Deformations of reinforced-concrete beam–column joint assemblies

Beam–column joints are generally recognised as critical regions in the analysis and design of moment-resisting reinforced-concrete (RC) frames subjected to both lateral and vertical loads. Such joints should be designed and detailed to ensure that they have adequate overstrength and allow adjacent beams to reach their full ductile capacities. To develop an improved method for predicting the deformation capacity of RC beam–column joint assemblies, the deformation contributions of structural members connecting the joint should be considered. A method is proposed to predict the deformation component ratios of RC beam–column joint assemblies that fail in shear after the adjacent beams have reached their full plastic capacities. The proposed method takes into account the effect of the longitudinal axial strain in the plastic hinge region of beams on the joint longitudinal strain and the strength deterioration of the joint. To verify the deformations of typical RC beam–column joint assemblies estimated using the proposed method, six specimens were tested. Furthermore, 35 experimental results of joints reported in the technical literature were compared with the deformations predicted by the proposed method. Comparisons between the observed and calculated deformations of the considered RC beam–column joint assemblies showed reasonable agreement.