Hochmosel bridge
RIB programs support engineers in demanding Inspection analysis Tasks
HRA Ingenieurgesellschaft - a versatile engineering company
HRA Ingenieurgesellschaft, based in Bochum and Mainz, offers a wide range of services from structural design and testing to construction supervision and acceptance. In bridge construction, in industrial and structural engineering as well as in civil engineering and hydraulic engineering, the company can boast a large number of successfully completed construction projects. The engineering office currently employs around 20 people and, in addition to classical planning and construction, is also involved in research, the development of software programs and in standards committees.
New "Hochmoselübergang" section with 1,702-metre-long viaduct
Current projects include the 1,702-meter-long Hochmosel Bridge in Rhineland-Palatinate, which is being built on behalf of the Rhineland-Palatinate State Office for Mobility. A new connection of the federal highway 50 (B 50n) across the Moselle valley is being built between Ürzig and Zeltingen-Rachtig, which is expected to be opened to traffic in 2016. The new road bridge, which with a total of four lanes and two hard shoulders next to the Moselle Valley crosses the federal highway 53 as well as the state highway 189, is the heart of the third construction phase of the new "Hochmoselübergang" section on the B 50n (section IIb). Predominantly medium-sized companies, which began planning and construction of the approximately 360 million Euro construction project in April 2009, were entrusted with the realization of the complex construction project under the leadership of Eiffel Deutschland Stahltechnologie, Hanover. The task of the HRA Ingenieurgesellschaft: The inspection analysis as well as various detailed investigations of the bridge structure. The engineers used the programs PONTI® and TRIMAS® of the Stuttgart-based supplier RIB Software AG, which belong to the standard repertoire of software tools used in the company, for numerous calculations in this project.
Figure 1a: Highway network with route B50neu
The Hochmosel bridge in numbers
The planned steel beam bridge with a length of 1,702 metres and an orthotropic carriageway slab has the continuous girder as the structural system in the longitudinal direction and consists of a total of eleven spans with very large span widths. A box girder cross-section is provided for the transverse direction. A total of ten reinforced concrete piers with a maximum height of 158 metres will support the new bridge over the Moselle. If the foundation of around 50 metres is added at this highest point, the maximum height is 200 metres. The planning envisages large bored piles for this foundation. For the assembly of the superstructure with a mass of approx. 25,000 tons - according to the planning specifications - the incremental launching method will be applied. At the Hunsrück abutment, this is to be assembled in sections and then inserted.
Largest feed field to date in Europe
A bridge that even sets a Europe-wide record: This is because the largest field, which is advanced from a pre-assembly site erected for this purpose on the south-east side across the Moselle opening without additional auxiliary support, is no less than 210 metres. The contractor, Eiffel Stahltechnologie, will assemble a total of 82 shots with an average shot length of almost 21 meters from this point. A separate feed device is provided for each of the ten bridge piers. The feed is effected via a hydraulic control system. The reason for this complexity is that no forces may be transmitted into the ground.
The calculations for this demanding task are carried out by the HRA inspectors and the structural engineers of Klähne Beratende Ingenieure im Bauwesen, Berlin. Dr. Berthold Dobelmann from HRA explains the task and the complexity of the calculations: "Both ends of the superstructure at the abutments on the axes zero and 50 allow deformations of 55 centimeters each. This means that, depending on the type of load, for example wind, temperature or the loads generated by traffic, the bridge will be longer or shorter. Our task is to precisely determine the movement limits at the two abutments in the final state, i.e. when the bridge is completed and released for traffic." For this purpose, the engineers analysed three separate cases. Firstly, the forces acting on the fixed piers 3-6, secondly, all forces acting on the abutment on axis 50 and, finally, all forces acting on axis zero. The superstructure is produced at the Hunsrück abutment in axis 50 (southeast). Towards the Eifel abutment in axis zero, the superstructure is moved forward field by field.
Figure 3: System sketch for feed, feed device and subsoil
Figure 4: Pillar in structural state and FE model for non-linear deformation calculation controlling huge forces
The forces acting on the bridge due to its specifications are all huge. Therefore, the tender for the bridge structure designed by the Düsseldorf office of Schüssler-Plan, which was adapted to all current standards according to the design, stipulates that stability must be guaranteed. Even in the event that fixed pier no. 3 on the north-west slope attacks with a 30 centimetre offset. The nature of the ground makes such a "safety calculation" necessary. Because the subsoil of the partly weathered clay slate is considered fragile. For this reason, the foundation at this point must also protrude far into the depth, because only the slate horizon further down offers the necessary load-bearing capacity.
Bridge substructure: drilled piles with a lot of reinforcement
For the bored pile system of the substructure of the transversely parabolically curved bridge HRA and the structural engineers of EHR Beratende Ingenieure für Bauwesen from Stuttgart calculated the necessity for the use of an enormous amount of reinforcement. For two reasons. "First of all, the design specifies very slim and visually appealing bridge piers. For the substructure to meet the specified standard, extreme load cases must be taken into account in the partially non-linear calculations," explains Markus Kubitza from HRA, who is responsible for the substructures. The calculations serve here as a basis for the Austrian PORR AG, which will carry out the erection of the substructures in coordination with the project coordinator Eiffel.
Powerful software systems provide support
Engineers and construction companies are all required to perform these tasks. The calculations are tricky and, at the same time, it is important for the construction work to make these highly technical engineering services a reality with the appropriate processes. These are challenges for which the use of powerful software systems for planning and construction provides comprehensive support in many areas.
Figure 5: FE-model for bridge superstructure with different construction stages
Simply combine load cases with PONTI®
Dr. Dobelmann explains how the RIB programs, in this case the PONTI® software, support the HRA's complex and complex static testing tasks: "Only for the superstructure did we have to consider more than 200 different construction stages. First 130 sections, as the calculation was carried out in 13-metre steps. But that's not all: the engineers also examined about eight to ten other states for each individual construction stage due to the different load cases that could affect the bridge. "With the PONTI® software, we can combine these relatively easily," adds the expert. "This enabled us to work faster and more accurately at the same time," he summarizes.