Tatsuya Nakano

Cyclic Behavior of Panel Zone in Steel Moment Frame under Bidirectional Loading

This paper aims to examine the cyclic behavior of panels in steel moment frame subjected to bidirectional and unidirectional loading and to demonstrate the differences of panel behavior under two loading modes. The specimens were composed of wide-flange beams and square tube columns, and the panel zones were designed to yield before columns and beams. Experimental results showed that specimens subjected to bidirectional loading suffered severe damage, caused by the weld fracture at the corner of panel-to-diaphragm weld, and failed at 0.06 rad and 0.04 rad story drift for specimens with panel aspect ratio of 1.4 and 2.0, respectively. Specimens subjected to unidirectional loading developed a story drift of 0.06 rad without strength reduction. The panels contributed about 60%-80% story drift and dissipated approximately 80% of total input energy. Panels with higher aspect ratio showed smaller plastic shear strength because of the effect of flexural yielding in panels. Moreover, the beams were found to present plastic moments 20%-50% lower than theoretical values, which was attributed to the small panel-to-beam strength ratio.

STRUCTURAL DAMAGE ON SCHOOL GYMNASIUMS DUE TO THE 2011 TOHOKU EARTHQUAKE

In order to clarify structural damage on school gymnasiums due to the 2011 Tohoku Earthquake, total 1611 of school gymnasiums in Iwate Prefecture, Miyagi Prefecture, Fukushima Prefecture, Ibaraki Prefecture, and Tochigi Prefecture were investigated. More than 70% of investigated school gymnasium were slightly damaged or not damaged. On the other hand, about 6% of school gymnasium built in or after 1982 were seriously damaged. Moreover, in this paper, structural elements damaged seriously in the school gymnasiums built in 1982 or afterwards were examined.