FAILURE TESTS OF MODEL STEEL BOX GIRDERS

MODEL TESTS WERE SUCCESSFULLY UTILIZED TO OBTAIN INFORMATION ON THE BEHAVIOR, MODES OF FAILURE, AND LOAD-CARRYING CAPACITY OF SINGLE SPAN RECTANGULAR STEEL BOX GIRDERS. THIS STUDY, WHICH INVOLVED THE TESTING OF TWO SLENDER-WEB STEEL MODEL BOX GIRDERS UNDER DIFFERENT COMBINATIONS OF BENDING, SHEAR, AND TORSION, PROVIDES INSIGHT INTO THE POST-BUCKLING BEHAVIOR OF SUCH MEMBERS. THE TEST SPECIMENS WERE DESIGNED TO SIMULATE BOX GIRDER BRIDGE MEMBERS HAVING A CONCRETE OR ORTHOTROPIC STEEL DECK. WHEN SUBJECTED TO ONLY SHEAR AND BENDING, THE SPECIMEN EXHIBITED A BEHAVIOR QUITE LIKE THAT OF SLENDER-WEB PLATE GIRDERS UNDER SIMILAR LOADING CONDITIONS. THE ADDITION OF TORSION HAD A SIGNIFICANT EFFECT ON THE BEHAVIOR OF THE SPECIMENS. FOR ALL CONDITIONS OF LOADING THE SPECIMENS DISPLAYED DEFINITE STRESS REDISTRIBUTION CAPABILITIES AND CONSIDERABLE POST-BUCKLING STRENGTH. FAILURE MODES WERE CHARACTERIZED BY TENSION FIELD YIELDING OF THE WEBS AND OUT-OF PLANE DEFORMATIONS OF THE FLANGES.