Abstract
Deformability of welded frame-structures in buildings is greatly affected by mechanical properties, especially work-hardening behaviors of steels on deformability of welded frame-structures, bending tests of specimens having a column-beam connection (H-shape beam) were carried out. For these experiments SM41B steel, SM50B steel and two kinds of HT60 steels with the different yield to tensile ratio were used.
Main results obtained are summerized as follows.
(1) Local buckling occurs and develops first in flange and then in web of the H-shape beams under the bending load. The maximum plateau of load-deflection curve on the H-shape beam is attained after the local buckling in web. The maximum load depends on the geometry of the H-shape beam, and decreases as the width to thickness ratio increases.
(2) The maximum load value in H-shape beam is greatly affected by the tensile strength of steels used. Deflection at the load point and the absorbed energy of beam up to the maximum load, which are typical measures of the deformability of frame structures, depend on the yild to tensile ratio and uniform elongation (εT) of steels. Beams made of steels with lower yield to tensile ratio have larger deformability.
(3) In order to improve the deformability of beam using steels with small εT, it is effective to enlarge their εT.
(4) H-shape beam with scallop has a possibility of fracturing from the corner of the scallop.
