Abstract
The restoreing force characteristics of reinforced concrete elements based on the various tests results are presented considering the decrease of overall stiffness of the hysteresis loop according to the increase of the deformation. The force-deflection curve having the above characteristics is modelized by the N. C. L. Model composed of "Skeleton Curve" and "Normalized Characteristic Loop". Random hysteresis and its characteristics are shown in connection with the steady-state hystersis loop. Various factors which influence on the hysteresis such as element section, steel bar section, axial force of columns are to be presented in next paper. The static analysis of hysteresis based on the stress-strain relationship of materials, and dynamic analysis using the N. C. L. Model will follow.
