This study suggests a semi-empirical model and an analytical model to predict the shear strength of reinforced concrete (RC) exterior beam-column joints without transverse reinforcement (denoted as unreinforced) in the joint region. A large experimental data set of unreinforced exterior beam-column joints from published literature is collected using consistent criteria. From the parametric study of the database, it is proved that the shear strength of unreinforced exterior beam-column joints is significantly influenced by two parameters: (1) the joint aspect ratio, and (2) the beam reinforcement index, which is related to the amount of longitudinal beam reinforcement. Two equations of each parameter are formulated by equilibrium and verified by comparison with the database. A semi-empirical model is developed using the derived equations of the two parameters. The proposed semi-empirical model shows high accuracy for predicting the joint shear strength, compared with other existing models. As another approach, the analytical model is developed based on the two in clined struts mechanism in a parallel system. The fraction of each diagonal strut is assumed based on the bond strength deterioration between the beam reinforcing bars and the surrounding concrete. The proposed analytical model is validated by comparison of its predictions with the test data of unreinforced exterior beam-column joints from published literature. The proposed analytical model is capable of predicting the two main types of joint failure, namely joint shear failure without and with yielding of beam longitudinal reinforcement, without using modification of the diagonal strut width and without the need for the estimation of a ductility factor. Furthermore, demonstration analyses of published tests are successfully performed using a representative rotational spring element for the beam-column joint based on the proposed analytical model. The proposed semi-empirical and analytical shear strength models of unreinforced exterior beam-column joints can be adopted to assess the seismic performance of existing RC bu ildings with deficient seismic details in the joint region.
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