The Shear Strength of Reinforced Concrete Beam-Column Joints

Beam-column joints were subjected to deformation to establish basic shear behavior. Fourteen interior type connections with reiforcing bars continous through the joint were tested. The effects of column reinforcement, column load, joint hoop reinforcement, lateral beams, concrete strength, the ratio of the depth of the column to the depth of the main flexural member, and load reverals on the shearing strength of the beam-column joint were investigated. Specimens were designed using the recommendation of ACI-ASCE Committee 352 and were proportioned so that shear stress in the joint would determine the maximum loads rather than yielding of the flexural members. The failure mode of eac specimen was observed. From statistical analysis of the test data and the mode of failure, new design recommendations for basic shear strength are made theat deemphasize column load, concrete shear cracking, and joint hoop reinforcement, and emphasize concrete strength. Based on the load reversal tests, a modification to the basic shear strength is proposed to account for shear strength degradation under cyclic load. The form of the proposed design equation is substantially different from the current ACI-ASCE Committee 352 recommended practice. The proposed design approach represents a significant advance in the understanding of the shear behavior of the beam-column joint.