Resumen de Assessment and strengthening experience with bridges in Germany

Michael Müller, Volkhard Angelmaier, Wolfgang Eilzer

• Repair and maintenance of bridges gain constantly importance for the infrastructure sector. Considering the 40.000 bridges of federal highways in Germany; their functioning is the mandatory basis to ensure the mobility of a modern society. After having built up and expanded successfully the road network in the eastern part of Germany strengthening of existing structures in the western part of Germany became the big challenge for the near future.

  The strengthening of bridge structures need to be guided by a holistic approach. Therefore, the whole spectrum of the engineering disciplines starting with evaluation and finishing with the professional execution of the works is required. It is essential to have a close coordination between different disciplines:

  • Inspection, monitoring, • Evaluation and rating, • Planning and checking.

  The need for strengthening of a structure can get initiated by various reasons:

  • Low rating, emergency repair.

  • Increase of the overall capacity for higher live loads • Rehabilitation • Repair of specific deficits • Provision against future damages.

  The services to the Bridge Departments comprise the following steps.

  • Complete inspection according DIN 1076, • Analysis and evaluation according to “Nachrechnungsrichtlinie”, • Design and tendering of rehabilitation and repair works, • Design and tendering of immediate repair works to stop increasing damages to the structure, • Planning and implementation of a monitoring program in relation to dynamic loading and fatigue issues.

  With two examples, the Kochertalbridge and the Rhine Bridge Cologne- Mülheim, we will present a couple of specific experiences related to the strengthening topic.

  The Kochertalbridge (Fig.1), built as prestressed concrete structure was built in the 1970s with an overall length of 1128 m and a maximum of 185 m above the valley is the highest viaduct in Germany. Due to increasing traffic loads, the viaduct had to be rehabilitated.

  The approx. 1054 m long Suspension Bridge Cologne-Mülheim (Fig.2) is a steel bridge with at total length of 485m and a main span of 315m. After more than 60 years of service and increasing traffic loads the Mülheim Bridge, listed as historic monument, has to be recalculated, refurbished and strengthened to ensure the future longterm serviceability of this important river crossing.

  The presentation will focus on the wide range of engineering services involved in such a rehabilitation planning of and the specific experience gained through strengthening projects.