Self-launching erection machines for precast concrete bridges

摘要

>Launching units are complex and delicate structures. They resist high loads on long spans under the same constraints that the obstruction to overpass exerts onto the final structure. They are adaptable for reuse on different projects. They must be as light as possible, which involves designing for high stress levels in different load and support conditions, and they are assembled and dismantled many times and reused by different crews. For all of these reasons, self-launching bridge erection machines are typically purchased or leased based on purpose-written technical specifications, their design is subjected to independent checking, load testing is frequent at the end of assembly, and the operations are ruled by written procedures. Little has been written on these machines in spite of their cost, complexity, and sophistication. This article illustrates the main features of self-launching bridgeerection machines and includes some lessons learned.>References>1. Rosignoli, M. 2002.target="_blank" title=" Bridge Launching" href="http://dx.doi.org/10.1680/bl.31463 "> Bridge Launching. London, UK: Thomas Telford. >2. American Segmental Bridge Institute (ASBI). 2008. Construction Practices Handbook for Concrete Segmental and Cable-Supported Bridges. Phoenix, AZ:  ASBI.>3. Hewson, N. 2003. target="_blank" title="Prestressed Concrete Bridges: Design and Construction" href="http://dx.doi.org/10.1680/pcbdac.32231 ">Prestressed Concrete Bridges: Design and Construction. London, U.K.: Thomas Telford. >4. Federation Europeenne de la Manutention FEM 1.001. 1987. R?¨gles pour le Calcul des Appareils de Levage. [In French.] >5. CNR 10021. 1985. Strutture di Acciaio per Apparecchi di Sollevamento. Istruzioni per il Calcolo, la€?Esecuzione, il Collaudo e la Manutenzione. [In Italian.] >6. Rosignoli, M. 2007. target="_blank" title="Robustness and Stability of Launching Gantries and Movable Shuttering Systems - Lessons Learned" href="http://dx.doi.org/10.2749/101686607780680673 ">Robustness and Stability of Launching Gantries and Movable Shuttering Systems - Lessons Learned. Structural Engineering International, 02/2007: pp. 133-140.