The Kelani Bridge – is an outstanding example of structural steel use in a mega viaduct. The new six-lane bridge showcases technologies used for the first time in Sri Lanka.
Its location posed a key challenge for the conclusion of this project. Construction kicked off on January 2018 in the northern part of Colombo, Sri Lanka. The works took place at a busy intersection merging four key locations: Colombo, Candy (the second largest city in Sri Lanka), Port of Colombo and the International Airport. On November 24, 2021, an opening ceremony celebrated the new Kelani Bridge.
Using steel helped reduce construction time and minimise road closures and traffic constraints. Over 21,300 tonnes of steel were used for the entire structure, including a steel box pier, a steel box girder and a composite deck system.
This project is unique for our member JFE Steel Corporation as it marks the very first time they supply such a large amount of 3,700 tonnes of Steel for Bridge High-Performance Structure (SBHS) 500 MPa-grade steel. Among the many benefits of the material, SBHS has high strength and excellent weldability, in line with the Japanese Industrial Standard (JIS G 3140) for the part of the main frame of the Pier and Girder structure.
In addition, the Steel Concrete Composite Deck slab (SCCD) system chosen offers high durability, also enabling road base construction without conventional formwork.
The entire steel structural viaduct consists of:
- 33 steel anchor frames,
- 4,000 tonnes of steel piers (16 portal frame piers and one inverted L-shaped pier),
- 14,200 tonnes of steel superstructure box girders with 202 bearings and 24 expansion joints. (11 multi-main box girder bridges in the main line section and 10 one-box girders in the ramp section),
- 40,000m2 of steel composite deck panel
Given the short fabrication period for 21,300 tonnes of steel piers, steel box girders and deck panels, the fabrication work was executed simultaneously at five factories in four countries: Japan, Myanmar, Vietnam, and Thailand. The fabricators were nominated based on several technical aspects, such as production capacity, process control, assurance of the quality control system, labour skill, and transportation route. The corner block of the pier was composed of complex multiple stiffener plates with critical design stress. Therefore the mock-up trial work helped to ensure a smooth assembly and welding sequence/positioning.
In April 2020, the site construction started amidst the COVID-19 pandemic. A conventional erection methodology was applied based on a bent support scheme. During the nighttime, several 250-ton all-terrains and crawler cranes were used and executed simultaneously in five separate zones considering existing traffic flow while avoiding road closures.
The structural behaviour due to the deflection and temperature variation during erection was analysed and demonstrated by frame analysis following the erection sequence. All the erection works for 21,300-ton steel components had been completed after 11 months in March 2021 with erection productivity of approximately 1,900 tonnes per month.