Optimal seismic design method to induce the beam-hinging mechanism in reinforced concrete frames

The strong-column weak-beam design criterion is widely used in seismic design procedures to prevent the abrupt collapse of reinforced-concrete (RC) frames and to secure their ductility capacity. However, many studies have demonstrated that the column-hinge collapse mechanism in RC frames can occur even if the strong-column weak-beam design criterion is satisfied. This study presents the automated optimal seismic method to induce the beam-hinging mechanism in RC frames. The proposed optimal seismic method uses constraints on 1) the strengths of the beams and columns, 2) the column-to-beam flexural strength ratio, and 3) the prevention of plastic hinges of columns at the joints. Two objective functions are used to minimize the structural cost and maximize the energy dissipation capacity. The non-dominated genetic algorithm II (NSGA-II) is employed as an optimization tool. A linear static analysis method is employed to evaluate the constraints on the strength of members, and a nonlinear static analysis method is employed to evaluate the energy dissipation capacity and the constraint on the plastic hinge. The multi-core based parallel analysis is adopted to accelerate the optimization process. Finally, a four-story RC moment frame is employed to verify the proposed method.