Open-source MATLAB framework for MDOF seismic response using real earthquake records

This study develops an open-source, MATLAB-based simulation framework that evaluates the dynamic behavior of multi-degree-of-freedom (MDOF) systems, both elastic and bilinear inelastic, when subjected to real earthquake ground motions. Ground motion datasets from the PEER NGA-West2 database were utilized to analyze a range of input accelerograms applied to representative structural models, including low- to mid-rise frames with varying story stiffness, damping ratios, and inelastic hinge properties. A custom MATLAB function was implemented to plot multi-story hysteresis loops for selected stories of the MDOF system. This script forms part of the modular workflow, and it enables direct visualization of story shear versus inter-story drift across selected floors. In addition to supporting research reproducibility, it also serves as a pedagogical aid for students to explore nonlinear response characteristics in MDOF systems. This open-access solver offers scalability, transparency, and adaptability for researchers, engineers, and educators. Beyond its technical contributions, it supports global resilience initiatives by advancing disaster preparedness, resilient infrastructure, and equitable seismic education in line with multiple UN Sustainable Development Goals. Unlike prior MATLAB solvers limited to single-degree-of-freedom models or lacking systematic benchmarking, this framework introduces a validated MDOF solver with modular architecture, benchmarked against OpenSees and extended to case studies using 10 real earthquakes.