せん断挙動が支配的な鉄筋コンクリート造耐震壁の水平二方向加力実験 [in Japanese] BI-DIRECTIONAL LATERAL LOADING TESTS ON RC SHEAR-DOMINANT WALLS [in Japanese]
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Shear walls deform not only in in-plane direction but also in out-of-plane direction by earthquake ground motions. Little experimental data of structural wall failing in shear are available on the influence of out-of-plane deformation on in-plane seismic resistance. Structural performance of shear walls such as load carrying capacity and deformability has not yet fully been investigated when they deform in its out-of-plane direction along with in-plane direction. Shear capacity reduction by bi-directional loading is expected, but in practical design it is not taken into account. The objective of this study is to investigate the influence of out-of-plane deformation on in-plane shear resistance of wall failing in shear. The paper reports bi-directional cyclic loading tests carried out by the authors. The test results will contribute to establishment of design methods.<br><br> Three 1/3-scale reinforced concrete shear walls were constructed. The specimens were composed of a wall panel and two boundary columns. Their cross sections and reinforcement arrangement were the same in all the specimens. They were designed to fail in shear prior to flexural yielding in in-plane direction, and to fail in flexure in out-of-plane direction prior to shear failure. They were tested under bi-directional cyclic lateral loading simulating earthquake ground motions and the vertical load 840kN was also applied as service load. The test variable was the ratio of out-of-plane to in-plane deformations, which was 0, 1.5 or 3.<br><br> Out-of-plane deformation caused flexure cracks in wall panels and concrete crashing by compression at the corner of the boundary columns. All the specimens reached their maximum load carrying capacity at the inter-story drift of 0.5% or 0.75%. The maximum lateral loads of the specimens subjected to bi-directional loading were approximately 8-18% less than that of the specimen subjected to uni-directional loading. Shear deformation was about 80% of the total in-plane horizontal deformation in all the specimens.<br><br> An estimation method for shear capacity of shear walls under bi-directional loading was proposed. The interaction between lateral load capacities in the in-plane and the out-of-plane directions takes the form of two concentric ellipses. One is an ellipse denoting flexural yielding and the other is the one for shear failure. The maximum load resistances of walls subjected to bi-directional loading are schematically shown as the inscribed curve bounded by the two ellipses.
- Journal of Structural and Construction Engineering (Transactions of AIJ)
Journal of Structural and Construction Engineering (Transactions of AIJ) 82(735), 683-692, 2017
Architectural Institute of Japan