Prediction of Strength and Shear Distortion in R/C Beam-Column Joints
G. J. Parra-Montesinos and J. K. Wight
Appears on pages(s):
beam-column joints; deformation; earthquake-resistant
structures; principal strains; reinforced concrete; shear distortion;
The behavior of beam-column connections in WC frame structures has been extensively studied since the 1960’s. These studies have served as the basis for design guidelines for WC joints, in which detailing requirements and stress limits are given to control damage and deterioration of strength and stiffness in the connections. However, no particular attention is paid to the deformation in the joint region and its relation to the connection strength. In this paper a model is presented to evaluate the shear strength of WC joints for various levels of joint shear distortion. The joint model is based on the state of plane strains in the connection through the development of a ratio between the joint principal strains, which was determined from experimental results. Based on the joint model, stress limits are proposed for interior and exterior joints for a shear distortion of 1%. These limits are similar to those recommended by ACI-ASCE Committee 352 for exterior connections. However, they are lower than those recommended for interior joints. The detrimental effect of eccentricity on joint strength is also estimated. Further analyses are required to fully quantify the effect of joint type and details on the principal strain ratio, and thus on joint strength.