Enhancing the Structural Performance of RC Beam-Column Joints Using a Novel Optimized Stochastic Lattice Structure

Abstract

Beam-column (BC) joints play an important role in the seismic performance of moment-resisting RC frame structures. Several techniques have been suggested to improve the seismic efficiency of BC joints, but these techniques have been criticized for being labor-intensive and/or vulnerable to premature debonding. To overcome these deficiencies, a novel stochastic lattice structure is proposed in this work to improve the shear-deficient RC BC joints. The optimization procedure was carried out for different shapes of stochastic lattice structures that give the maximum shear capacity, and the shear capacity is compared with the designed exterior standard beam-column joint. The expression for shear capacity of the stochastic lattice structure was formulated by considering a unit cell of 10 mm length. The maximum shear capacities of the triangle, hexagon, and pentagon shapes were obtained by varying the cell angle and length. The results of different cell shapes were compared with the allowable shear stress of designed beam-column joints. In addition to the optimization procedure, three-dimensional (3D) finite-element (FE) models were developed to study the behavior of the joints using the optimized stochastic lattice in the joint core. Compared with the control specimen, the beam-column joints with the proposed lattice give much better performance in terms of cumulative energy dissipation, lateral stiffness, joint shear deformation, and angle of beam rotation.