Investigations on the Efficiency of Welded Strap

Abstract

In order to investigate the relation between the efficiency of the strap, the length of strap and the kinds of load, the authors performed bending tests on box girders which were reinforced with straps.
Five kinds of test specimens were used : a box girder itself and four box girders with box-fillet welded straps of which breadth (B=60 mm) and thickness (T=10 mm) were kept constant and length varied (L=60, 120, 200 and 300 mm).
Through the wire strain gage measurement, they obtained the stress distribution of strap, and then mean stress of strap. The efficiency of strap, ratio of the mean stress of strap to the value calculated by the beam theory increased rapidly with L, reaching 80% at L=200 mm (about 3.3 times breadth), and beyond this limit practically became saturated, showing little further increase. Difference of the efficiency was little regardless of the position of the attaching plane.
The theoretically calculated stress of strap showed the same inclination as the measured one.