Curved, partly asymmetrical bridge for tram rail traffic
Räisälänsilta is a circa 200-meter long, 7-span cantilever-constructed concrete bridge crossing Ringway I between the districts of Otaniemi and Laajalahti in Espoo, Finland. The project is part of a larger Jokeri Light Rail public transport project to connect the cities of Espoo and Helsinki. Ramboll Finland provided geotechnical and structural design for the substructures and superstructures of the bridge. The design started in the beginning and the construction in the end of 2019. The bridge structures use circa 2000 m3 of concrete and nearly 200,000 kg of reinforcements.
It was a challenge to design the bridge due to its multiform curved deck and irregular column geometry. Dedicated to tram rail traffic alone, the bridge needs to bear significant loads. Its design required close coordination with rail and electrical engineering and other engineering disciplines, and it was necessary to work flexibly on the project and provide quick updates to the building information model.
The bridge was completely modeled in great detail including every nut, bolt and reinforcing bar, by using the Tekla Live Link tool with Grasshopper. The bridge model was exported to Trimble Connect and combined with the rest of the models created for the Jokeri Light Rail project.
Parametric features and Tekla Live Link enabled fast, accurate modeling
The greatest challenge in the project was to create the geometry for the curved forms and columns of the bridge and to model their reinforcements, railings, pipes and other fixings accurately. Modeling the thousands of unique parts using various work planes and coordinate axes was challenging, and the ability of the software to model all orthodoxly turned out to be a decisive success factor.
The parametric features of Tekla Structures software (version TS2018 SP9 Finland) and Tekla Live Link enabled fast, accurate modeling and quick updates without having to repeat any work phases. Trimble Connect was used extensively to combine and check the models. Tekla Live Link enabled combining the best qualities of Rhino and Tekla so that Rhino was used for modeling the complex geometry and Tekla to accurately detail the structures. Using BIM enabled studying the model and the design in great detail and identifying the matching problems in the irregular geometry.
The main contractor encouraged the teams to use BIM throughout this cooperative project. Cooperation was fluent and effective between the project architect and structural designer. The architect’s design updates were communicated to the project team as AutoCAD drafts and by directly consulting the designer. The design team used IFC models and Trimble Connect for communications.
Urban, geotechnical and structural design: Ramboll Finland Oy
Contractor: GRK Infra Oy