Author(s)

Y. Kimura & T. Ishihara

Abstract

Recently, the high tension steel with the yield stress of 800 kN/mm2 was developed, and the loading test of the structural members with this steel has been confirmed. It is shown that the ratio between ultimate strength and yield strength is almost unity, so that the members with this steel have quite small ductility. When rigid moment resisting frames with high tension steel are subjected to seismic force, the fracture at the ends of beam may occur and it causes the strength of frames to decrease. On the other hand, the semi-rigid moment resisting frames without diaphragm with high tension steel can absorb the seismic energy at the beam-to-column connections due to its plate bending deformation. This study performs cycle loading experiments to high tension steel part frames, and compares the initial rigidity and the yield strength of part frames without diaphragm with that of part frames with diaphragm. In addition, these experimental results are compared with the approximation of the reference. Keywords: high strength steel, fracture, plate bending deformation, ultimate strength, diaphragmless. 1 Introduction The new steel named H-SA700 has been developed to decrease the alloy element and to establish the streamlined process of heat treating in the project in Japan during 2004 and 2008. In the view of cost, it is better than the steel used with 800N/mm2. The main seismic frame with this new high strength steel has the possibility to keep elastic and the only damper becomes plastic, even though it is subjected to a large earthquake. On the other hand, it is shown that this new high strength steel has smaller fracture capacity and lower fatigue performance than the used steel of SS400 and SM490 with ultimate stress of 400N/mm2–

Keywords

high strength steel, fracture, plate bending deformation, ultimate strength, diaphragmless.