Evaluation of Hexagonal Surface Model for Seismic Response Analysis of Multi-Story Structure

The hexagonal plastic collapse surface model has been explored as an effective approach for seismic response analysis in multi-degree-of-freedom (MDOF) structures. This study establishes the theoretical background of hexagonal analysis for multistory structures, emphasizing the consistency between experimental and analytical results. A simplified nonlinear dynamic analysis (SNDA) is introduced, integrating limit analysis with static proportional loading and a hexagonal plastic collapse surface model to define the internal safety zone within the mode restoring force space. The approach considers multiple vibration modes, which significantly impact elastic–plastic behavior in seismic conditions. To validate its effectiveness, a comparative evaluation is conducted between experimental data and SAP2000 dynamic time history analysis, showing strong alignment in deformation response trends. The results confirm that the hexagonal model accurately predicts failure mechanisms while improving computational efficiency, providing a practical framework for collapse prediction in structural engineering applications.