抄録
This paper theoretically evaluates the deformation capacity of R/C columns which fail due to the crush of concrete after flexural yielding. The following findings were drawn from this study. 1) In the process from yielding to failure, a stable limit appears from the point of view of energy absorption of columns. This stable limit corresponds to the limit of the extension of tensile longitudinal reinforcing bars. Before the stable limit, the columns show stable load-deflection curves. After that, the external energy associated with the axial force rapidly increases and the internal energy absorbed by concrete dramatically increases, then the lateral load carrying capacity drastically decreases. 2) The strain of the extreme compressive concrete fiber in the critical section at the stable limit is obtained from Eq. (29) expressed in terms of the stress versus strain relations for concrete and steel, and the axial stress level. Then, the strain in the tensile bars, the curvature, and the depth of the neutral axis are easily obtained. 3) The deformation mechanism of columns beyond flexural yielding can be represented by the truss model proposed in this paper. The tension strain distribution along the height in the hinge region obtained from this truss model was in excellent agreement with the strain distributions measured in the test. 4) The drift angle of columns at the stable limit can be calculated by Eq. (50), using the value of the strain in the tensile bars and the depth of the neutral axis in the critical section at the stable limit.
