Study on Servceability Limit States of Reinforced Concrete Structure

点击翻译按钮获取中文摘要

1. Under Sustained Loading(1) Relation between bond stress and slip of reinforcement in concrete under sustained loading was understood. (2) Additional deflection due to slip of reinforcement from anchor zone was larger than flexural deflection on cantilever beam. The slip of reinforcement could be predicted by use of proposed bond stress - slip model. (3) Delay of loading time after prestress transfer resulted in increase of long-term crack width and decrease of long-term deflections. (4) Crack width could be predicted by the proposed method. The ACI method for predicting deflections underestimated long-term deflections in beams.2. Under Repeated LoadingReinforced concrete beams and partially prestressed concrete beams were repeatedly loaded for 20 or 200000 cycles at two load levels which correspond to 1000 and 2000 kgf/cm^2 of steel stress. The results obtained were as follow : (1) Increase in crack width and deflections under repeated loading after 2 or 3 cycles was extremely little at the lower load level. At the higher load level, however, deformations increase linearly with number of cycle on a semi-loga scale. (2) Increase of deformation due to repeated load was caused by relaxation of bond stress and increase of compression strain of concrete.