Universal Mathematical Model for Predicting the Ductility of Reinforced Concrete

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The objective of this study is to establish the general computing method for accurately predicting the deformation and ductility of reinforced concrete members reversed cyclic loading. The Special attention was paid on the progress of fracture under cyclic loading and the progress of deformation and plasticity under sustained loading.1. Progress of fracture under cyclic loadingThe effect of cyclic loading on the stress transfer along cracks was investigated. It was clarified that shear stiffness along cracks is greatly reduced under initial reversed cyclic loading.2. Progress of deformation under sustained loading.The effect of sustained loading on the tension stiffness in the normal direction to cracks was investigated. Time-dependent behavior of tension stiffness was clarified after yielding of reinforcing bars.3. Modification of analytical systemUsing the constitutive equations developed under cyclic-and sustained. loading general constitutive equation was introduced to the analytical system. Time-dependent and path-dependent constitutive model was developed and dynamic analysis for reinforced concrete was succesively carried out.4. Development of Joint elementThe effect of cyclic and sustained loading on the bond behavior steel bar and concrete was investigated. Modified joint element was proposed with high applicability and high accuracy.