Reinforcement Detailing for Local Cracking

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A crack in concrete dominant in lightly reinforced area tends to develop unstably and progressively in cases of beams subjected to shear, temperature change and drying shrinkage of slabs and walls, or anchor pull-out. Methods are not established for computation to predict propagation of such cracks, and consequently, theory is insufficient for reinforcement detailing.A method for computational simulations were developed for application to various behaviors using an assumption that a criteria for crack propagation is determined by stress intensity factors of linear fracture mechanics, and using finite element analysis.The method was found to be reasonably capable of simulating propagations of cracks in cases of : diagonal tension cracking in beams subjected to shear, cracking in anchor pull-out, and discrete cracking in slabs due to shrinkage where reinforcement restrained crack opening to a certain degree.Characteristic values for the stress intensity factors for propagating cracks are not established for each behaviors studied. Because of that, accuracies are not satisfactory in predicting external loads to propagate cracks at various stages up to strubtural failure. The method was found helpful for predicting distribution and paths of crack developments for the cases studied. Thus the method was deemed helpful for detailing reinforcement.