Key influence parameters for the joint shear behaviour of reinforced concrete (RC) beam-column connections

An extensive database of reinforced concrete (RC) beam-column connection test specimens exhibiting joint shear failure has been constructed. All test specimens included (with at least a minimum amount of joint transverse reinforcement necessary for proper joint confinement) were subjected to cyclic lateral loading, and had no out-of-plane members (transverse beams or slabs). Major categories within the database include the type of joint shear failure (in conjunction with, and also without, yielding of longitudinal beam reinforcement), as well as connection type (interior, exterior, and knee joint). Influence parameters for joint shear stress and/or strain behaviour at identified key points (displaying the most distinct stiffness changes) have been assessed. Concrete cracking and yielding of joint transverse or longitudinal beam reinforcement triggered the most distinct changes in stiffness, for both overall and local behaviour up to the point of initiation of joint shear failure (maximum experimental storey shear). Examined parameters for joint shear behaviour were grouped by material property, joint panel geometry, reinforcement confinement, column axial load, and reinforcement bond condition. The most important influence parameters on joint shear behaviour were found to be somewhat different by connection type and failure mode sequence. However, concrete compressive strength was the most common governing parameter on joint shear behaviour for all groups in the constructed database. In addition, joint shear cracking stresses and strains (for the point displaying the first distinct stiffness change) were investigated by simple equations. Finally, the design checks recommended by ACI 352R-02 were also examined for the specimens within the constructed database.