Measurement System of Low Cycle Fatigue Parameters Applicable to Large Scale Structural Members

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This study aimed at development of measurement system of low cycle fatigue parameters applicapble to large-scale structural specimens. As a first step, strain measurement system based on image analysys and stereography was newly developed, because the main parameter for estimating low cycle fatigue strength was plastic strain in material. This newly developed system made it possible to measure large strain field of a structural member even if three-dimensiccnal deformation like buckling deformation occurred, which couldn't be measured by conventional method like strain gauge ethod. The procedures to detemine the correlation between two images and trace the targets points could be performed automatically, and the strain results could be obtained in a few seconds. This system was applied to loading test carried out on concrete filled steel tube specimen in large scale. By this system, crack initiation and propagation behaviors where the most critical damage occurred in the specimen could be estimated. In addition, the effects of dimensions of the member and loading conditions on local strain field could also be estimated.