ABSTRACT
ABSTRACT: In France, the incremental launching by sliding or rolling is the most common method for erecting steel bridges. Nowadays it is usual to launch steel I-girders of a twin girder bridge (span up to 120 m long) or box girders (170 m long span in Millau viaduct). The transverse load is applied through the lower flange over a long length, and the web buckling under patch loading may govern the design of the steel structure. Such long spans need steel webs up to 4 or 5 m deep that are usually longitudinally stiffened. In France, longitudinal stiffeners of twin-girder bridges are mainly discontinuous and made of single flat plates.
