A General Framework for Determining a Target Failure Mechanism in Frame Structures

Guiding structural failure toward a prescribed failure mechanism can significantly mitigate the risk of collapse under extreme seismic action. However, quantitative criteria for identifying the target failure mechanism remain underdeveloped. To fill the gap, this work proposes a general framework for determining a target failure mechanism in frame structures. First, a generalized lateral failure mechanism is introduced and rigorously defined. Second, a topology-based search algorithm is developed to identify the minimal cut sets of failure mechanisms. On this basis, a two-stage evaluation procedure is proposed to identify the governing failure mechanism via the upper-bound theorem and subsequently determine the target failure mechanism through a max–min capacity criterion. Finally, 36 case studies covering three frame topologies are investigated. Results indicate that: (1) the selection of the target mechanism should be case-specific rather than determined solely by engineering intuition; (2) the target mechanism is controlled by structural topology, design constraints, and inter-story height distribution; and (3) across all topologies, increasing γ(0) consistently shifts the selected target failure mechanisms toward configurations with a lower proportion of column hinges. Numerical pushover validation further confirms the mechanical consistency of the proposed framework, with the ultimate capacities obtained from the proposed method agreeing well with nonlinear simulation results. The proposed framework provides a theoretical basis and practical tools for failure-mechanism-based seismic design, with implications for improving structural safety and reliability.