The authors have already proposed the concept of "Stable Limit" on the deformation capacity of columns in seismic design, from the viewpoint of energy absorption in columns, and have also presented the methods for evaluating the strains, curvature, and deformation at the stable limit. In order to verify the "Stable Limit" concept and the adequacy of the proposed method of evaluation, compression tests, bending tests, and shear bending tests of columns were conducted. The following findings can be drawn from these tests and their investigation. 1) Three moment versus curvature relations adequately correspond to each others ; one of them is given by the analysis of the critical section using the stress versus strain relation of the compression test, the other two are directly obtained from the bending test and the shear bending test, respectively. 2) In case of low axial stress, the columns under cyclic lateral loading are considered to behave almost same as the columns under monotonic loading ; the deformation capacity of the columns corresponds to the deformation at the stable limit, and the proposed method of evaluation is sufficiently accurate. 3) However, in the case of high axial stress, the cyclic loading history greatly affects the deformation capacity of the columns, and the proposed method of evaluation can not adequately predict the deformation capacity. The detailed verification of the method of evaluating the strains, etc. at the stable limit, a method of evaluating the deformation capacity of the columns under high axial stress level, and a reasonable design method for confinement in columns will be reported in the near future.
