Concrete Bridges in Germany
This article gives an overview over the state of th e art of concrete bridges in Germany. In addition t o the presentation of actual bridges projects (e.g. winners of German bri dge award) new trends in bridge construction and po st-tensioning technology will be presented. One is prestressing b y combining unbonded internal and external tendons which already had been realized at the pilot-projects Mühlenbergb rid e and Roßriether Graben-Bridge. Furthermore, th development and actual state of standards for the design concre te b idges are shown. At the moment the design is d one according to the German code DIN-Fachbericht 102 “Betonbrücken”.
ASSESSMENT OF INTERNAL AND EXTERNAL PRESTRESSING OF PRESTRESSED BOX GIRDERS
AbstractBridges have been built since many years also box girder bridges are being constructed since the 1920s. Initially, only mild steel reinforced box girder bridges were used. But as the requirement of long spans box girders with minimum depths was arising, the use of high strength prestressing steel in the construction of box girders was started. The major work for prestressing or post-tensioning was done by Freyssinet (for internal prestressing). The use of external post-tensioning was evolved in the 1930s in Germany initially. External prestressing had been abandoned in late 1960's and early 1970’s, because of several drawbacks, the main one was corrosion of steel. The strengthening capabilities of external tendons became the reason for its reintroduction in late 1970’s. In this study, an effort is done to briefly explain the procedure for the design of box girders with internal and external prestressing systems. Also, the cost of the two systems is compared for different spans considering stress limitations and serviceability criteria. This has been done by modeling box girders with spans ranges from 30m to 90m and for the span to depth ratios of 15, 20 and 25. In general, this study quantitatively indicates the prestressing force required for the two systems.
PLATTEN. PLATTENSTREIFEN - PUNKTGESTUETZTE PLATTEN - ZWEI-, DREI- UND VIERSEITIG GESTUETZTE PLATTEN - DREIECKPLATTEN - KREISPLATTEN - DRILLWEICHE PLATTEN, PLATTEN MIT UNTERBROCHENER STUETZUNG - PLATTEN AUF ELASTISCHER BETTUNG. 2. AUFLAGE
DIE UNTERSUCHUNGEN SIND AUF SELTENER VORKOMMENDE PLATTENTYPEN UND UNBEKANNTERE LITERATUR AUSGEDEHNT UND EDV-BEARBEITET. ANMERKUNGEN ZUM BERECHNUNGSVERFAHREN, BEMESSUNG BEI VON DEN HAUPTMOMENTENRICHTUNGEN ABWEICHENDEN ORTHOGONALEN BEWEHRUNGSNETZEN UND ELF EINZELNE PLATTENTYPEN SIND ANGEFUEHRT. DIE MITWIRKENDE PLATTENBREITE VON PLATTENBALKEN UND EBENSOLCHE LASTBREITE VON DECKENPARALLEL SPANNENDEN BALKEN (STREICHLAST), ANGEHAENGTE KRAGPLATTEN UND DAS SUPERPOSITIONSPRINZIP BEI PLATTENTRAGWERKEN SIND AUSFUEHRLICH BESPROCHEN. 16 BERECHNUNGSBEISPIELE HABEN LEHRWERT. (A*).