Bewertung einer alten genieteten Stahlbrücke – Die Bösebrücke in Berlin

Evaluation of an old riveted steel bridge – The Böse‐Bridge in Berlin, Germany. This report is about the recalculation of the Böse‐Bridge in Berlin which was built between 1912 and 1916. A special feature of this three‐bayed truss arch bridge is the nickel steel used in the main bay. Different models have been used to recalculate the main structure, the truss nodes and the carriageway slab. The static analysis is based on the semi‐probabilistic concept. As a result of this recalculation the construction was classified to have the bridge capacity 30‐30 according to DIN 1072. Finally, this report concludes by determining the remaining lifetime depending on the concept of the Wöhler curves.     

Zuverlässigkeitsorientierte Bewertung von Bauwerken auf Grundlage der Bauwerksüberwachung

Reliability‐based system assessment of civil engineering structures based on structural health monitoring The safety and usability of transport infrastructure is of great importance for the entire society, because disturbances of traffic networks can have significant financial and environmental consequences. Especially in times when bad news about deteriorated structures and shortened public budgets are omnipresent, innovated solutions are in demand. Structural health monitoring (SHM) can help to assess the safety of deteriorated structures. With the help of suitable monitoring strategies the service life, which may elapse up to a renovation or a renewal without endangering the users, can be determined. So far however a regular monitoring of buildings – with few exceptions – did not become generally accepted yet, above all because it is time‐consuming and expensive. Owing to world‐wide research and development in this field however inspection and monitoring strategies can be optimized meanwhile in such a way becoming attractive for various applications. Innovative methods for structural health monitoring (SHM) are developed by the Collaborative Research Centre (CRC) 477 at the Braunschweig University of Technology. In project field A1 a framework for the probabilistic safety assessment of structures based on data from SHM is developed. This paper describes and explains the methodology of the framework and shows its application using a substitute structure of the CRC 477 as an example.     

Gegenüberstellung der statischen Berechnungen einer Stahlbrücke nach DIN ‐Fachberichten und bisher gültigem Regelwerk

Structural analysis and design of a steel bridge – comparing the new standards with the previous ones. The DIN ‐Fachberichte were adopted in 2003 as new standards for structural analysis and design of bridges. Their application results in changes of loading, design methods and design of bridges compared to the previous regulations. This contribution will illustrate the effects of the new standards on the steel construction of a railway bridge by comparing its structural analysis and design both according to new standards and previous ones. As a result the comparison shows that mainly due to more conservative load distribution in the road bed the trackway needs to be reinforced.     

Korrosionsschutztechnologie für Montageschweißstöße einer feuerverzinkten Stahlbrücke

Corrosion protection technology for construction sites welded joints of a hot‐dip galvanized steel bridge. Current bridge structures are designed for a useful life of 70 to 110 years [1]. Organic coating systems, which are used for bridge structures, are limited in their corrosion protection period to approximately 25 to 35 years and require at least a two‐time renewing or partial renewing during the planned useful life of the bridge. These necessary works on the corrosion protection system causes costs which the bridge owner tries to avoid, partly by extending maintenance cycles, with corresponding consequences for the corrosion intensity in steel construction. The use of a corrosion protection system with a long term protection, which get along as far as possible without costs and time‐intensive maintenance during the useful life of the bridge construction, is therefore sensible. According to the latest research results, hot‐dip galvanizing is able to guarantee a 100 year protection period for bridge structures without maintenance. In order to be able to apply the retouch of the hot‐dip galvanizing in weld seam areas and partial imperfections (e.g. transport and assembly defects) by thermal spraying with zinc independently of the silicon content in the steel, a comprehensive process and technology development took place within the framework of two research projects. The research results show that weld seam areas and imperfections by thermal sprayed zinc coatings according to DIN EN ISO 2063 [2] with sufficient adhesion to a blasted steel and sweep blasted hot dip galvanized surface of structural steels in the low silicon, middle sebisty and high silicium range can be applied and quality standard corrosion protection systems can be prepared.     

Einsatz bruchmechanischer Methoden zur Bestimmung der Restnutzungsdauer von Windenergieanlagen

Application of fracture mechanics to the assessment of remaining life‐span of wind turbines. The assessment of cracks in steel tube towers of wind turbines by using models based on fracture mechanics is described. The presented concept can be used to determine the remaining life‐span of wind turbines. Maximum allowable crack dimensions are determined. Growth of the cracks up to these critical dimensions is investigated. For that purpose semi elliptic surface cracks are assumed in the welded joint between door frame and tower hull. Solutions for the stress intensity factor are used to describe the stress field at the crack tip. Input stresses are determined by linear‐elastic finite element calculation. The Failure Assessment Diagram (FAD) is used to determine critical crack dimensions. Crack growth is estimated considering stress ratio and s‐shaped dependency of crack growth rate on cyclic stress intensity.     

Beurteilung der Tragfähigkeit von geschädigten Stahlbetonbrücken auf der Grundlage der Ergebnisse einer Bauwerksprüfung

Structural Reliability Assessment of Damaged Reinforced Concrete Bridges on the Basis of the Results from a Bridge Inspection The regular bridge inspection is of high importance for the reliable use of the infrastructure. This paper describes and explains a method with supports the engineers of a bridge inspection in the assessment of the damaged bridges during or directly after the inspection. Based on this initial estimate the urgent measures i.e. a lower permitted bridge class can still be carried out before more detailed inspections and calculations have been done. The reliability analyses for the damaged bridges are carried out using first order and second order reliability method (FORM and SORM). The probability of failure, p_f or the safety index, of the system respectively are the main results of the calculation procedure. This paper shows the approach and the application with an example. Particularly in the communal sector the method can be helpful, because it can not be assumed that in all cases the regular bridge inspections and the appropriate maintenance have been carried out.     

Rheinbrücke Breisach – Umbau und Instandsetzung einer 45 Jahre alten Stahlkonstruktion

The Rhine Bridge at Breisach – Alteration and maintenance work at a 45‐years‐old steel structure across the river Rhine. The Breisach Rhine Bridge between Breisach in Baden‐Württemberg, Germany, and Neuf‐Brisach in Alsace, France, is next to the Europe Bridge Kehl–Strasbourg the most important road connection between the two countries. The three‐pillar road bridge was built in 1962 using the foundation of an old railway bridge. The box girder of the bridge is welded as well as riveted and bolted. Both the design of the curb with its underseepage – a feature that was often used at that time but is now out of favour – and damages at the drain pipes in the girder box led to significant corrosion damage. In the future a bicycle lane will run over the bridge. For this an enlargement of the southern footpath is required. Bridge repair and maintenance work began in the spring of 2008. In this paper not only the details of the projects will be considered, but also the solutions to the problems discovered during repair work. An additional special feature of the bridge is the fact that two road construction agencies, one French, one German, are in charge of maintenance.     

Zur Weiterverwendung der Eisenbahnhochbrücke Hochdonn über den Nord‐Ostsee‐Kanal

Refurbishment of the railway bridge Hochdonn across the Ciel Canal. This paper gives details of the safety and residual life assessments for the railway bridge across the North‐Sea‐Baltic‐Sea‐canal at Hochdonn showing aspect of traffic development, pre‐damages and repair work and braking loads. The study shows that the structure though designed according to old specifications with simple calculation models that are compensated by adequate structural detailing complies basically with modern requirements for serviceability and ultimate limit states including durability if some additional measures are carried out to take modern standard‐developments into account.