Bridge designers are getting bolder in their dynamic demands and one of the common approach is to design bridges with stay cable. Not only can they overcome engineering difficulties, cable stayed bridge also add the aesthetic effects to the bridge construction. And very often, mega cable stayed bridges turned out to be outstanding landmarks attracting scores of visitors.
In this post, we show some production processes on our pre-fabricated stay cable productions. TMG Stay Cable produced with 7-wire high tensile steel cable (PC strand) made up about 80% of all our stay cable production. And of these, more than 50% are pre-fabricated stay cables.
Pre-fabricated stay cable offers a fast and efficient solution to small and medium-size cable stayed bridges. It eliminates the requirement for heavy lifting crane and machinery. It also reduces the total manpower and on-deck carbon footprint. And the most attractive factor is the fast turn-around time as compared to on-site installation stay cable. There is no requirement for on-site strand-by-strand prestressing or post tensioning work.
Pre-fabricated stay cable manufactured under factory conditions, is also more consistent with quality, waterproofing, finishing and performance.
PC strand is widely used in prefabricated or precasted concrete elements like hollow core slabs, girders, beams, railway sleepers, foundation piles, poles etc., and also in post tensioning constructions such as bridges, buildings, dams, tanks, silos etc. And also as tendons in bridge cable or stay cable. Its application is far and wide, both for pre-tensioning and post tensioning, bonded and unbonded applications.
TMG is one of the world largest PC strand manufacturer, our Low Relaxation 7-wire PC strand are manufacture with high quality wire rod in a variety of steel grades. In 2014 alone, we produced over 330,000 ton of PC strand and shipped to more than 35 countries around the world.
TMG is capable of producing PC strand with these standards ASTM A416, BS 5896, JIS G3536, AS/NZS 4672.1, EN 10138 etc., with a variety of sizes. Ranging from 9.30mm to 28.60mm in diameter. And all PC strand are delivered in precision wound coils with excellent pay-off properties. Standard coil weight is around 3 tonnes. Special coil weight is also available on request. And anti-rust proofing is also a common practice for coils that requires longer transhipment duration.
Below is a video showing our manufacturing facilities.
Cable Stayed Bridge is a kind of bridge formed by the combination of tower and bridge cable, to support the deck of the bridge. Its structure is developed through the load bearing of the tower, tension of the bridge cable and the bending of the deck beam. It can be understood as the bridge cables replacing bridge columns / piers, in a multiple span context. The advantages are
- reduced bridge deck size
- reduced structure height
- reduced overall structure weight
- reduced usage of construction materials
Cable Stayed Bridge can be classified into 3 classes, namely parallel type, fan type and star type. In parallel type, the stay cables are almost parallel and the height of their attachment to the tower is proportional to the distance from the tower to their deck mounting location. As for the fan type, the stay cables are all connected to or pass over the top of the tower. Lastly is the star type.
Stay Cable layout can also be further classify into 3 different types,
The earliest cable stayed bridge dates back to Sweden’s Strömsund Bridge built in 1956 with a main span of 182 meters. Half a century later, the rapid development of stay cable technology had seen the construction of 200 over cable stayed bridges with span of 200 meters or more. And 100 over cable stayed bridges with span of 400 meters and more. Examples of these mega cable stayed bridges are, France’s Pont de Normandie Bridge in Normandy with span of 856 meters, China’s Sutong Bridge in Jiangsu Province with span of 1088 meters, and Russia’s Russky Bridge in Vladivostok with span of 1104 meters. Currently, Russky Bridge is the largest cable stayed bridge in the world.
Cable stayed bridge is one of the most prominent application for stay cable system. Its span distance is a lot further than traditional bridge, which is typically about 40 – 50 meters. And there are also a few types of tower to cable stayed bridge, namely
- Single ‘I’ type
- Double “I’ type
- ‘A’ type
- ‘Y’ type
- ‘H’ type
- Portal type
- Diamond type
And these bridge towers can be constructed by reinforced concrete or steel structure. The usage of PC wire in stay cable had also been transformed to the usage of PC strand. And this transformation has further increased the efficiency of stay cable fabrication and installation. Epoxy coated PC strand further increased the lifespan of these stay cable and this innovation greatly reduces the maintenance and cost that comes after the construction of these bridges.
Stay cable utilizes the ‘self-anchorage’ concept, similar to post tensioning way of anchorage. However in recent years, there is a trend of self-anchoring stay cable, coupled with ground anchor technology. Example is Barrios de Luna Bridge in Span with span of 440 meters. The usage of ground anchor technology into stay cable system originated from the concept of suspension bridge. The two end of the main cable of a suspension bridge is normally split up into many smaller bundle of cables which are driven into the ground. And it is these small bundles of cables anchored into the ground (that is why the name ‘ground anchor’) that holds the load of the whole bridge deck. By incorporating ground anchor technology into cable stayed bridge, it allows the stay cable positioning on the deck to be more optimum in relative to the geographical situation of the bridge. Making the stay cable configuration more versatile and also with reduced usage of material.
In general terms, cable stayed bridges is most suitable for span distance of 300 – 1000 meters. And it is more prominent when cable stay bridge is in comparison to suspension bridge under this range. Renowned structure engineer and bridge designer, Mr Fritz Leonhardt, even commented that cable stayed bridge of span 1400 meters uses 50% less in high tensile strength PC wire as compared to suspension bridge. And with a 30% reduction in construction cost.
Over the last 50 years, the development of stay cable technology has advanced by leaps and bounds. And it is in the human race that we will continue to push for cable stayed bridge to have
- span distance above 1000 meters
- more efficient and lighter structures
- improve corrosion protection to stay cable
- more flexibility and versatility to stay cable features
- safer and greater control during stay cable installation
- and more influence to stay cable behavior under adverse environment
Here are some production photos of our stay cable system.
E-Force Engineering Pte Ltd, our longtime strategic business partner, was presented with Luminary Class Award during Singapore Prestige Class Awards 2014 – 2015 Ceremony in Shangri La Hotel on 9th April 2015.
E-Force is a specialist post tensioning company with presents in Singapore, South-East Asia and many parts of Middle East. They specialised in prestressed concrete structural works, primarily for buildings, logistic warehouses, parking facilities, and other special structures. Some of their prominent projects are; the largest mall (Safeer Mall), the biggest Islamic Mosque (Sheikh Zayed Islamic Centre) in Fujairah, as well as the largest resort development (Mina Al Fajer) in Dibba, United Arab Emirates. The prominent Al Hussain Tower in Olaya area, Riyadh, Kingdom of Saudi Arabia, is also one their many achievements.
E-Force’s deep understanding of prestressing work and diverse knowledge on structural works made them the preferred choice among the post tensioning specialists in many regions. And equipped with a complete range of Stressing Jack and other accessories, E-Force is ready to undertake any type of post tensioning works with its certified European Technical Approval (ETAG 013) system.
Having worked along with E-Force team of committed members since their establishment, TMG Global Pte Ltd is confident that E-Force will continuously bring benefits and values to the construction industry.
Moving ahead, TMG and E-Force is embarking on another milestone on Bridge Cable construction. We had seen the dramatic increase in Stay Cable demands over the last few years. And the dynamic requirements to these challenges prompted for more creative and ingenious solutions to meet these ever-changing demands. TMG had since developed a Compression Fitting Stay Cable System in view of this trend. Using the same working principle for anchorage with PC Wire, Compression Fitting Stay Cable System uses PC Strand to further increase the working and dynamic load. And this revolutionary innovation elevates further enhance the dynamism in Cable-stayed bridges.
Lastly, we wish E-Force Engineering Pte Ltd every success on their endeavouring path.