非対称2軸偏心荷重を受ける鉄筋コンクリート長柱の弾塑性挙動

Abstract

The elastic-plastic behavior of slender reinforced concrete columns with unsymmetricallybiaxial eccentricity of loading is investigated. The ultimate loads, transverse deformationsand the behavior up to failure of the columns are examined in detail experimentally andanalytically. Eight pin-ended column specimens with square cross section were tested. Theratio of column length to minimum depth of all specimens was 25. Load was appliedmonotonically at each column end with equal eccentricity of the opposite sign or unequaleccentricity of the same sign, at various angles from principal axis of the cross section. Whenthe columns are subjected to biaxially eccentric load to cause bending about the near-strongaxis, they have a tendency to deflect to bent about the weak axis of the section after theattainment of the maximum load. The columns loaded with equal eccentricity of the oppositesign show that their load carrying capacities suddenly decrease because of rapidly changingthe column deflection shapes from double-curvature mode to single-curvature mode near themaximum load. The numerical analysis to solve the load-deflection response of the columnpredicts the test behavior very well, taking into account the initial imperfection of eccentricityof loading at the column ends.