Shigeaki Tohnai

Shear Resistance Mechanisms on Steel Sheet Shear Walls with Burring Holes and the Effect of Cross-Rails

Steel sheet shear walls are panels in which sheets with burring holes aligned along the vertical direction are fastened to frame members and are applied to multi-story buildings in seismic regions. The wall that receives the in-plane shear force allows shear stress to concentrate in intervals between the burring holes. Finite element analyses and in-plane shear experiments revealed that all intervals between the holes were simultaneously deformed, and buckling areas were limited in the intervals by ring-shaped ribs of the burring holes. The effects of cross-rails are minimal in elastic region. Post-buckling behavior depends on tension fields on the intervals and restraints by cross-rails. The allowable design strength formulas and the indices of strength after buckling are developed.

Interaction between Over-Turning Moment and Shear Capacity of Seismic Light Gage Bearing Wall

Light gage structure, where the plate thickness is less than 2.3mm, is limited up to three story buildings in Japan. This type of structure is used mainly on residential and commercial buildings. Seismic force is one of the most important design factor; light gage bearing wall is usually used for the horizontal force resisting component. Light gage bearing wall is composed with light gage frame and structural laminated plywood or gypsum board. Usually, over-turning moment due to lateral force is negligible in low rise building; however, it is questionable to adapt the same theory in middle rise building. To clarify the effect of over-turning moment to the bearing wall on light gage structure, full scale testing was conducted in this study. From the full scale testing, following results were found. (1) Over-turning moment was mainly resisted by the couple forces of the stud; horizontal force was mainly resisted by screws which are connecting plywood or gypsum board to the light gage frame. (2) Effect to over-turning moment to the shear capacity was observed when the magnitude of the moment exceeded 50% of its capacity.