Large-span structures may experience progressive collapse involving complex member collisions, for which efficient and accurate simulation remains a challenging problem in engineering practice. Conventional finite element methods are computationally inefficient in such scenarios due to repeated reconstruction of contact constraints and global stiffness matrices, while existing member discrete element method (MDEM) approaches lack a unified contact algorithm capable of handling both “point–line” and “line–line” contact modes. To address these limitations, this study extends the MDEM framework for structural collision analyses by establishing unified “point–line” and “line–line” contact models. A “virtual contact point pair” concept was introduced to define critical contact constraints, and corresponding contact force formulations were derived. A Fortran-based computational program was developed. Numerical validation through typical examples showed that the maximum relative error was 4.2% for the elastic ring problem and 3.1% for the double cantilever beam, while the rebound angle deviation in the flexible ring impact case was less than 2°. The proposed method avoids global stiffness matrix reconstruction and achieves a 95–98% accuracy compared to reference solutions under recommended parameters, providing an efficient approach for simulating member collisions in large-span structural collapse and supporting engineering analyses and design.
Xu et al. (2026) studied this question.