付着のない鉄骨コンクリート柱の曲げ耐力について

抄録

Generally, the bending strength of concrete encased steel columns is calculated by the superposed strength method. It is known that values calculated by this method agree with experimental results and also with the values by Bernoulli-Euler's assumption. But, bond between steel and concrete is not complete, specially, it is often vanished under cyclic load. Even if such a case, values predicted by generalized superposed strength method agree with experimental results. In this paper, consideration on the mechanism of bending strength of concrete encased steel columns without bond is done and main conclusions are as follows ; (1) If strain capacity of concrete is sufficiently large, columns can reach the strength by generalized superposed strength method, whether bond exsists or not. (2) When strain capacity of concrete is not large, they cannot reach the strength by generalized superposed strength method. The reasons are grouped into 3 types. Type I : Each part of steel and concrete can reach its strength, but cannot reach the point realizing the generalized superposed strength. Type II : Steel part cannot reach its strength. TypeIII : Combination of Type I and II.