TIME-DEPENDENT SHORTENING OF SLENDER RC COLUMNS

The paper presents a method of analysis for the short-term and time-dependent response of slender, reinforced concrete columns using the age-adjusted effective modulus method. For the long-term case, a recommended general numerical procedure used in a computer program is described in detail, The distributions of strain and stress on cross sections and the prediction of lateral deflection are given under both short-term and long-term (one-time-step and multiple-time-step case) situations. The formula for calculating column shortening is derived based on the principle of virtual forces. The method is applied to determine the axial and bending shortening of a pin-ended, isolated column. shortening-time-relation curves show the effects of axial and bending shortening on the total shortening respectively. The influence of eccentricity and column length on shortening are also studied. The results from the computer program are in good agreement with experimental and theoretical results reported by other investigators.