Abstract
This paper presents an estimation method for the experienced maximum load and displacement response by small load increment. The proposed method is based on the correlation between the initial secant stiffness of a damaged column by small load increment and the equivalent secant stiffness of the maximum response experienced. Nine reinforced concrete square column specimens were tested under static reversed cyclic loading. The variables were the loading direction, the pitch of the confining steel and the magnitude of the small load increment. The test results indicated that the relationship between the secant stiffness under small load increment and the equivalent secant stiffness corresponding to the maximum experienced response was represented by a logarithmic function. Also, the relationship between the displacement caused by small load increment and the experienced maximum displacement of the damaged columns was expressed by an exponential function. From these test results the applicability of the proposed method was examined. However, further experimental and analytical studies are needed to obtain a more reliable estimation method.
