section Requirements

Classification Width

Bridge Road

Traffic lane 3.65 m 3.65 m

Hard shoulder 3.00 m 3.00 m

Inner shoulder 0.50 m 0.50 m

Median 1.00 m 1.00~4.00 m

The vertical clearance above the carriageway shall be minimum 5.4m.

Typical road cross sections in bridge and road are shown in Figure II-5.2.

TGL"E" LINE"W" LINE

CL of ROAD




(a) Bridge

(b) Road

Figure II-5.2 Typical Cross Section

5.3 Bridge Clearance

5.3.1 Clearances of Main Spans for Navigation For bridge span crossing the navigation channel, the clearances shall fulfill the following requirements.

Minimum Horizontal Clearance (B) : 120m

Minimum Vertical Soffit Clearance (H) : 28m

The minimum vertical soffit clearance for navigation of standard vessel is relative to Mean Higher High Water (MHHW). The horizontal clearance of the navigation channel shall be maximised to secure the safety of vessel navigation within span length of the main bridge.

The Contractor shall review these clearances by navigational studies including but not limited to international rules, ship handling study, etc., and determine the clearances finally after getting approvals from the relevant authorities after award of the Tender.

5.3.2 Navigational Warning Light Navigational warning lights for vessel traffic shall be provided for the bridge in accordance with the maritime navigation buoyage system recommendations and the requirements of the Brunei Marine Department.

5.3.3 Soffit Clearance For the bridge deck over water, the soffit level in case of not taking vertical clearance of vessel navigation into consideration shall be assessed as follows:

Soffit level > DHWL +

where,

+ WSSH + FB

DHWL Design High Water Level

CL of Bridge Deck

500 3000 2@3,650=7,300 2000 2@3,650=7,300 3000 500

23600

2.5% 2.5%

Carriage WayShoulder Median Carriage Way Shoulder

Carriage WayCarriage Way Median Carriage Way Carriage Way

2.5% 2.5%

300020003500

5,00020,000 LANDSCAPECORRIDOR

3000 2000 7550

CL of Road LIMIT OFCONSTRUCTION BOUNDARY

SEWERAGESERVICES

DRAINRESERVE SERVICES RESERVEDRAIN

RESERVESERVICES RESERVE

PIPERACKSLIMIT OF

CONSTRUCTION BOUNDARY

3000 2@3650=7300 500 4000 30002@3650=7300500

25600

2000 20000LANDSCAPECORRIDOR




WSSH Water Spray & Splash Height (=2.0m)

Maximum wave height

FB Freeboard (=1.0m)

For the bridge deck over arterial roads, the soffit level shall be at least 5.4m.

5.4 Public Utilities

5.4.1 Water Supply Pipelines The Contractor shall consider any requirements for water supply pipelines on the PMB Bridge. Space and load requirements shall be established as part of the design activity. Suitable access for inspection, repair and replacements shall be also provided. The Contractor shall listen to the relevant authorities' opinions and adjust the final design if any changes occur.

5.4.2 Power Supply Cables The Contractor shall consider any requirements for power supply cables on the PMB Bridge. Space and load requirements shall be established as part of the design activity. Suitable access for inspection, repair and replacements shall be also provided. The Contractor shall listen to the relevant authorities' opinions and adjust the final design if any changes occur.

5.4.3 Telecommunication Cables The Contractor shall consider any requirements for telecommunication cables on the PMB Bridge. Space and load requirements shall be established as part of the design activity. Suitable access for inspection, repair and replacements shall be provided. The Contractor shall listen to the relevant authorities' opinions and adjust the final design if any changes occur.




PART Ⅲ. ROAD DESIGN




PART Ⅲ. ROAD DESIGN

1 INTRODUCTION

Part 3 of the Design Criteria specifies issues of importance for the design of roads.

The General Design Specifications for roads are as follows:

Geometric Design Guidelines for Roads (GD15) General Specification for Road Furniture (GS2:1998) General Specification for Earthwork (GS4:1999) General Specification for Road Traffic Signs (GS8:2000) Design Manual for Road and Bridges (DMRB), The Highways Agency of Department

for Transport, UK

2 FUNCTIONAL & GEOMETRICAL REQUIREMENTS

2.1 Road Classification The PMB Bridge and Road is classified as a Primary Road in the Brunei Road System.

2.2 Traffic Data The Contractor shall base his road and intersection design on traffic forecasts for 20 years.

2.3 Design Speed The design speed for this project is 100 km/h. For access roads, the design speed shall be established depending on location and physical constraints.

2.4 Alignment & Profile

2.4.1 Crossfall and Superelevation Considering the Brunei standards and relevant specifications, crossfall and superelevation have been defined on the Employer's Concept Design drawings.

Unless otherwise defined on the alignment drawings, crossfall and superelevation shall be applied in accordance with the Geometric Design Guidelines for Roads of Brunei.

2.4.2 Horizontal and Vertical Profile Parameters The horizontal and vertical profile shall be applied to road and bridge. And the horizontal and vertical profile shall comply with the design requirements for the following tables.

Table III-2.1 Minimum Values of Vertical Profile Parameters

Category Desirable Absolute

Minimum vertical radius, crest 60m/% 55m/%

Minimum vertical radius, sag 40m/% 36m/%

Maximum gradient 4% 6%




No minimum gradient is required for the Project. For drainage purpose, the minimum gradient is 0.5%.

Table III-2.2 Minimum Values of Horizontal Profile Parameters

Category Desirable Absolute

Horizontal curvature 550m 340m

Spiral length regardless of superelevation 55m 55m

3 ROAD DESIGN

3.1 The Purpose of Road The purpose of the road scope is to safely, efficiently, and effectively provide connectivity for the transportation of heavy vehicles and machinery and also for people, cargo, goods, products, services and utilities which include electrical cables (high and low voltage), telecommunication lines, raw water pipe, treated water pipe, and sewerage pipe during its design life.

3.2 Pavement Design The pavement shall be designed in accordance with the Eurocode and the following specifications:

General Specification for Flexible Pavement (GS1:1998) General Specification for Pavement Stabilization Design Manual for Road and Bridges, Vol.7 Pavement Design and Maintenance

The Highway Agency of Department for Transport, UK

The Contractor shall take into consideration the hot climate condition, the ground condition with soft clay, the predicted traffic intensities and actual traffic loads in the design of the pavement. The pavement live loads shall be the same as those used for the bridge structures - See Part 4.

The Contractor shall use lifetime assessments of the pavement in order to choose the optimal design.

3.3 Drainage Design The drainage shall be designed in accordance with the Eurocode and the following specifications:

General Specification for Drainage Works (GS5:1999)

3.4 Intersection Intersections shall be designed to match forecast design. They work most efficiently when traffic flows are reasonably balanced between the arms, having taken into account the traffic assessment criteria. Design of intersection shall be based on 'Design Manual for Roads and Bridge, Vol. 6' of The Highway Agency of Department for Transport, UK.




PART Ⅳ. BRIDGE DESIGN




PART Ⅳ. BRIDGE DESIGN

1 GENERAL

The design criteria contain complements and modifications to the design standards and manuals given in Clause 1.1 and shall be applied for the design of the PMB Bridge. Eurocodes have been adopted as the design standard for the PMB Bridge, and UK National Annex is not applicable unless otherwise specified in these design criteria.

The purpose of the bridge is to link the mainland (at Kampong Serasa) to PMB to safely, efficiently, and effectively provide connectivity for the transportation of heavy vehicles and machinery and also for people, cargo, goods, products, services and utilities which include electrical cables (high and low voltage), telecommunication lines, raw water pipe, treated water pipe, and sewerage pipe.

1.1 Design Standards and Manuals The design criteria given in this document follow the requirement as set forth in the following design documents and form the basis for design. Additional standards and specifications required for the design will be given in the relevant sections of these design criteria.

BS EN 1990:2002 Eurocode : Basis of structural design

British Standard : Eurocode

BS EN 1991-1-1:2002 Eurocode 1 : Actions on structures - Part 1-1:

General Actions : Densities, self-weight, imposed load for building


General Actions : Actions on structures exposed to fire


General Actions : Wind actions


General Actions : Thermal actions


General Actions : Actions during execution


General Actions : Accidental actions

BS EN 1991-2:2003 Eurocode 1 : Actions on structures - Part 2 : Traffic loads on bridges

BS EN 1992-1-1:2004 Eurocode 2 : Design of concrete structures - Part 1-1:

General rules and rules for buildings

BS EN 1992-2:2005 Eurocode 2 : Design of concrete structures - Part 2:

Concrete bridges - Design and detailing rules

BS EN 1992-3:2006 Eurocode 2 : Design of concrete structures - Part 3:

Liquid retaining and containment structures

BS EN 1993-1-1:2005 Eurocode 3 : Design of steel structures - Part 1-1:

General rule and rule for building




BS EN 1993-1-5:2006 Eurocode 3 : Design of steel structures - Part 1-5:

Plated structural elements

BS EN 1993-1-9:2005 Eurocode 3 : Design of steel structures - Part 1-9: Fatigue

BS EN 1993-2:2006 Eurocode 3 : Design of steel structures - Part 2: Steel bridges

BS EN 1993-5:2007 Eurocode 3 : Design of steel structures - Part 5: Piling

BS EN 1994-1:2004 Eurocode 4 : Design of composite steel and concrete structures -

Part 1-1: General rules and rules for buildings

BS EN 1994-2:2005 Eurocode 4 : Design of composite steel and concrete structures -

Part 2: General rules and rules for bridges

BS EN 1997-1:2004 Eurocode 7 : Geotechnical design - Part 1: General rules

BS EN 1997-2:2007 Eurocode 7 : Geotechnical design - Part 2 : Ground investigation

and testing

BS EN 1998-1:2004 Eurocode 8 : Design of structures for earthquake resistance -

Part 1: General rules, seismic actions and rules for buildings


Part 2: Bridges


Part 5: Foundations, retaining structures and geotechnical aspects

EN 197-1:2000 Cement - Part 1: Composition, specifications and conformity criteria

Other European Standards

for comment cements

EN 206-1:2000 Concrete - Part 1: Specification, performance, production

and conformity

EN 13670:2009 Execution of concrete structures

EN 15050:2007 Precast concrete products - Bridge elements

EN 10079:2007 Definition of steel products

EN 10080:2005 Steel for the reinforcement of concrete -

Weldable reinforcing steel - General

EN 10138-1:2000 Prestressing steels - Part 1: General requirements

EN 10138-2:2000 Prestressing steels - Part 2: Wire

EN 10138-3:2000 Prestressing steels - Part 3: Strand

EN 10138-4:2000 Prestressing steels - Part 4: Bars

EN 10244-1:2009 Steel wire and wire products - Non-ferrous metallic coatings on steel

wire - Part 1: General principles

EN 10244-2:2009 Steel wire and wire products - Non-ferrous metallic coatings on steel

wire - Part 2: Zinc or zinc alloy coatings

EN 1090-1:2009 Execution of steel structures and aluminium structures - Part 1:

Requirements for conformity assessment of structural components

EN 1090-2:2009 Execution of steel structures and aluminium structures - Part 2:




Technical requirements for steel structures.

EN 10025-1:2004 Hot rolled products of structural steels - Part 1: General technical

delivery conditions

EN 1317 Road restraint systems

EN 1337 Structural bearings

EN ISO 12944-1 Paints and varnishes - Corrosion protection of steel structures by

protective paint systems - Part 1: General introduction

EN ISO 12944-2 Paints and varnishes - Corrosion protection of steel structures by

protective paint system - Part 2: Classification of environments

Design Manual for Roads and Bridges, The Highway Agency of Department for Transport, UK

Other International Standards and Design Manuals

AASHTO LRFD Bridge Design Specifications, 4th Edition, 2007

AASHTO Guide Specification and Commentary for Vessel Collision Design of Highway Bridges Volume I : Final Report (1991)

CEB/FIB Model Code 1990

1.2 Design Criteria Ultimate and serviceability limit states as specified in Eurocode shall constitute the basis of design and analysis.

1.2.1 Ultimate Limit State The limit states that concern the safety of people, and/or the safety of the structure shall be classified as ultimate limit state.

The following ultimate limit states shall be verified where they are relevant:

loss of equilibrium of the structure or any part of it, considered as a rigid body ; failure by excessive deformation, transformation of the structure or any part of it into a

mechanism, rupture, loss of stability of the structure or any part of it, including supports and foundations ;

failure caused by fatigue or other time-dependent effects.

1.2.2 Serviceability Limit State The limit states that concern:

the functioning of the structure or structural members under normal use ; the comfort of people ; the appearance of the construction works,

shall be classified as serviceability limit states.

The verification of serviceability limit states shall be based on criteria concerning the following aspects :

deformations ; vibrations ; damage that is likely to adversely affect.

1.3 Reliability Management




The PMB Bridge can be categorized as medium consequence class CC2, and the multiplication factor

1.4 Design Life

may be taken as 1.0. Considering the importance of this Project in Brunei, however, Design Supervision Level DSL3 and Inspection Level IL3 shall apply.

The design life is the period for which the structures are to be used for their intended purposes with anticipated maintenance, but without loss of reliability or structural, operational and aesthetic integrity. The full service life is required for the main structural components such as piles, abutments, piers, bridge decks, etc. Some elements will require replacement during the design life of the bridge such as bearing, expansion joint, etc.

Design life of structural elements, which cannot be replaced, shall be a minimum of 100 years except as otherwise specified in Table IV-1.1.

For the replaceable elements, the following minimum design life shall be secured with appropriate maintenance strategies.

Table IV-1.1 Minimum Design Life for Replaceable Elements

Category Element Minimum Design Life (Year)

1 Bearing, Expansion joint, Parapet,

Railing, Bridge deck waterproofing and base course 50

2 Drainage system, etc. 40

3 Bridge deck wearing course 20

4 Temporary structure, Road marking 10




2 DESIGN LOADING

2.1 Permanent Loads Permanent loads for the bridge include self weight of the structures, superimposed dead loads, construction tolerance and differential settlements. The characteristic values of permanent loads shall be determined in accordance with BS EN 1991-1-1.

2.1.1 Self Weight Self weight will include the weights of the materials and parts of the structure that is structural and permanent in nature. Unit weight to materials is assumed as follows:

Table IV-2.1 Unit density of materials

Material Description Density (kN/

Concrete

)

Reinforced concrete / Prestressed concrete 25.0

Concrete 24.0

Steel Structural, prestressed and ordinary reinforcement 77.0

2.1.2 Superimposed Dead Loads The superimposed dead loads that the structure has to sustain include the wearing surface (pavement), parapets, safety barriers, etc. The following value can be applied for the unit weight of wearing surface:

- Wearing surface : 23kN/

The weight of utility services such as water pipes (including weight of water), power cables, lighting and telecommunication, etc shall be included in the design load of the bridge. A minimum nominal load intensity of 85kN/m, distributed evenly about the centerline of the bridge, shall be used in the global analysis. This load is preliminary and the Contractor shall allow for the weight of utility and services on the PMB Bridge and provide a reasonable load add-on for future upgrading of these if more accurate data are available and indicate that the 85kN/m is insufficient. This preliminary load is based on the following estimation:

- Water supply facilities for treated/untreated water pipe : 12 kN/m

- Water supply facilities for future sewage pipe : 8 kN/m

- Power supply facility (BPMC’s requirement) : 40 kN/m

- Power supply facility (DES’s requirement) : 15 kN/m

- Telecommunication facility : 5 kN/m

- Additional allowance : 5 kN/m

- Total load intensity : 85 kN/m

Other superimposed dead loads including vehicle restraint systems, kerbs, etc shall be determined based on actual dimensions and the densities given in Table IV-2.1.




2.1.3 Earth Pressure Loads Earth pressure loads shall be determined in accordance with BS EN 1997 using the relevant soil properties.

2.1.4 Differential Settlements The effect of differential settlements and/or movements of the support due to soil subsidence shall be classified as a permanent action and appropriately estimated values of predicted settlements should be used.

The Contractor shall estimate the total and differential settlement of the foundations and take this into account in the design.

The following additional allowance for differential settlements and rotations in excess of the predicted settlements shall be taken into account for foundation movements.

Differential settlement : 10mm

Differential rotation : 1/2000

2.1.5 Creep and Shrinkage Creep and shrinkage effects shall be calculated in accordance with BS EN 1992 and the recommendations of the CEB-FIP 1990 Model Code, and it shall be considered as permanent load. The average relative humidity ratio can be taken as 85%.

2.1.6 Prestressing Force Prestressing force shall be classified as a permanent action caused by either controlled forces and/or controlled deformations imposed on a structure in accordance with Clause 4.1.2(6) of BS EN 1990. Prestressing forces shall be determined in accordance with BS EN 1992.

2.2 Traffic Loads Traffic loads shall be in accordance with BS EN 1991-2 except as described otherwise below.

2.2.1 Number and Width of Notional Lanes According to Clause 4.2.3(1) of BS EN 1991-2, the carriageway width should be measured between kerbs or between the inner limits of vehicle restraint systems. For each 11m wide carriageway, the number of notional lands (n1) shall be defined as n1=Int(11/3)=3 in accordance with the principles specified in Table 4.1 of BS EN 1991-2. Also, the width of a notional lane (w1) is 3.0m. The location and numbering of the lanes should be determined in accordance with Clause 4.2.4 of BS EN 1992.

2.2.2 Vertical Loads Characteristic loads are intended for the determination of road traffic effects associated with ultimate limit state verifications and with particular serviceability verification. The vertical load models comprise Load Model 1~4.

2.2.2.1 Load Model 1

Load Model 1 (LM1) consists of two partial system : Tandem system (TS) and Uniformly distributed loads (UDL). The details of Load Model 1 are illustrated in Table IV-2.2.

As noted in Clause 4.1(1) of BS EN 1991-2, Load Model 1 should be used for the design of road bridges with loaded lengths less than 200m, and load models for loaded lengths greater than 200m shall be defined for the individual project.




For loaded lengths greater than 200m, the Contractor shall provide a reasonable value from the evaluation of the live load model based on expected traffic data for the bridge.

Table IV-2.2 Load Model 1 (LM1)

Load model Characteristic values

Location TS: UDL:(kN) (kN/

Notional lane 1

)

300 9.0

Notional lane 2 200 2.5

Notional lane 3 100 2.5

Other lanes 0 2.5

Remaining area 0 2.5

2.2.2.2 Load Model 2

Load Model 2 consists of a single axle load akQ0β and akQ equal to 400kN dynamic

amplification included, which shall be applied at any location on the carriageway. The value of

0β shall be taken equal to the value of 0.11 =Qα as specified in Clause 4.3.3 of BS EN 1991-

2. The contact surface of each wheel in Load Model 2 should be taken as a square of sides 0.40m. This load model shall be applicable to the design of orthotropic deck.

2.2.2.3 Load Model 3, 4

Load Model 3 (for special vehicles) and Load Model 4 (for crowd loading) are not used unless otherwise specified.

2.2.3 Horizontal Loads

2.2.3.1 Braking and Acceleration Forces

Braking and acceleration forces ( lkQ ) shall be in accordance with Clause 4.4.1 of EN 1991-2.

The characteristic value of lkQ limited to 900kN for the total width of the bridge, shall be

calculated in accordance with Eq.(4.6) of EN 1991-2.

2.2.3.2 Centrifugal Forces

Centrifugal forces ( tkQ ) shall be in accordance with Clause 4.4.2 of EN 1991-2.

2.2.3.3 Lateral Forces from Skew Braking or Skidding

According to Clause 4.4.2(4) of EN 1991-2, lateral forces from skew braking or skidding should be taken into account. A transverse braking force equal to 25% of the longitudinal braking or acceleration forces shall be considered to act simultaneously with lkQ at the finished

carriageway level.

2.2.4 Groups of Traffic Loads

2.2.4.1 Characteristic Values of the Multi-Component Action




The simultaneity of the loading systems defined in clauses 2.2.2~2.2.3 should be taken into account by considering the groups of loads defined in Table IV-2.3. Each of load groups, which are mutually exclusive, should be considered as defining a characteristic action for combination with non-traffic loads.

Table IV-2.3 Characteristic values of the multi-component action for traffic load

Load type

Carriageway Vertical forces Horizontal forces

Load system

LM1 (TS and UDL)

LM2 (Single axle)

Baking and acceleration

forces

Centrifugal and transverse forces

gr1a Characteristic gr1b Characteristic gr2 Frequent Characteristic Characteristic

2.2.4.2 Frequent Values of the Multi-Component Action

The frequent action shall consist only of either the frequent values of LM1 or LM2 without any accompanying component, as defined in Table IV-2.4 in accordance with Table 4.4b of BS EN 1991-2.

Table IV-2.4 Frequent values of the multi component action for traffic load

Load type

Carriageway Vertical Force

Load system

LM1 (TS and UDL systems)

LM2 (Single axle)

gr1a Frequent values

gr1b Frequent values

2.3 Environmental Loading

2.3.1 Wave Loads The design wave loads shall be determined corresponding to a return period of 100 years. The Contractor shall estimate the wave loads and take this into account in the design. Hydrological conditions are specified in Clause 4.2 of Part II.

2.3.2 Wind Loads The design wind loads shall be determined corresponding to a return period of 100 years in accordance with BS EN 1991-1-4. During construction, the 10 years return period can be used.

2.3.2.1 Basic Wind Velocity

The 10 minutes mean wind speed for the PMB Bridge has been estimated as 18 and 21.5m/s for 10 and 100-year return periods, respectively.

The basic wind velocity bv is the fundamental value 0,bv after application of the directional

and seasonal factors.

0,bseasondirb vccv ⋅⋅=

where, dirc : directional factor (=1.0)




seasonc : season factor (=1.0)

To verify the aerodynamic stability of the bridge during construction, the Contractor shall estimate the return period and the relevant wind velocity for the construction stage.

2.3.2.2 Mean Wind Velocity

The mean wind velocity )(zvm at a height z above the terrain depends on the terrain roughness

and orography and on the basic wind velocity.

borm vzczczv ⋅⋅= )()()(

Where, )(0 zc : orography factor (=1.0)

)(zcr : terrain roughness factor

×=

0

ln)(zzkzc rr for maxmin zzz <≤

( )min)( zczc rr = for minzz <

0z : roughness length

07.0

,0

019.0

×=

IIr z

zk where, IIz ,0 = 0.05m (terrain category II)

minz : minimum height

maxz : maximum height (=200m)

0z , minz depend on the terrain category. Recommended values are given in Table IV-2.5 depending on five representative terrain categories.

Table IV-2.5 Terrain categories and terrain parameters

Terrain category 0z (m) minz (m)

0 Sea or coastal area exposed to the open sea 0.003 1

I Lakes or flat and horizontal area with negligible vegetation and without obstacles 0.01 1

II Area with low vegetation such as grass and isolated

obstacles (tree, buildings) with separations of at least 20 obstacle heights

0.05 2

III

Area with regular cover of vegetation or buildings or with isolated obstacles with separations of maximum 20 obstacle

heights (such as villages, suburban, terrain, permanent forest)

0.3 5

IV Area in which at least 15% of the surface is covered with buildings and their average height exceeds 15m 1.0 10




2.3.2.3 Turbulence Intensity

The turbulence intensity )(zI i at any height is the standard deviation of the wind velocity

divided by the mean value. The recommended expression in the EN is given as :

−⋅

==

00

1

ln)()()(

zhz

zc

kzIzI

disui for longitudinal direction (windward)

)(8.0)()( zIzIzI uvi ⋅== for lateral direction

)(5.0)()( zIzIzI uwi ⋅== for vertical direction

2.3.2.4 Power Spectra

The power spectra of the longitudinal, lateral and vertical turbulence components shall be defined by a proven spectral model such as Von Karman, Kaimal, modified Kaimal and Davenport spectral model.

2.3.2.5 Peak Velocity Pressure

The peak velocity pressure at any height which includes mean and short-term velocity fluctuations shall be determined as follows :

[ ] )(21)(71)( 2 zvzIzq mip ⋅⋅⋅+= ρ

2.3.2.6 Force in Transverse Direction

The wind force in transverse direction (parallel to the deck width) may be obtained as follows :

refbw ACvF ⋅⋅⋅⋅= 2

21 ρ

where, ρ : density of air (=1.25kg/

)

bv : basic wind speed

C : wind load factor. fe ccC ⋅=

ec : exposure factor

fc : force(or drag) coefficient

Meanwhile, 25% of the wind force in transverse direction shall be taken into account in longitudinal direction if required.

2.3.2.7 Traffic Restriction due to Strong Wind

When a running vehicle is exposed to high side wind on the bridge, sliding between tires and road surface may occur and can lead to traffic accidents. Therefore, the Contractor should estimate the traffic safety under strong wind on the bridge and provide the windshields on the bridge if required. Also, the Contractor shall establish the traffic restriction plan according to different closure criteria for different wind speed.




2.3.3 Temperature Loads Temperature load shall be obtained in accordance with BS EN 1991-1-5 except as others described below.

2.3.3.1 Uniform Temperature Component

For the coefficient of thermal expansion, the following values will be used until material specific data are available.

Normal weight concrete : 1.0 x 10

Steel : 1.2 x 10

-5

The uniform temperature component depends on the minimum and maximum temperature which the bridge will achieve. Based on the meteorological data obtained from the Brunei International Airport station, the uniform temperature range can be taken as follows:

-5

Shade air temperature : = 38.0ºC,

According to the Figure 6.1 of BS EN 1991-1-5, the uniform bridge temperature can be taken as follows:

= 18.4ºC

Steel Elements : ,max = +55.0ºC, ,min

Concrete Elements :

= +15.0ºC

,max = +42.0ºC, ,min

The initial bridge temperature (reference temperature) at the time that the structure is restrained may be taken as +28ºC. Therefore, the characteristic value of the maximum contraction range of the uniform bridge temperature component should be taken as

= +24.0ºC

,con = - ,min. And the characteristic value of the maximum expansion range of the uniform bridge temperature component should be taken as , exp = ,max -

The maximum contraction and expansion ranges of the uniform bridge temperature component shall be taken as (

.

,con+10)ºC and ( ,exp

2.3.3.2 Temperature Gradients

+10)ºC respectively.

Temperature gradients for the superstructures shall be determined in accordance with 6.1.4 of BS EN 1991-1-5.

2.3.3.3 Difference in the Uniform Temperature between Structural Elements

Since the differences in the uniform temperature component between different types (bridge deck, etc) may cause adverse load effects on the bridge, these effects should be taken in account as follows:

ΔT = 15ºC : between main structural elements

These effects should be considered in addition to the effects resulting from a uniform temperature component in all elements.

2.3.4 Seismic Loads

2.3.4.1 Importance Factor

Since the PMB Bridge is anticipated to remain open to all traffic after the design earthquake and the bridge will be the only connecting road between the mainland and the PMB, the PMB Bridge shall be classified as "Greater than average".

a) No-collapse requirement




The structure shall be designed and constructed to withstand the design seismic action without local or global collapse, thus retaining its structural integrity and a residual bearing capacity after the seismic events.

For the design seismic action in No-collapse requirement, the probability of exceedance ( ) in 100 years is 4% and the return period (

) is 2,450 years.

The structure shall be designed and constructed to withstand a seismic action having a larger probability of occurrence than the No-collapse design seismic action, without the occurrence of damage and the associated limitations of use, the costs of which would be disproportionately high in comparison with the costs of the structure itself.

b) Damage limitation requirement

For the seismic action in Damage limitation requirement, the probability of exceedance ( ) in 50 years is 10% and the return period (

2.3.4.2 Design Peak Ground Acceleration

) is 475 years.

The design peak ground acceleration at the ultimate limit state - No-collapse requirement - shall correspond to a design ground acceleration coefficient for a 2,450 year return period event as follows:

, Return Period 2,450 year

The design peak ground acceleration at the serviceability limit state - Damage limitation requirement - shall correspond to a design ground acceleration coefficient for a 475 year return period event as follows:

= 0.088g

, Return Period 475 year

2.3.4.3 Ground Type

= 0.052g

Considering the soft deep clay in the Brunei Bay, the ground type should be identified in accordance with Table 3.1 of BS EN 1998-1.

The Contractor should assess the ground condition at each foundation location and identify the ground type for the foundation design.

2.3.4.4 Design Response Spectra - Horizontal motion

The design response spectra for the bridge shall be in accordance with BS EN 1998-1 and BS EN 1998-2. The design seismic action should be calculated by a response spectrum of Type 2.

For the horizontal components of the seismic action, the design spectrum, )(TSd , can be

defined by the following expressions:

−⋅+⋅⋅=≤≤

325.2

32)(:0

qTTSaTSTT

BgdB

q

SaTSTTT gdCB5.2)(: ⋅⋅=≤≤

gC

gdDC aTT

qSaTSTTT ⋅≥

⋅⋅⋅=≤≤ β5.2)(:

gDC

gdD aTTT

qSaTSTT ⋅≥

⋅⋅⋅=≤ β2

5.2)(:




Where T is the structural period, q is the behavior factor, β is the lower bound factor for the horizontal design spectrum.

According to Clause 6.5.2 of BS EN 1998-2, non-ductile components such as bearings, anchorage zone or non-ductile connections shall be designed neglecting ductile behavior, i.e., q=1.0. Besides of non-ductile components, the design spectrum considering ductile behavior shall be applied to the seismic design, i.e., q=1.5.

For this Project, the behaviour factors (q) shall be taken as follows:

Ultimate Limit State : q = 1.5 for the elements with ductile behavior

q = 1.0 for the other elements

Serviceability Limit State : q = 1.0

2.3.4.5 Design Response Spectra - Vertical Motion

Design response spectra for vertical motion should be taken as 60% of the horizontal motion in accordance with Clause 3.2.2.3 of BS EN 1998-1.

2.3.4.6 Damping Correction Factor

In accordance with BS EN 1998-1, the response spectrum shall be modified by the damping correction factor, η , to allow for levels of dampening other than 5%.

55.0)5/(10 ≥+= ξη

where ξ is the viscous damping level ratio of the structure as a percentage.

2.3.4.7 Seismic Analysis and Design

The CQC (Complete Quadratic Combination) modal combination method shall be used for combination of the effects from different modes.

The combination rules for the directional seismic loads are as follows:

zyx EQEQEQ 3.03.00.1 ++

zyx EQEQEQ 3.00.13.0 ++

zyx EQEQEQ 0.13.03.0 ++

2.4 Accidental Loads

2.4.1 Vessel Collision The ship impact loads from possible vessel collision shall be determined in accordance with the requirements of the AASHTO "Guide Specification and Commentary for Vessel Collision Design of Highway Bridges (1991)". The Contractor shall prove that the annual collapse frequency (AF) of the PMB Bridge is less than 0.0001 and verify the design loads specified in these design criteria using the Method II risk analysis procedures for a 'Critical' bridge classification.

2.4.1.1 Impact Load on Substructure

The estimation of the impact load on piers during a ship collision is a very complex problem. The actual force is time dependent, and varies depending on the type, size and construction of the vessel. Therefore, impact load on substructure should be carefully determined to refer to the below Volume III-1 Investigation/Study Documents:




- Appendix 3F MARINE AND NAVIGATIONAL STUDY

- Appendix 3I RECORDS OF DISCUSSIONS BETWEEN ENGINEER AND EMPLOYER AND AUTHORITES

2.4.1.2 Impact Load on Superstructure

The superstructure of the PMB Bridge should be designed to sustain an equivalent static force in any longitudinal direction if higher forces are not to be expected.

The design vessel collision loads on superstructures shall be taken as 1 MN in accordance with Clause 4.6.2 of BS EN 1991-1-7.

2.4.2 Collision with Vehicle Restrain Systems For the vehicle restraint systems, horizontal and vertical forces transferred to the bridge deck by vehicle restraint systems from vehicle collision should be taken into account in accordance with Clause 4.7.3 of BS EN 1992-2.

2.5 Actions on Structures Exposed to Fire The action of fire on the structure shall be checked in accordance with BS EN 1991-1-2.

As a minimum, the following fire scenarios shall be assessed:

a) A fuel fire from a ship under the bridge

b) A vehicle on fire on the carriageway

2.6 Actions during Execution Actions during execution shall be calculated in accordance with BS EN 1991-1-6.

It is the Contractor's responsibility to propose a construction method and sequence, to design the temporary and permanent works and to verify the adequacy of the permanent works during construction.

Where structures are subject to construction equipment essential to the proposed construction method, the structures shall be checked for construction loads at each construction stage and the assumed loads shall be indicated on the drawings.

When verifying the safety of the structure, the Contractor shall use dynamic amplification factors appropriate to the proposed construction methods. A minimum dynamic amplification factor shall be not less than 1.2 on the loads lifted during normal lifting operations.




3 LOAD COMBINATIONS

For the design of the PMB Bridge, appropriate load combinations have been selected according to BS EN 1990:2002. With the identified loading effects, two limit state conditions shall be verified with the partial factor method. Particularly, it shall be verified that the design load effects do not exceed:

- the design resistance of structure in Ultimate Limit State (ULS)

- the relevant criteria for Serviceability Limit State (SLS)

The Contractor shall establish reasonable load combinations in accordance with BS EN 1990.

3.1 Ultimate Limit State The following ultimate limit states shall be verified as relevant:

1) persistent and transient design situations

a) EQU : Loss of static equilibrium of the structure

b) STR : Internal failure or excessive deformation of the structure

c) GEO : Failure or excessive deformation of the ground

d) FAT : Fatigue failure of the structure or structure members

2) accidental and seismic design situations

a) accidental design situations (ACC) : impact or consequences of localized failure

b) seismic deign situations (SEIS)

3.1.1 Load Combination Rules The design values of actions shall be in accordance with Table A2.4(A) to (C) of BS EN 1990 Annex A2.

Table IV-3.1 Load Combination Rules for EQU and STR/GEO

Combination Permanent actions

Prestress Leading variable action

Accompanying variable actions

Unfavourable Favourable Main (if any) Others

Combination rule for EQU (Set-A)

(Eq. 6.10) sup,sup, kjGj Gγ inf,inf, kjGj Gγ Ppγ 1,1, kQ Qγ - ikiiQ Q ,,0,ψγ

Combination rule for STR/GEO (Set-B)

(Eq. 6.10a) sup,sup, kjGj Gγ inf,inf, kjGj Gγ Ppγ 1,1,01, kQ Qψγ ikiiQ Q ,,0,ψγ

(Eq. 6.10b) sup,sup, kjGj Gξγ inf,inf, kjGj Gγ Ppγ 1,1, kQ Qγ ikiiQ Q ,,0,ψγ

85.0=ξ so that 15.135.185.0sup, ≅×=Gξγ

Combination rule for STR/GEO (Set-C)

(Eq. 6.10) sup,sup, kjGj Gγ inf,inf, kjGj Gγ Ppγ 1,1, kQ Qγ ikiiQ Q ,,0,ψγ




Table IV-3.2 Load Combination Rules for ACC & SEIS


Prestress Accidental or seismic action

Accompanying variable actions

Unfavourable Favourable Main

(if any) Others

Accidental (Eq. 6.11a/b) sup,kjG inf,kjG P dA

1,1,1 kQψ

or

1,1,2 kQψ ikiQ ,,2ψ

Seismic (Eq. 6.11a/b) sup,kjG inf,kjG P EkEd AA 1γ= ikiQ ,,2ψ

3.1.2 Combination Factor Values of ψ factors shall be taken in accordance with Annex A2 of BS EN 1990.

Table IV-3.3 Combination factor

Action Symbol 0ψ 1ψ 2ψ

Road traffic (L)

gr1a

TS 0.75 0.75 0

UDL 0.4 0.4 0

Footway 0.4 0.4 0

gr1b Single axle 0 0.75 0

gr2 Horizontal forces 0 0 0

Wind W 0.6 0.2 0

Thermal T 0.6 0.6 0.5

WA ) 0.6 0.2 0

1) Since waves generally come with winds, the combination factor for the design wave load is the same as that of wind load.




3.1.3 Partial Load Factor

Values of partial load factors( Gγ , Qγ ) shall be taken in accordance with Annex A2 of BS EN

1990.

Table IV-3.4 Partial load factors

Action

EQU (Set-A) STR/GEO (Set-B) STR/GEO

(Set-C) ACC/SEIS

Eq.6.10 Eq.6.10a Eq.6.10b Eq.6.10 Eq.6.11a/b

Dead load (DC, DW, CS) 1.05 (0.95)

1.35 (1.00)

1.35 (1.00) 1.00 1.00

Settlement (SD) 1.05 (0.00)

1.35 (0.00)

1.35 (0.00)

1.00 (0.00)

1.00 (0.00)

Prestressing force (PS) 1.00 1.00 1.00 1.00 1.00

Road Traffic (L) 1.35 1.35 1.35 1.15 1.00

Wave (WA) 1.50 1.50 1.50 1.30 1.00

Wind (W) 1.50 1.50 1.50 1.30 1.00

Temperature (T) 1.50 1.50 1.50 1.30 1.00

Ship Collision (SC) 0.00 0.00 0.00 0.00 1.00

1) The values in parentheses refer to the values where unfavourable. 2) In cases where the effects of variable loads are favourable, the load effects shall not be taken into account.




3.1.4 Design Load Combinations

The design load combinations in accordance with BS EN 1990 are presented below.

Table IV-3.5 Design load combinations of ULS-EQU (Set-A)

No. Leading Action

Permanent Loads, G Variable Loads, Q

DC,DW SD,CS

PS Road traffic (L)

Wind (W)

Wave (WA)

Temp. (T)

Unfav. Fav. TS UDL Single axle

Horizon -tal

1 L-gr1a 1.05 0.95 1.0 1.35 1.35 - - 0.9 0.9 0.9

2 L-gr1b 1.05 0.95 1.0 - - 1.35 - - - -

3 L-gr2 1.05 0.95 1.0 1.01 0.54 - 1.35 0.9 0.9 0.9

4 Wind 1.05 0.95 1.0 1.01 0.54 - - 1.5 0.9 0.9

5 Wave 1.05 0.95 1.0 1.01 0.54 - - 0.9 1.5 0.9

6 Temp 1.05 0.95 1.0 1.01 0.54 - - 0.9 0.9 1.5

Table IV-3.6 Design load combinations of ULS-STR/GEO (Set-B)

No. Leading Action


DC,DW SD,CS

PS Road traffic (L)

Wind (W)

Wave (WA)

Temp. (T)


Horizon -tal

1 - 1.35 1.0 1.0 1.01 0.54 - - 0.9 0.9 0.9

2 L-gr1a 1.15 1.0 1.0 1.35 1.35 - - 0.9 0.9 0.9

3 L-gr1b 1.15 1.0 1.0 - - 1.35 - - - -

4 L-gr2 1.15 1.0 1.0 1.01 0.54 - 1.35 0.9 0.9 0.9

5 Wind 1.15 1.0 1.0 1.01 0.54 - - 1.5 0.9 0.9

6 Wave 1.15 1.0 1.0 1.01 0.54 - - 0.9 1.5 0.9

7 Temp 1.15 1.0 1.0 1.01 0.54 - - 0.9 0.9 1.5




Table IV-3.7 Design load combinations of ULS-STR/GEO (Set-C)

No. Leading Action


DC,DW SD,CS

PS Road traffic (L)

Wind (W)

Wave (WA)

Temp. (T)


Horizon -tal

1 L-gr1a 1.0 1.0 1.0 1.15 1.15 - - 0.78 0.78 0.78

2 L-gr1b 1.0 1.0 1.0 - - 1.15 - - - -

3 L-gr2 1.0 1.0 1.0 0.86 0.46 - 1.15 0.78 0.78 0.78

4 Wind 1.0 1.0 1.0 0.86 0.46 - - 1.3 0.78 0.78

5 Wave 1.0 1.0 1.0 0.86 0.46 - - 0.78 1.3 0.78

6 Temp 1.0 1.0 1.0 0.86 0.46 - - 0.78 0.78 1.3

Table IV-3.8 Design load combinations of ULS-ACC

No. Main

Variable Action

Permanent Loads, G Accidental Loads Variable Loads, Q

DC,DW SD,CS

PS Ship Collision

SC Road traffic (L)

Wind (W)

Wave (WA)

Temp. (T)

Unfav. Fav. TS UDL

1 L-gr1a 1.0 1.0 1.0 1.0 0.75 0.4 - - 0.5

2 Wind 1.0 1.0 1.0 1.0 - - 0.2 - 0.5

3 Wave 1.0 1.0 1.0 1.0 - - - 0.2 0.5

4 Temp 1.0 1.0 1.0 1.0 - - - - 0.6

Table IV-3.9 Design load combinations of ULS-SEIS

No. Leading Action

Permanent Loads, G

Seismic Load

Variable Loads, Q

DC,DW SD,CS

PS Road traffic (L)

Wind (W)

Wave (WA)

Temp. (T)

Unfav. Fav. TS UDL

1 - 1.0 1.0 1.0 1.0 - - - - 0.5




3.2 Serviceability Limit State The verification of serviceability limit states should be based on criteria concerning the following aspects:

a) deformations that affect

- the appearance,

- the comport of users, or

- the functioning of the structure

or that cause damage to finishes or non-structural members ;

b) vibrations

- that cause discomfort to people, or

- that limit the functional effectiveness of the structure ;

c) damage that is likely to adversely affect

- the appearance,

- the durability, or

- the functioning of the structure.

The combinations of actions for serviceability limit state are defined as follows:

a) Characteristic combination (CLC) : irreversible limit state

b) Frequent combinations (FLC) : reversible limit state

c) Quasi-permanent combination (QLC) : long-term effects and the appearance

of the structure

3.2.1 Load Combination Rule For the above-mentioned limit states such as Characteristic, Frequent and Quasi-permanent combinations, the design values of actions shall be in accordance with Table A2.6 of BS EN 1990 Annex A2.

Table IV-3.10 Design values of actions for serviceability limit state


Prestress Variable actions

Unfavourable Favourable Main

(if any) Others

Characteristic sup,kjG inf,kjG P 1,kQ ikiQ ,,0ψ

Frequent sup,kjG inf,kjG P 1,1,1 kQψ ikiQ ,,2ψ

Quasi-permanent sup,kjG inf,kjG P 1,1,2 kQψ ikiQ ,,2ψ

3.2.2 Combination Factor The combination factors for the serviceability limit state are the same as that of ultimate limit state.




3.2.3 Design Load Combinations The design load combinations in accordance with BS EN 1990 are presented below.

Table IV-3.11 Design load combinations of Characteristic combination (SLS-CLC)

No. Leading Action


DC,DW SD,CS

Prestress Road traffic (L)

Wind Wave (WA)

Temp. (T)

Unfav. Fav. TS UDL Single axle Horizontal

1 L-gr1a 1.0 1.0 1.0 1.0 1.0 - - 0.6 0.6 0.6

2 L-gr1b 1.0 1.0 1.0 - - 1.0 - - - -

3 L-gr2 1.0 1.0 1.0 0.75 0.4 - 1.0 0.6 0.6 0.6

4 Wind 1.0 1.0 1.0 0.75 0.4 - - 1.0 0.6 0.6

5 Wave 1.0 1.0 1.0 0.75 0.4 - - 0.6 1.0 0.6

6 Temp 1.0 1.0 1.0 0.75 0.4 - - 0.6 0.6 1.0

Table IV-3.12 Design load combinations of Frequent combination (SLS-FLC)

No. Leading Action


DC,DW SD,CS

PS Road traffic (L)

Wind (W)

Wave (WA)

Temp. (T)


1 L-gr1a 1.0 1.0 1.0 0.75 0.4 - - - - 0.5

2 L-gr1b 1.0 1.0 1.0 - - 0.75 - - - -

3 Wind 1.0 1.0 1.0 - - - - 0.2 - 0.5

4 Wave 1.0 1.0 1.0 - - - - - 0.2 0.5

5 Temp 1.0 1.0 1.0 - - - - - - 0.6

Table IV-3.13 Design load combinations of Quasi-permanent combination (SLS-QLC)

No. Leading Action


DC,DW SD,CS

PS Road traffic (L)

Wind (W)

Wave (WA)

Temp. (T)


1 - 1.0 1.0 1.0 - - - - - - 0.5




3.2.4 Serviceability Performance Requirement In addition to that required by the Eurocodes, the following requirements are to be considered on this structure:

a) The functioning of the structure or structural member under normal use.

b) Road safety in terms of rapid changes in road gradient and super elevation.

c) Excessive ponding of surface water.

d) The comfort of road users in terms of oscillations and wind speeds.

e) The appearance of the works in terms of deflections, twists and concrete cracking.

These conditions are deemed to be satisfied if the structure complies with the relevant Eurocode and the following requirements.

3.2.4.1 Camber

The superstructure shall be cambered to compensate deflections from dead load, creep and shrinkage. The theoretical correct alignment shall be achieved after 25 years of creep and shrinkage effects.

3.2.4.2 Deformation

The Contractor shall propose suitable criteria for deformations including but not limited to deflection of navigation span, twist of deck, relative movement and rotation at expansion joints. The criteria for deformations shall be reviewed by the Engineer.

Especially, for the main bridge, the following serviceability performance requirements should be secured:

1) Allowable vertical deflection under variable loads : L/200 (L : span length, m)

2) Deck acceleration under wind speed of 25m/s : 0.2m/

3.3 Fatigue Verification Over the lifespan of a bridge, constant road traffic moving over the bridge will produce a large number of repetitive loading cycles in the steel components. Such components can become susceptible to fatigue damage. As a consequence, fatigue assessment shall be carried out for all steel structures in accordance with BS EN 1993-1-9 and BS EN 1993-2.

The Contractor shall verify that the fatigue life exceeds the design life of the structure through the appropriate assessment such as unlimited life method and damage accumulation method, etc.




4 DESIGN OF STRUCTURAL ELEMENTS

4.1 Structural Analysis Load effects due to actions shall be calculated by appropriate structural analyses. Any analysis shall comply with the relevant section of the Eurocode.

The assumed stiffness of structural elements shall be appropriate to the expected behaviour anticipated. Geometrically non-linear analyses shall be carried out where the effects of non-linearity are significant.

4.2 Steel Structures Steel structures shall be designed in accordance with EN 1993-2. Design of steel structure with thin plates shall be taken into account the effect of local instability that reduces the ultimate resistance.

4.2.1 Partial Safety Factors

The partial safety factors ( 0Mγ , 1Mγ ) for steel structures are as follows:

Resistance of cross section to yielding and local buckling : 1.0

Resistance of members to instability : 1.1

Resistance of joints and cross section in tension to fracture : 1.25

Slip resistance : 1.25

4.2.2 Material Properties Material properties of steel structure shall be in compliance with BS EN 1993-1-1, BS EN 10025-3 and relevant European Standards. All material and components shall be ordered from and produced by manufactures and supplies with proven and documented experience of producing material to the codes and standards required.

4.3 Concrete Structures The design of concrete structures shall be in accordance with BS EN 1992-2.

4.3.1 Partial Safety Factors Partial factors shall be taken in accordance with BS EN 1992-2. The values for the Employer's Concept Design are as follows:

Table IV-4.1 Partial factors for concrete structure

Limit state Design situation

Partial factor, γ

Concrete Reinforcing steel Prestressing steel

ULS Persistent & Transient 1.5 1.15 1.15

ULS Accidental 1.2 1.0 1.0

SLS Persistent & Transient 1.0 1.0 1.0




4.3.2 Material Properties

4.3.2.1 Concrete

Material properties of concrete structure shall be in compliance with BS EN 1992-1-1, EN 206-1 and relevant European Standards.

The values of the design compressive and tensile strengths are defined as follows:

Design compressive strength : cckcckcccd fff γγα /85.0/ ×==

Design tensile strength : cctkcctkctctd fff γγα /0.1/ 05.0,05.0, ×==

4.3.2.2 Steel Reinforcement

Steel reinforcement shall be in accordance with BS EN 1992-1-1, and comply with EN 10080.

Ductility class of steel reinforcement shall be taken as Class C.

The elastic modulus of reinforcement shall be not less than Es = 200GPa.

4.3.2.3 Prestressing Strand

Prestressing strands shall be low-relaxation strands in accordance with BS EN 1992-1-1 and EN 10138-3. The minimum tensile strength shall be taken as 1860MPa.

4.3.2.4 Prestressing Bar

Prestressing bars shall be in accordance with BS EN 1992-1-1 and EN 10138-4.

4.3.3 Stress Limit Longitudinal cracks may occur if the stress level exceeds a critical value. Such cracking may lead a reduction of durability. For this project, the following stress limits can be used.

Characteristic combination : ckf6.0

Quasi-permanent combination : ckf45.0

In the calculation of stresses and deflections, uncracked cross-sections can be used provided that the flexural tensile stress does not exceed ctmf .

4.3.4 Exposure Class and Nominal Cover Exposure conditions are chemical and physical conditions to which the structure is exposed in addition to the mechanical actions.

According to clause 4.2 of BS EN 1992-1-1 and EN 206-1, exposure classes for the Employer's Concept Design are provided in below table.

Table IV-4.2 Exposure classes of the concrete elements (indicative only)

Exposure Class

Environment Condition Structures Exposure Condition

XC3 Corrosion induced by carbonation Inner faces of structures Surfaces inside structures with moderate or

high air humidity

XS1

Corrosion induced by chlorides from

sea water

Exterior of structures over EL.+5.0m

Exposed to airborne salt but not in direct contact with sea water

XS2 Exterior of structures up to EL.+0.0m Permanently submerged in sea water

XS3 Exterior of structures

from EL.+0.0m up to EL.+5.0m

Structures in tidal, splash and spray zone




The Contractor shall verify the above exposure classes, provide the criteria appropriate for his design and calculate a required concrete cover to secure a 100 year service life in accordance with Clause 4.4.1 of BS 1992-1-1 and EN 206-1.

4.3.5 Crack Width The concrete structure shall be checked for crack width in accordance with BS EN 1992-2.

4.4 Foundation

4.4.1 General The foundation shall be designed in accordance with BS EN 1990 and BS EN 1997-1~2. The design shall ensure sufficient bearing capacity and stiffness of the foundations.

Where soil-structure interaction analyses are carried out for ultimate limit state verification, the design values of soil stiffness shall be consistent with the design values of soil strength.

The foundations for the bridge shall be designed to achieve compatibility of load and deflection between the bridge deck and associated substructure.

4.4.2 Partial Load Factor The partial factors on actions or the effects of actions for the Ultimate Limit State - STR and GEO - shall be applied as follows:

1) Combination 1 : A1 + M1 + R1

Permanent loads : 1.35 (Unfavourable) / 1.00 (Favourable)

Variable loads : 1.50 (Unfavourable) / 0.00 (Favourable)


Permanent loads : 1.00 (Unfavourable) / 1.00 (Favourable)

Variable loads : 1.30 (Unfavourable) / 0.00 (Favourable)

4.4.3 Partial Safety Factor

4.4.3.1 Bored Piles

The values of partial safety factors for bored piles shall be as follows:


Base Resistance, bγ : 1.25

Shaft (compression), sγ : 1.0

Total/combined (compression), tγ : 1.15

Shaft in tension, ts,γ : 1.25









4.4.3.2 Driven Piles

The values of partial safety factors for driven piles shall be as follows:











4.4.4 Scour Scour design shall be for the current and wave conditions and return period of 100 years.

The design of scour protection at the foundations and the determination of predicted scour depths, if any of the foundation designs incorporate an allowance for scour, shall be verified by physical model tests in combination with numerical modelling. Numerical models shall be used to assess the general behaviour of the flows and the boundary conditions for physical models, and the physical models used to assess the detailed scour behaviour.

4.5 Aerodynamic Stability The adequacy of the structure to withstand the dynamic effects of wind, together with other coincident loadings, shall be verified in accordance with the appropriate parts of Eurocode.

4.6 Miscellaneous

4.6.1 Bearings Bearings shall be capable of transferring loads between the superstructure and substructure due to permanent loads and variable loads such as traffic, wind, temperature, etc.

The design of bearing shall be in accordance with BS EN 1337-Bridge Bearings and Annex A of BS EN 1993-2 where appropriate.

The type of bearing shall be suitable for the hot weather conditions in Brunei.

Bearings shall be designed to allow the inspection, maintenance, removal and replacement without any modification to the permanent structure and the need to close the bridge under normal traffic.

4.6.2 Expansion Joints




Expansion joint shall be capable of sustaining traffic loading and accommodating movements from traffic, wind, temperature, settlement, creep and shrinkage, etc.

The type of expansion joint and the design loads and movements shall be determined in accordance with the requirements of Annex B of BS EN 1993-2. In addition, the expansion joint shall be designed such that it does not close completely for infrequent design situations at the SLS and that the full design opening shall be less or equal to the guaranteed capacity of the joint. The movement joints shall be capable of accommodating the vertical traffic design loads when fully open under ULS design situations. Also, the hot weather conditions in Brunei shall be considered.

4.6.3 Drainage The drainage design for bridge deck shall be based on 50 year or greater return period storm.

The drainage system shall be provided to dispose of water collected within the area of the bridge structure.

Direct discharge from the deck into the Brunei Bay shall only be permitted where the bridge deck is located directly above water. The Contractor shall consult and comply with the requirements of all necessary authorities in this regard and in respect of pollution protection provision and include measures as necessary.

The drainage from the zones over inter-tidal areas shall be taken back to the abutments for connection to the adjoining road drainage system.

4.7 Special Consideration

4.7.1 Durability

4.7.1.1 General

All structural elements of the PMB Bridge shall have sufficient durability to achieve a design working life of 100 years in accordance with BS EN 1990, taking into consideration the environmental exposure class and a consequence class CC2 in accordance with Annex B of BS EN 1990. The Contractor shall identify the appropriate exposure class for each element in order to ensure the required durability of all structural elements and replaceable components.

4.7.1.2 Concrete Element

The structural concrete of the PMB Bridge shall comprise of a high strength, high performance concrete that shall provide adequate performance in accordance with the contract requirements.

The Contractor shall demonstrate the performance of the concrete to provide a suitable level of protection to the embedded reinforcement against chloride-induced corrosion over the whole of the design working life. Chloride ion content profiles together with an analysis of the chemical composition of the samples of concrete may be used to aid in characterisation of the environmental exposure condition.

This demonstration shall include identification of the required maximum chloride diffusion coefficient necessary to ensure the threshold chloride level for corrosion initiation is not achieved at the position of the reinforcement within the design working life. The demonstration shall include the results of chloride diffusion tests in accordance with the specification to demonstrate compliance with the contract requirements.




The Contractor shall develop suitable concrete mix designs and safe curing methods to ensure that any cracking due to early thermal effects does not exceed appropriate permissible crack widths specified in BS EN 1992-2.

4.7.1.3 Steel Element

It shall be assumed that all inaccessible, enclosed steel voids can suck in moist air through porous welds, and hence water be accumulated within such voids. Either of the following two methods shall be used to compensate for this problem:

All low points in voids shall be provided with a small drain hoe, 40mm minimum diameter, and all surfaces shall be provided with an appropriate sacrificial thickness of additional steel which is deemed to be non-structural.

Voids shall be sealed and linked together so as to conduct dehumidified air to every internal steel surface.

As for steel piles embedded in the ground, the allowance for loss of thicknesses due to corrosion shall be in accordance with 4.2 of BS EN 1993-5. Painting of permanent steel piles shall not be taken into account as part of sacrificial corrosion protection layer.

4.7.2 Maintenance and Inspection

4.7.2.1 General

A design life of 100 years will be guaranteed by regular inspection and maintenance work for the main structure elements, which would lead to the best performance during the operation period. Detailed inspection and maintenance are inevitable in order to maintain the function of the bridge members since the bridge is exposed to a severe marine environment such as corrosion by chloride. Therefore, it is required to perform periodic inspection.

The Contractor shall make the provisions for maintenance and inspection of the bridge elements and propose access plan.

The shape and details of the bridge and access systems shall be such that the condition of all components can be assessed for their condition and reliability within the lifetime of the structure. The accesses shall be designed at suitable locations to perform the maintenance or inspection activities without any interruption to the normal traffic flow.

For the safe usage and effective maintenance of the bridge, the Contractor shall propose the maintenance and inspection strategy in the design including but not limited to:

Plan for sustainability such as the protective paint system, dehumidification facilities and so on is applied in order to reduce the maintenance;

Periodic and scheduled inspection for all the elements shall be carried out in accordance with the maintenance manual;

Access facilities such as inspection gantry, hand rail and so on shall be properly installed for easy maintenance and inspection.

4.7.2.2 Location-Specific Inspection and Maintenance Access

The Contractor shall provide a detailed elaboration of his specification proposals for the provision of maintenance and inspection access at the following locations and at any other locations on the proposed bridge which may be necessary for the achievement of a complete and thorough bridge inspection and maintenance inspection access system. In producing the detailed specification proposals, the Contractor shall extract and incorporate all relevant Brunei Standards and/or British Standards.

The provision of maintenance and inspection access shall include but not limited to:

Bridge deck;




Pier; Foundation; Expansion joints and bearings, etc.

4.7.3 Electrical System including Lighting The Contractor shall design and provide the electrical power supply system for all equipment and systems of the PMB Bridge and Road. The electrical systems shall comprise but not be limited to the following:

Incoming power supply from the power supplier; Provision of normal power supply installation including distribution boards, circuit

breakers, protection/measurement relays etc; Main and sub-main distribution system for all electrified equipment; Lighting systems and the associated control equipment including interior lighting, road

lighting, architectural lighting at night, aircraft and marine warning lights and the necessary power supply accessories for the other lighting systems;

Lightning protection system.

The electrical systems shall be designed and provided based on the following local codes and international standards:

Brunei Standards; European Standards; European Union Directives; BS 7671 2008: Requirements for Electrical Installation; UK Chartered Institution of Building Services Engineers - Guides and Publications.




PART Ⅴ. UTILITY DESIGN




PART Ⅴ. UTILITY DESIGN

1 WATER SUPPLY

1.1 Introduction The design criteria guidelines adopted are those widely used in Brunei and recommended by Design manual for water supply distribution networks (Government of Negara Brunei Darussalam, 1990)

1.2 Treated Water Supply Design

1.2.1 The Purpose for Treated Water Supply

The purpose of the treated water scope shall be to provide consistent and continuous conveyance of treated water supply from mainland to PMB in accordance with the Employer’s Requirements in all weather and climatic conditions.

1.2.2 Tapping Point Water pressure at the tapping point connecting to the existing national grid is 2.5 bar.

1.2.3 Pumping Station The pumping station for treated water shall be composed of the pumping system with water tank in order to provide the stable water supply.

1.2.4 Elevated Water Tank in PMB The low water level in the elevated water tank shall be remained at least of (+) 24m.

1.3 Untreated/Raw Water Supply Design

1.3.1 The Purpose of Untreated/Raw Water Supply The purpose of the Untreated/Raw water scope shall be to provide consistent and continuous conveyance of Untreated/Raw water supply from mainland to PMB in accordance with the Employer’s Requirements in all weather and climatic conditions.

1.3.2 Untreated/Raw Water Source and Amount The untreated/raw water is provided at the Serasa Sewerage Treatment Plant (Serasa STP) in the Mainland.

1.4 Design criteria

1.4.1 Roughness Coefficient The roughness coefficient of Ductile iron pipe shall be as follows:

Condition : 20 years old




Coefficient : 90

1.4.2 Pipeline Pressure The system should be designed to ensure every customer receives a minimum head of 17m. The maximum head at any service should be limited to 100m.

1.4.3 Pipeline Velocity Typically flow velocities for water supply pipe mains stay in the range between 0.3m/sec to 1.2m/sec.

1.4.4 Sluice Valves Sluice valves are generally installed as follows:

Three at crosses

Two at tees

One on single hydrant branches

Generally on cross country pipelines, sluice valves should be installed every 1 to 2kms.

1.4.5 Washout Valves Washout valves should be provided at selected points in the system where drainage is available for the disposal of the water.

1.4.6 Air Valves General guide to the sitting of air valves in water pipeline, the following guidelines for the placement of air valves are given:

after a pump discharge valve – fit a double orifice air valve

where a peak in pipeline occurs – fit a double orifice air valve

where pipeline is parallel to hydraulic gradient – fit double orifice air valve at each end of section with either double orifice air valve or single small orifice air valves at suitable intervals (i.e. every 600m to 700m) along the pipeline.

on long horizontal sections without a peak – vent at suitable regular intervals (i.e. 600m to 700m) along the pipeline using single orifice air valves

where any substantial change in downward slope occurs – fit a single orifice air valve

1.4.7 Depth of Cover The minimum cover of water pipeline should be as follows:

750mm under crown of road

600mm in verge

1.4.8 Thrust Blocks In pipelines with flexible joints a means of resisting unbalanced forces at bends, tees, branch pipes and blank ends shall be provided.

1.4.9 Pumping Capacity The duty pumps of pumping stations shall be capable of pumping within 20 hours. The capacity of standby units shall not be less than 25% of the capacity of duty pumps or not less than the capacity of the largest unit whichever is the greater.




1.4.10 Class of pipe In all cases, the class of pipe, fitting or valve selected shall be capable of withstanding a maximum test pressure equal to 135m, or 1.5times the working pressure, or the maximum surge pressure, whichever is the greatest.




2 POWER

2.1 The Purpose of Power Supply The purpose of the power supply scope shall be to provide consistent and continuous conveyance of power supply from mainland to PMB in accordance with the Employer’s Requirements in all weather and climatic conditions.

2.2 Power Supply Source The power supply for PMB will be obtained from an existing 11kV Main Intake Station RTB Station Muara located at Simpang 276, Jalan Serasa. The power supply cables will be laid underground from this sub-station along Simpang 276, along Jalan Serasa, along the road linking Jalan Serasa and Jalan Perusahaan, along Jalan Perusahaan and along the west approach road. The cables will then run in ducts under the PMB Bridge and then will be laid underground along the east approach road and terminated at a new sub-station in PMB.

2.3 Cabling The HV cables will be cross linked polyethylene insulated cables (XPLE) run underground from the existing sub-station to the new PMB Bridge and from the PMB Bridge to the new sub-station in PMB. The cables will be laid underground as they take up less right-of-way than overhead lines and are less affected by bad weather.

2.4 PMB Sub-Station The 11kV distribution sub-station will be located central to the distribution areas to be served in PMB. The sub-station will require sufficient land area for the installation of equipments with the necessary clearance for electrical safety and maintenance access of the large apparatuses such as transformers. The sub-station site shall have room for expansion due to load increase or planned additions.

Consideration shall be given to address the environmental effects such as drainage, oil spillage from the oil immersed transformer, noise and road traffic effects for maintenance access.

The sub-station will have a combination of switching, controlling and voltage step-down arranged to reduce the 11kV transmission voltage to 415V primary distribution voltage. The level of security of supply determines the layout of the substation. The arrangement of switches, circuit breakers and buses will affect cost and reliability of the substation. Ideally, the substation with all circuits and equipments duplicated will provide the highest level of security of supply where a connection remains available following a fault or during maintenance, but this is costly.

For PMB, it is proposed that the new sub-station will have a ring bus arrangement so that failure of any circuit breaker will not interrupted power to other circuits and so that parts of the sub-station may de-enrgised for maintenance and repairs without interruption of service to other circuits. This ring bus arrangement is economical design, high reliability and adaptable for future expansion to the breaker-and-a-half arrangement.

2.5 Low Voltage (LV) Distribution The power for the PMB areas will distributed from the new PMB sub-station. Power for the PMB Bridge and Road will also be supplied form the new PMB sub-station.




3 TELECOMMUNICATION

3.1 The Purpose of Telecommunication Service The purpose of the telecom service scope shall be to provide consistent and continuous conveyance of telecommunication from mainland to PMB in accordance with the Employer’s Requirements in all weather and climatic conditions

3.2 Connection Points Connection points for PMB telephone lines requirements will be from an existing telephone exchange building at the main Muara Road, located opposite Setia Ali Mosque, approximately 2km from Serasa where the new PMB Bridge is to be located.

3.3 Cabling Fibre optic cables will be laid from this telephone exchange to PMB. The fibre optic cables will be laid underground from telephone exchange along Jalan Muara across to Jalan Perusahaan, along Jalan Perusahaan and along the new road. The cables will then run in ducts under the new bridge and then will be laid underground along the new PMB Road and terminate at a new external ODF (Optical Distribution Frame) in PMB.

3.4 Distribution From the new PMB telephone exchange, fibre optic cables will run underground to the various users in PMB.

design criteria

Documents

general requirements

general design requirements

functional requirements

durability requirements

aesthetical requirements

environmental requirements

coordinate system

weighing system