Time-dependent changes in the instantaneous stiffness of reinforced concrete beams

摘要: Abstract The instantaneous stiffness of a reinforced concrete (RC) beam deteriorates with time and this fact may have important consequences for the long-term in-service behavior RC structures, particularly those that are subjected to repeated loads, vibrations or dynamic effects. There two main causes time-dependent deterioration stiffness. first is formation new primary cracks, both within outside original cracked region beam. second propagation fine cone-shaped cracks originate at steel-concrete interface mainly confined cover concrete. These cover-controlled facilitate reduction in bond manifested decay tension stiffening driven by combined effects shrinkage-induced tensile stress concrete’s strength under sustained (creep rupture). This paper presents an analytical model estimation beams particular focus on shown agree well recent experimental results.