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Gelsenkirchen, Germany

Schmidt A.,SCHACHTBAU NORDHAUSEN GmbH | Weissbrich M.,W and S Ingenieure | Hagemann A.,ANKER SCHROEDER.DE ASDO GmbH | Hamme M.,Landesbetrieb Strassenbau NRW
Stahlbau | Year: 2013

The replacement of the Bridge Schnettkerbrücke started with the assignment of the construction company Schachtbau Nordhausen GmbH in September 2005. It was quickly to realize, that the building of this technical and optical ambitious bridge was a great challenge for all participants. The erection had to take place under diffi cult conditions. The disturbance of road and railroad traffi c must be reduced to a minimum. The building of the foundations was very diffi cult. Besides of the building of the new bridge the old bridge must be deconstructed. The interests of the inhabitants of the urban district Schönau had to be respected, because they were disturbed by the site traffi c during the whole construction period. The following paper describes the technical solutions to execute the complex construction process. For a general description of the bridge see [1]. Source


Current requirements for assessing fatigue behavior in existing prestressed concrete bridges include determining the bridges built-in steel tendons fatigue strength. Standardized S-N curves are normally used for fatigue design in new bridges, which display the tendons' fatigue strength in relation to the number of load cycles under a specific stress range. However, because older design requirements for road bridges did not demand fatigue design, specific curves for older steel types are not available. Yet the structural health of older road bridges must be assessed to determine their safety and viability of further usage. Therefore, the research presented here was undertaken to determine whether standardized S-N curves could be applied to the older prestressing steel found in older road bridges. For this testing, it was determined that some prestressing steel patterns might be reclaimed from an older bridge along the German Autobahn A1 south of the city of Dortmund (Bridge # 67, called Station Westhofen, built in 1957) during the bridge's demolition. Because the steel tendons of this old bridge were not entirely covered by concrete due to bonding failure, some strands were easily obtained. These tendons did not display any signs of damage or indications of pre-damage caused by fatigue. Interestingly, the strands' surfaces showed only traces of rust, which were removed carefully before the tests were begun. Overall, five concrete beams with curved ducts for the steel tendons, which were prestressed with the reclaimed strands, were subjected to fatigue loads. Varied stress ranges were used in order to obtain a full S-N curve for the older steel. The results of these tests were then compared to standardized S-N curves for current prestessing steel. These comparisons indicate that older prestressing steel fulfills the present fatigue requirements so that current standardized S-N curves may also be used to assess the fatigue strength of older steel tendons. Source


Mauer S.,Ingenieurburo Grassl GmbH | Rockenfelder R.,Landesbetrieb Strassenbau NRW
Beton- und Stahlbetonbau | Year: 2013

In the course of the six-lane extension of the A1 motorway, the existing viaduct Einsiedelstein had to be partially renovated. It is an vault bridge built in 1938. As a basis for the planning of necessary measures of redevelopments finite element calculations were carried out taking into account the non-linear material behavior of the backfill concrete and masonry vaults for the loads of DIN technical report. The applied calculation methods allow a realistic modeling of the load-bearing behavior of historic masonry structures in the ultimate limit state and serviceability limit state. The calculation results were used for choosing a sustainable measure for the partial replacement of the vault bridge. Copyright © 2013 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Source


Schafer R.,Dr. Spang GmbH | Spang C.,Dr. Spang GmbH | Timmermann V.,Landesbetrieb Strassenbau NRW
Bautechnik | Year: 2013

For a structural support of a counter bearing of a roadway bridge across the Agger-valley, 14 permanent grouted anchors were installed at the end of the 1970s. In the course of the last bridge inspection it was found, that one of the two installed load cells measuring the anchors forces did not show any data. As a consequence, reloading measurements of the anchors were initialized in order to determine the actual forces of all anchors. The results of the measurement show, that a load transfer from the inner to the outer anchors had taken place leading to lower anchor forces in the inner area and greater anchor forces at the boundary in comparison to the calculated pre-stressing force. Accordingly, the two outer anchors are close to the ultimate limit state. The results of the reloading measurements are evaluated with reference to the global safety concept according to DIN 4125:1990 and the partial safety concept according to EC 7-1. It can be shown, that the distinguished approach of the safety factors for the loadings may be advantageous for the design of the anchors. However, the example shows, that questions remain concerning the inspection of permanent grouted anchors, which © 2013 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Source


While analysing current traffic volume on German highways, an exceedance of the planned bearing capacity for most of the highway bridges was detected. This exceedance is mainly caused by increasing daily traffic volume, including increasingly heavy trucks with a rising number of axes and load size. In fact, strengthening of most of these bridges becomes necessary to ensure future long-term serviceability of the German Autobahn system. In the meantime, first experiences in terms of structural assessment and strengthening of older highway bridges were collected. Therefore, this report presents gained experiences concerning the refurbishment of more than 250 older highway bridges. Furthermore, recommendations for application, interpretation and evolution of technical regulations are given. For these purposes process steps, methods of choice and technical solutions are described. © Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG. Source

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