The partial collapse of Dresden's Carola Bridge has reignited the debate about the condition of bridges in Germany. According to a study* publishedby Südwestdeutscher Rundfunk (SWR), there are around 130,000 bridges in Germany. Almost 12 percent of these are in a dilapidated condition and in need of renovation. In view of the resulting growing order situation, bridge construction is increasingly coming into focus for planning and engineering firms and is facing a number of challenges, as planning is often still carried out in 2D. The Kiel-based engineering team Trebes took the step from 2D planning to 3D planning back in 2017. With the BIM software Tekla Structures from Trimble and a continuous expansion of BIM-based planning, the engineering firm is also successfully positioned in bridge construction.
Since its foundation in 1971, the Trebes engineering team has always aspired to be at the forefront of technological innovation. With success: 93 employees at five locations in Germany today cover a wide range of services and support customers in all structural engineering planning in building construction and structural engineering, including implementation planning for in-situ concrete, prefabricated construction and steel construction. The projects range from industrial and commercial buildings to larger residential construction projects, bridges and other engineering structures. in 2017, Trebes decided to introduce the 3D BIM software Tekla Structures from Trimble, making it one of the pioneers in the construction industry when it comes to BIM-based planning.
3D planning in bridge construction - the decisive dimension more
In bridge construction, the engineering office works primarily with public clients. In addition to smaller steel bridges and corrugated steel structures for pedestrians and cyclists, the team plans reinforced concrete road bridges and replacement bridges (including dismantling). For some time now, Trebes has seen an increasing number of orders in bridge construction - unlike in building construction, for example. The first clients are already demanding BIM-capable software, but 3D-based planning is not usually mandatory in bridge construction and 2D drawings are often still standard. Nevertheless, the engineering office is already using the Tekla 3D model and sees many advantages.
This is because planning in 3D makes it possible to visualize bridge structures in more detail and better, which enables more precise planning and more efficient implementation. In addition, potential problems and collisions can be identified and resolved earlier, before construction begins. In addition, BIM promotes collaboration and communication between the various project participants and enables better coordination and control of the project. Nina Precht, a design engineer who has been responsible for bridge projects at Trebes for many years, sees the benefits for her work over the entire course of the project: "The integration of 3D models into the bridge inspection simplifies the process and enables continuous monitoring of the bridge over its entire life cycle. And problems become apparent as early as the design phase that you would otherwise only have thought about during construction. We can also visualize and explain them more easily on the model without having to read the technical drawings."
"Working with Tekla Structures allowed us to precisely plan and coordinate all aspects of the project. From the modeling of the old and new bridge to the design of the temporary bypass, we were able to specify all the details precisely, ensuring an efficient and successful replacement."
Nina Precht, design engineer, Trebes engineering team
Nina Precht experienced the switch from 2D to 3D herself. She planned her first project with Tekla Structures in 3D back in 2017. "When planning in 2D, I often struggled with complex, tricky areas. In 3D, I can solve them and display them precisely in the model and on the plans." She adds: "Like all areas of the construction industry, bridge construction is under time and cost pressure. The deadlines are very tight and changes can be made to the project at any time. Implementing these in 2D is a major challenge because I have to redraw every line. In addition, collisions often only become apparent on the construction site. In Tekla Structures, on the other hand, all components, drawings and reports are automatically adjusted when changes are made."
Solid planning - that is flexible at all times
Advantages that have already proven themselves in many projects at Trebes, including the BW 506 replacement project, where Nina Precht used Tekla Structures and Bridge Creator for the complete bridge design. The Bridge Creator is a powerful tool that is integrated into Tekla Structures. It allows complex bridge structures - regardless of material and size - to be designed and visualized in 3D. The road geometry can be imported, for example as a LandXML file, and the cross-section along the road geometry can be created automatically.
The BW 506 replacement project involved a 2-span prestressed concrete bridge from the 1960s that crossed the A7. The bridge had been severely damaged over the years and could only be used to a limited extent due to considerable damage. "In view of the stress corrosion cracking of the Carola Bridge, I am very pleased that this old bridge has now been replaced," explains Nina Precht.
Bridge Creator was used for the superstructure and alignment. First, Nina Precht modeled the old bridge in Tekla Structures on the basis of old construction plans in order to determine the quantities of concrete required for the demolition. The new superstructure was then modeled using a reinforced concrete composite (steel girders, prefabricated slabs, in-situ concrete). As the bridge is an important traffic link, it could not be closed for the duration of the construction work. Therefore, a temporary bypass was modeled in Tekla Structures to ensure that traffic could flow smoothly during this time.
"Working with Tekla Structures allowed us to precisely plan and coordinate all aspects of the project," explains Precht. "From the modeling of the old and new bridge to the design of the temporary bypass, we were able to pinpoint all the details to ensure an efficient and successful replacement."
An additional challenge for this project arose two weeks before the deadline when the temporary bridge was converted from a single-span bridge to a double-span bridge. The cofferdam and sheet piling had to be adapted and an additional central support and a new construction pit had to be planned. With Tekla Structures and the 3D model, it was possible to make these changes in a very short time.
The future lies in 3D planning
As digitalization progresses and the BIM method becomes increasingly important, the industry is at a turning point. Companies must decide whether to stick to traditional working methods or take the leap into the digital future and remain competitive. For the Trebes engineering team, it is clear that there is no way around BIM in order to be successful. "We are looking forward to being part of the change and actively contributing to making bridge construction more efficient and safer," says Nina Precht.
Ultimately, the switch to planning in 3D and BIM is not just a question of technology, but also of attitude. Everyone involved in construction must be convinced by the BIM method and be prepared to rethink familiar working methods and make them fit for the future. The change must be gradual and structured and is not just a matter that affects planners and contractors; existing standards must also be adapted.
* Source: Frankfurter Rundschau
Image material: Trebes engineering team
Find out more in the webinar. Bridge expert Michał Jednicki gives you insights into project examples from Germany and shows how Tekla Structures and the Bridge Creator support the entire bridge construction workflow. Watch now for free! >>
