This paper investigated the effect of natural period ratio of RC frame to steel roof on seismic response of steel roof construction with brim-slab installed with friction dampers. A modeling of the school gymnasium was adequately carried out for a three-dimensional inelastic response analysis. The seismic responses of the gymnasia with different natural period ratios caused by the changes of steel roofs and brim-slabs were investigated. The damage to the frames of these models were analyzed and the dissipated energy ratio of the friction dampers to earthquake input energy were also shown in this paper. Finally, it was clarified that the natural period ratio was effective for the seismic design of such gymnasia.

We have developed a beam-to-column connection which has small projection exterior diaphragms using thicker steel plates than the conventional ones. This study aims to propose a rational design procedure for a steel moment-resisting frame (MRF) with exterior diaphragms. The design procedure focuses on the reduction rate of story stiffness of MRF with exterior diaphragms to that with rigid connections. The recommended optimum value of the reduction rate of story stiffness is proposed by static incremental analysis and time history response analysis.

This study estimates the collapse mechanism of an experiment that reproduces the destruction case of a steel open sabo dam using distinct element method (so called, DEM). In the experiment, a steel pipe open sabo dam was destroyed by a debris flow in Nagiso Town, and an steel pipe open sabo dam modeled in concerning with compressed deformation occurred is made of Barsa material. As a result, the compressed deformation occurred and the dam is damaged when the height of the preceding sedimentary gravel is 30 %. DEM analysis revealed that the axial force of the upper horizontal member increased in case of 30 % height of the preceding sedimentary gravels. Then the upper support diagonal member were broken due to bending force.

As a reinforcing method for orthotropic steel decks, the U-rib cutting method has been proposed, in which the welding area between the U-rib and the deck plate is cut and reinforcing plate is installed. However, due to the U-rib cutting, the stress concentration may occur at the deck-transverse rib welds. In this study, two intersection structures were applied to the full-scale test model. Moreover, the static and cyclic loading test was carried out. As a result, in the case of the intersection structure with reinforcing plate on the transverse rib, cracks occurred at the deck-transverse rib welds. For the intersection structure without the plate on the transverse rib, stress concentration occurred at the deck-transverse rib welds, but no fatigue cracks occurred.

In recent years, in the design of high-rise steel-framed buildings in Japan, a passive controlled structure that adds dampers is often used to reduce the building response in the event of an earthquake. There is room for consideration as to finding an effective damper arrangement. The previous report proposed a more effective velocity-dependent damper arrangement method (frame systems that amplify the effective deformation). However, this study corresponds to the result of arranging the same dampers on all the structural surfaces of the framework in which the same plane frames are parallel. This study discussed the relation between the number of applied frame systems amplifying the effective deformation and the response reduction effect. Furthermore, the effect of orthogonal frames was examined.

This paper investigated about the ultimate bending moment for corroded steel sheet pile. At first, we examined the corrosion shape of constructed steel sheet pile, and we idealized the corrosion shape based on these results. Secondly, we performed experiments and numerical analysis for steel sheet piles with partial plate thickness decrease. Finally, we propose the ultimate bending moment for corroded steel sheet pile.