Abstract
Cantilever-type reinforced concrete column specimens are used for uniaxial and biaxial static lateral loading tests. Specimens are approximately full scale models considered to be representative of the first story interior columns in typical three to five storied buildings in Japan. The behavior of cracking and spalling of the reinforced concrete columns specimens under, the action of biaxial loading could simulate somewhat the earthquake damage features of frame-type RC buildings observed in the past strong earthquakes. The biaxial loading gives more serious damage to the concrete columns than the uniaxial one. According to the crack-spall off damage index, discussed in this study, (1) If the crack length ratio is around 10 and the spall off area ratio is from 10 to 30 %, the maximum ductility should be around 3. (2) If the spall ratio is more than 50 % and transverse bars become loose and longitudinal bars buckle, the maximum ductility should be more than 5.
