Abstract
Load-Deflection characteristics of H-shaped steel beams built up by welding as designed on the basis of the current allowable stress design specification were studied. In this experiment 14 pairs of portal frame connected with side beams were used. The behavior of the parallel main beams were observed up to their collapse state. Dimensions of main beams covered large variety of sectional shapes, slenderness and supporting conditions. In these specimens the width-to-thickness ratios of the web lied between 45 and 80, and the slenderness of the flange lied between 100 and 200. The result of the test is summarized as the followings. (1) The deformation capacity of beams restrained only by sub beams ranged from 1.0 to 2.3. (2) The deformation capacity of beams restrained only by slabs ranged from 1.5 to 3.5. (3) The deformation capacity was fairly improved by stiffening web against local buckling. Especially combined with restraint by slabs, the stiffening effect was considerable, and the deformation capacity could reach about 4.0. (4) Effects of end fixity provided by side beams on load-deflection characteristics was not obvious, and it was observed that even hinged connection of side beams can provide fairly large restraint on the stability of the main beam.
