DEVELOPMENT OF HIGH-PERFORMANCE STEEL FOR STEEL BUILDINGS

In the ultimate limit state design and seismic design of steel structures it is postulated that the structural members have sufficient deformability or rotation capacity. In this context, the relationship of the plastic deformation capacity of steel structural members and the stress-strain curves of their materials are clarified. To secure sufficient deformation capacity of structural members, the yield-ratio (the ratio of yield stress to tensile strength) should be reasonably low. For flexural members such as beams and beam-columns, the rotation capacity can be evaluated by the complementary energy of materials. Scattering of yield stress could give an adverse effect on the strength and deformability of steel structures subject to horizontal loading. From this viewpoint, the upper limits of the yield stress and yield ratio should be specified in the material standard.