In a structurally non-uniform building comprising a lower part by SRC construction and an upper part by RC construction, generally columns of a floor where the structure type changes from SRC construction to RC construction are subject to a large fluctuating axial force and a large shear force. Therefore, structural performance under a high axial force (compression, tension) is important. However, no structural test has been made under these conditions so far. Thus, we confirmed the following through two series of tests under a fluctuating axial force: 1. A sufficient anchorage can be secured when the maximum strain of special lateral reinforcement far exceeds the yield strain, the special lateral reinforcement pierces web plates, and an overlap length of 10d is secured. 2. Under a compressive axial force, special lateral reinforcement is effective for binding concrete and useful for preventing the buckling of main reinforcement. And, under a tensile axial force, it increases the anchorage of cut-off bars. 3. Crest plates are effective for displaying the maximum strength and for controlling a degradation in strength after the maximum strength. 4. Under a compressive axial force, the flexural yield strength of SRC-RC switching columns reaches the generalized cumulative strength of SRC columns. 5. Under a tensile axial force, too, the flexural yield strength of SRC-RC switching columns reaches the generalized superposed strength of SRC columns by making the length of the projected steel frame close to the inflection point height. From the above, the yield strength deformation performance of SRC-RC switching columns under high compression and high tension can be secured by a reinforcement method using special lateral reinforcement and crest plate.
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