Experimental Study on the U-Shaped Steel Box Girders Using 1/4 Scale Test Specimen-II: Torsional Behavior

The objective of the present study is to understand the lateral torsional buckling behavior of the U-type girder system by structural tests and by the finite element analysis before it is combined with concrete slab. The pure torsional test also indicates that the W-type bracing system is more efficient in torsional resistance than the X-type bracing system. The equivalent plate thickness of the upper flange and the torsional stiffness of the U-shaped girder obtained by the finite element analysis compares well with those by the pure torsion test, which implies that the finite element method can be applied to obtain the equivalent plate thickness without performing rather expensive structural tests in the design stage of U-shaped girder system.