Construction of Bridges
Materials suitable for the Construction of Long-span Bridges 1. Stone – in arch masonry 2. Stee Steell – in gi gird rder er or bo boxx-se sect ctio ion n con const stru ruct cted ed in st stee eell plates and standard sections 3. St Stee eell – tr trus usss co cons nstr truc ucte ted d of st stan anda dard rd se sect ctio ions ns 4. Re Rein info forc rced ed Co Conc ncre rete te – in ar arch ch or sp span anne ned d fo form rmss 5. Tensioned RC RC – in va various fo forms 6. Pr Prec ecas astt – mai ain nly in bo box x-s -sec ecttio ion n gir irde der r
Materials suitable for the Construction of Long-span Bridges 1. Stone – in arch masonry 2. Stee Steell – in gi gird rder er or bo boxx-se sect ctio ion n con const stru ruct cted ed in st stee eell plates and standard sections 3. St Stee eell – tr trus usss co cons nstr truc ucte ted d of st stan anda dard rd se sect ctio ions ns 4. Re Rein info forc rced ed Co Conc ncre rete te – in ar arch ch or sp span anne ned d fo form rmss 5. Tensioned RC RC – in va various fo forms 6. Pr Prec ecas astt – mai ain nly in bo box x-s -sec ecttio ion n gir irde der r
Common Bridge Forms
Simple Supported – span effective from 10m to 60m Actual example – Route 3 Interchange at Au Tau, Yuen Long
Continuous Span – from 10m to 100m Actual example – construction of a span of continual section of elevated highway bridge at Route 3, Kwai Chung
Balanced Cantilever – span from 25m to 200m Actual example – balanced cantilever bridge series forming the approach to the Ting Kau Bridge
Balanced cantilever bridge for viaduct of West Rail at Au Tau Interchange
Balanced Cantilever Suspended Span – span from 50m to 300m
Steel Truss – 50m to 100m
Actual example – 5-span steel truss bridge in western part of Pearl River, Guangzhou
Steel Arch (framed or trussed) – from 150m to 500m
Sydney Harbour Bridge and its approach
Close up view of the bridge trusses
Close up of the bridge at the tower support
Cable suspension – from 400m to 1500m
The 1377m span Tsing Ma Bridge
Concrete Arch (ribbed or unribbed) – from 50m to 300m
Steel Arch – from 100m to 500m
The actual example – LuPoa Bridge, Shanghai (550m main span)
Cable stayed (multi-spanned) – from 50 to 500m per span
The 3-span cable-stayed Ting Kau Bridge
Cable stayed span – from 200m to 800m Actual example – the connecting bridge from Macau Mainland to the Island of Taipa in Macau
Example of box-sectioned steel girder bridge
Structural Elements for Typical Bridges 1. Foundation –for bridge towers, portal frames or piers 2. Bridge Tower – the vertical supporting structure for cable suspension or cable-stayed bridges 3. Pier – the vertical supporting structure for usual spanned bridges 4. Portal frame – cross beam between piers to support the deck 5. Bridge deck – the horizontal part of a bridge that support pedestrian or traffic activities 6. Bridge anchor – required only for suspension bridges to counter resist the pull from the suspension cable 7. Suspension cable – for suspension and cable-stayed bridges for the hanging, support or counter-balancing of the bridge deck
The foundation of the bridge tower of Ting Kau Bridge on Tsing Yi side
The foundation for the Bridge Tower of Tsing Ma Bridge on the Tsing Yi side
Forming the foundation for piers of elevated highway bridges
Pier supports for an elevated roadway
A portal frame serving also as a transfer beam in the Route 3/Airport Railway at Kwai Chung
Falsework for the construction a portal frame
Bridge tower for Tsing Ma Bridge and Kap Shiu Mun Bridge Tsing Ma Tower
Bridge tower for Stonecutter Bridge
Bridge tower & side span/approach bridge of Stonecutter Bridge
The forming of the cable anchor of Tsing Ma Bridge on Ma Wan side
The forming of the cable anchor of Tsing Ma Bridge on Tsing Yi side
Forming the deck of the approach section of Tsing Ma Bridge on Ma Wan side using erection and hoisting approach
Forming the deck of the approach section of Tsing Ma Bridge on Tsing Yi side
Completing the deck of Tsing Tsi ng Ma Bri Bridge dge (ab (abutt utting ing sectio sec tion n at at Tsin Tsing g Yi sid side) e) by erecting of the steel truss at spot
Hoisting and erecting of the modulated bridge deck for the Tsin Ts ing g Ma Br Brid idge ge
Forming the bridge deck of Ting Ti ng Kau Kau Br Brid idge ge usi using ng modulated steel girder frames
Laying the precast deck of the steel girder frame
Other methods to form the deck of bridges 1. Balanced cantilever method 2. Construct in-situ 3. Construct using precast beam 4. Construct using precast girder section and erected by a launching machine (viaduct) 5. Construct using incremental launching method
(the photos of project cases as shown in the following pages are for reference only in order to help students to understand more about bridge construction)
Forming the deck of the Ting Kau Bridge approach section using a special balancedcantilever traveling formwork system
The Ting Kau Bridge approach section
Construction of a section of elevated railway track in the KCR Ma On Shan Line using in-situ method
The laying of precast beams to form the deck of the Route 3 elevated roadway at Kwai Chung
Hoisting of the precast beams using a special launching gantry
Construction of an elevated highway bridge using precast girder erected by the use of a launching machine
Launching gantry used to erect precast girders to form a span of an elevated bridge (viaduct)
A bridge in the Fo Tan Road Improvement Project making use of Incremental Launching method to span across the servicing KCR rail line
Alignment of servicing rail line
– elevated roadway constructed in the form of viaduct
Route 3 – Kwai Chung Section
Route 3 – Country Park Section at Au Tau Interchange
Hung Hom Bypass
Tsing Yi North Coastal Roadway
Highway project in Ma On Shan
Launching gantry used in the Hung Hom Bypass
Launching gantry used in Route 3 at Au Tau Interchange
Launching gantry used in Tsing Yi North Coastal Roadway
Launching gantry used in the Ma On Shan highway project (T7)
Launching Gantry used in the Route 3 Kwai Chung section
Launching Gantry used in the Route 8 Tsing Yi Section
Layout of the bridge approach/interchange
(SWL = 105 T) Slave winch
(For end span and 1st pair segment erection) Hangers Main Truss
Front support
(SWL = 120T) Master winch
116m long
Rear leg
Rear support
Elevation of the Launching Machine
Front leg
A review of other highway and railway bridges – construction of the viaduct systems for the West Rail projects
Viaduct for railway track of the Kowloon Canton Railway West Rail at the northwestern part of the New Territory, Hong Kong
Some sections of viaduct spanning more than 40m at Au Tau Interchange
Forming the viaduct for railway track using the underslung girder and longitudinal beam supported method
Erection of the viaduct using balanced cantilever arrangement with temporary anchor before completion of a span
Precast box girders used for the viaduct
A section of viaduct with provision for an extension to the future northern link
Construction of some sections of elevated railway track using in-situ method
Constructing the linking bridge between Tung Chung and Chek lap Kok (the Airport Railway) using Incremental Launching method
Trends in the Construction of Bridges in HK Construction of large and long-span bridges is of no doubt a part of the major infrastructure development for a city, which is, again, a reflection of the economical climate and development strategy of the area. On the construction side, the limited land reserve in Hong Kong does imposes stringent conditions especially where the options and cost effectiveness of constructing a bridge is concerned. To cope with these considerations, a few world-class bridges over 1000m span are yet scheduled for completion in the coming decade, in view of keeping Hong Kong to be competitive in particular within the highly economic-active region in the southern part of China. The construction of these bridges is, without much choice, in the form of either cable-stayed or suspension bridges.
The construction of other medium to short-span bridges are becoming much popular recently as part of the highway improvement strategy in Hong Kong. The shortage of space for highway improvement works, the involvement of complicated interchanging provisions, the familiarization of bridge construction techniques in catering various local constraints with acceptable cost, are factors that made bridges of this type becoming popular. Some inherited difficulties such as the requirement of large amount of working spaces for the forming, transporting and storing of the roomy precast elements; the operation of the launching works, or arrangement for traffic diversion within existing busy roadway, still makes roadwork under urban environments complicated and costly. Needless to mention working in environmental sensitive locations such as where protection to natural habitats or rural culture is required; or where waste, noise and dust problems are of ultimate concern.
The cost for constructing bridges are unavoidably high in particular working within congested and complicated urban environment like Hong Kong. As a tradition, bridges and elevated highway structures in Hong Kong are mainly constructed in concrete. As a cost saving option, steel bridge, say, in hollow section, box-girder or any other feasible design, may be alternative choices for highway bridges, like those commonly used in Mainland China or Japan. The saving in initial cost and construction time of using such alternatives may provide surplus capitals and expedite the ongoing infrastructure projects, this is essential especially in the forthcoming years when the economic situation is expected to be less favourable than before.
