STEEL BOX GIRDER BRIDGES

BOX GIRDERS ARE IDEAL FOR BRIDGES BECAUSE OF THEIR TORSIONAL RIGIDITY; HOWEVER, COGNIZANCE MUST BE TAKEN OF THE STRESSES RESULTING FROM THE TRANSFER OF FORCES IN THE BOX. THE DESIGN APPROACH SHOULD BE TO SELECT THE BOX SECTION BASED UPON THE CLASSICAL ELASTIC THEORY NEGLECTING THE EFFECTS OF SHEAR LAG AND DISTORTIONAL STRESSES, THEN TO SUPERIMPOSE THESE SECONDARY EFFECTS AND MODIFY THE SECTION WHERE AND IF NECESSARY. IN ADDITION TO DISCUSSING THE SPECIAL CONSIDERATIONS AND CAUSES OF FAILURE OF SOME BOX GIRDER BRIDGES, THIS ARTICLE TRACES THE DEVELOPMENT OF THIS TYPE OF BRIDGE USING EXAMPLES FROM THIS COUNTRY AND ABROAD AND REPORTS ON RECENT CONFERENCES ON BOX GIRDER BRIDGES. THE SHORTER SPAN HIGHWAY GRADE CROSSINGS USING STEEL BOX GIRDERS COMPOSITELY WITH A CONCRETE DECK ACCOUNT FOR THE GREATEST NUMBER OF THE STEEL BOX GIRDERS BUILT IN THE UNITED STATES. /AUTHOR/