HRA Ingenieurgesellschaft, headquartered in Bochum and Mainz, offers a diverse range of services from structural planning through testing to construction monitoring and building inspection. The company can point to many successfully completed projects in bridge construction, industrial and structural engineering, as well as in hydraulic engineering. The engineering office currently employs around 20 staff and is engaged, alongside classical planning and construction, in research, software development and on standards committees.
Its current projects include the 1,702 meter long High Moselle Bridge in Rhineland-Palatinate, being built on behalf of the Rhineland-Palatinate State Mobility Authority. A new connection for federal highway 50 (B 50n) over the Moselle valley will be created between Ürzig and Zeltingen-Rachtig, planned to be opened for traffic in 2016. The new road bridge, which crosses both the Moselle valley, federal highway 53 and local road 189 with in total four lanes and two hard shoulders, is the core of the third construction phase of the new-built section known as the “High Moselle Crossing” on the B 50n (section IIb). Under the leadership of Eiffel Deutschland Stahltechnologie, Hanover, it is above all mid-sized firms that are being entrusted with the realization of the laborious construction measure, having started in April 2009 with the planning and execution of the 360 million Euro construction project. The task of HRA Ingenieurgesellschaft: Statics testing and various detailed investigations of the bridge structure. The programs PONTI® and TRIMAS® by the Stuttgart provider RIB Software AG, which are among the standard repertoire of software tools used at the company, were used by the engineers in this project for numerous calculations.
The planned steel beam bridge, 1,702 meters long with an orthotropic roadway, is constructed as a continuous beam lengthwise, consisting of eleven sections in total of very large spans. Its cross section is in box girder design. In total, ten reinforced concrete pillars with a maximum height of 158 meters will carry the new bridge over the Moselle. With the addition of the foundations of over 50 meters at this highest point, the maximum height reaches 200 meters. For these foundations, the plans foresee the use of large-scale bored piles. For construction of the superstructure, with a mass of approx. 25,000 tons, the incremental launch procedure will be used. At the Hunsrück abutment, it will be constructed in sections and subsequently inserted.
A bridge that has set a European record: For it has the largest span ever ever crossed by incremental launch without auxiliary support from an assembly location set up on the south-east side of the Moselle valley: 210 meters, believe it or not. From this point, the construction company Eiffel Stahltechnologie will assemble in total 82 sections of almost 21 meters. For each of the ten bridge columns, a separate forward jacking system is intended. The jacking is hydraulically controlled. The reason for this complexity: No forces may be directed into the subsoil.
The calculations for this demanding tasks are the responsibility of both the assessors from HRA and the structural planners from Klähne Beratende Ingenieure im Bauwesen, Berlin. Dr. Berthold Dobelmann of HRA explains the task and the complexity of the calculations: “Both ends of the superstructure, at the abutments with axes 0 and 50, allow deformations of 55 centimeters each. That means that, depending on the type of load, for example, wind, temperature or the forces exerted by traffic, the bridge will get correspondingly longer or shorter. It is our task to exactly determine the limits of movement at both abutments in the end state, that is, when the bridge is opened for traffic.” To this end, the engineers analyzed three separated cases. First, the forces acting on fixed pillars 3-6; second, all forces that act on axis 50 at the abutment, and finally all the forces that act on the abutment at axis zero. The superstructure is manufactured at the Hunsrück abutment at axis 50 (south-east). The superstructure is jacked forward segment by segment towards the Eifel abutment at axis zero.