construction of the superstructure of major sea...

Matt Carter | Associate Director

2nd International Seminar on Design & Construction of Second Penang Bridge

Construction of the Superstructure of Major Sea Crossings

2 Second Penang Bridge

3 Typical Sea Crossing Bridges

Donghai Bridge Incheon Bridge

Penang Bridge Shenzhen Western Corridor

4 Long Section

Scale H:V = 10:1

Maximum water depth = 10m

Typical water depth = 2 to 3m

5 Stonecutters Bridge, Hong Kong

6 Second Penang Bridge, Malaysia

7 Substructure optimization

Substructure is typically around one third of the total cost

Innovative design gives substantial savings

Depends on ground conditions

Innovations: - Construction methods

- Lateral pile load tests

- Articulation

- Seismic isolation

Typical Superstructure

9

Quality – Production line casting in a controlled environment

Economy – Repetitive operations, re-use of equipment

Safety – Minimise working at height and over water

Advantages of precast construction

10

Quality Cost Speed of

Construction Durability Safety

Environmental Impact

Aesthetics

Design Drivers

11

Quality Cost Speed of Construction

Durability Safety Environmental

Impact Aesthetics

Design Drivers

12

For given site conditions there will be an optimum economic span

With current technologies in shallow seas without navigation requirements this is typically around 50m to 55m

Span

Cost

Low elevation / shallow water

High elevation / deep water

Economic Comparison of First Penang Bridge

Based on prevailing costs and available technologies in July 1977

Source: The Penang Bridge, Planning Design and Construction by Tan Sri Datuk Professor Ir. Chin Fung Kee

14

Asia’s first precast segmental bridge

Design & Build contract

Opened 1991

Kwun Tong Bypass Phase 2

Balanced cantilever segment erection

Completed project next to the old Kai Tak Airport Overhead gantry weighted 400 tonnes and was 130m long

15

Comparison between First and Second Penang

Penang Bridge (1985) 40m PC beam and slab

Second Penang Bridge (2013) 55m precast segmental box girders

Typical Cross Section

16m is enough for a three lane highway with full width breakdown land

Typically 10 – 16m Typically 10 – 16m

Precast Segmental Span by Span

19 Span by Span Erection

20

Erection Sequence

21 Erection Gantry

22

23

24 Srtuctural Completion

Precast Segmental Balanced

Cantilever

26 Why balanced cantilever?

Deep Bay Link

West Tsing Yi Viaducts

Span-by-span segmental

needs all of the segments in a

span to be simultaneously

supported by the gantry

Under some design

conditions this could lead to a

very expensive gantry:

- Long spans

- Tight radius curves

Shorter projects may not

justify investment

27 Shenzhen Western Corridor

28

Total only ~ 4 ½ years

• Feasibility Study (incl. Conceptual Design & EIA) Aug 2001 – Sep 2002

• Detailed Design Jul 2002 – Jul 2003

• Construction (Gammon-Skanska-MBEC JV) Aug 2003 – Dec 2005 (28 months)

Fast Track Design & Construction

29

30 Segment erection

31

Cantilever tip derricks Segment delivery by barge

Segment storage Short line segment match casting

End Spans

Expansion joints are needed at regular intervals which interfere with balanced cantilever erection

Options - Short end spans – interrupt the rhythm of the bridge

- Temporary fixity of joints

- Mid span hinge

- SWC – hybrid solution

33 End span erection

34

Hong Kong Zhuhai Macau Bridge

• 43.6 km bridge over Pearl River Estuary

• 1st major combined bridge & tunnel

sea-crossing in China

• reduce travel time to 0.5 hour

from HK and Pearl River West

Macau

Zhuhai

HKSAR

35

Lantau

Island

Macau

Zhuhai

Lantau Island

Qin

gzhou

navig

ation

channel

West Artificial

Island East Artificial

Island

Tunnel

HKBCF HK Section

36

37 Hong Kong Section

12km long highway

Including 9.4km sea crossing viaduct

38 Hong Kong Section

39

75m precast segmental balanced cantilever

Full Span Launching Method

41

42

Project Overview

Project Overview

43 Incheon Bridge

44

Full Span Launching Method

45

Launching gantry

46 Full Span Casting Factory

47

48 Pretensioning

49 Erection of first segment

50

Delivery of segments in deep water which is accessible by floating crane

Transportation along the already erected deck by a mutli-wheeled transporter

51

Segment transportation is governing load

1,300 tonne segment and 950 tonne transporter unit

Spread onto four girders

52

Erection equipment

Full Span Launching Method

Contractor was experienced with the method

Very long viaduct justifies investment in bespoke launching gantry to achieve very fast construction

No variations in deck width, no tight radius curves in highway alignment

Marine environment and availability of large capacity floating cranes

Low level viaduct makes moderate span length (50m) economical

Comparison of Sea Crossing

Construction Methods

55

Project Second Penang

Bridge Incheon Bridge

Shenzhen

Western Corridor

Deck Type Precast Concrete Box Girder

Procurement

Method Design & Build Design & Build Engineers Design

Contractor UEM Builders Samsung

Construction JV

Gammon-Skanska-

MBEC Joint Venture

Construction Method Span by span

precast segmental

Full span precast

launching

Balanced cantilever

precast segmental

Status Under Construction Completed 2009 Completed 2006

Total Length 16.9 km 12.3 km 5.5 km

Viaduct Length 16.5 km 9.0 km 4.7 km

Width 2 x 14.0 m 2 x 15.7 m 12 x 16.05 m

Typical Span 55 m 50 m 75 m

Typical Bridge Unit

Length 330 m 250 m 590 m

Three sea crossings constructed in shallow water in East Asia

56

8092 segments

3 lines of 7 moulds per line (different fabricators)

Storage capacity for 780 segments (2 months supply)

Typical segment – 1 per day

Second Penang Bridge Precast Yard

57

360 segments

1 mould

Storage capacity for six segments (<2 weeks production)

One segment every 2 days

Incheon Bridge Precast Yard

58

Casting yard in mainland China

1,879 segments

6 moulds

Segment casting started well in advance of erection

Shenzhen Western Corridor

59

Project Second Penang

Bridge Incheon Bridge

Shenzhen

Western Corridor

Number of Spans 580 360 90

(Hong Kong section)

Number of Gantries 4 2

1 overhead gantry

+ 4 pairs of

cantilever derricks

Spans Per Gantry 145 180 16

Number of

Segments 8,092 360 1,879

Number of Moulds 3 x 7 = 21 1 6

Segments Per

Mould 385 360 313

Target Cycle Time 4 days per span per

gantry

2 days per span per

mould

1 week per span per

gantry

Theoretical Duration

at Target

Productivity

20 months 24 months 4.5 months

Three sea crossings constructed in shallow water in East Asia

60

Second Penang Bridge

Design & Build – contractor can tailor method

Contractor had previous experience of span by span segmental

Environmental impacts acceptable with a 55m span

Incheon Bridge

Design & Build – contractor can tailor method

Contractor had previous experience of full span launching

Large number of spans justifies investment in bespoke gantry

Shenzhen Western Corridor

Very fast track project - needs multiple gantries

Limited number of spans – hard to justify bespoke investment

Engineers design – needs flexible method

Environmentally sensitive mud flats needs longer spans (75m)

ard

Conclusions

With constant width and gentle plan curvature a typical span length of

50m to 55m can be constructed by any one of the three methods

Speed of construction depends on number of construction fronts so the

cycle time for a single gantry may not dictate project duration

Span by span segmental construction is a versatile method but span is

limited to around 55m

Span by span segmental can be significantly accelerated if required once

construction team has gone through learning curve

Balanced cantilever will be more economical at longer spans

Full span launching will only be economical for very large projects which

tends to limit the number of contractors who will adopt it

Harder to accelerate full span launching

Emerging Trends

63 Stainless steel reinforcement

Extension of Design Life Asset Management

Structural Health Monitoring Threat and Vulnerability Assessment

Thank You