Abstract: This study investigates how column material selection reshapes the seismic response topology of space-frame roof systems through a hybrid causal–probabilistic framework. Rather than treating seismic performance as a deterministic outcome, the research conceptualizes space frames as stochastic force networks governed by boundary-defined interventions. Nonlinear spatial finite element modeling is integrated with Monte Carlo simulation, topology-informed robustness metrics, and Bayesian counterfactual inference to quantify how reinforced-concrete and steel columns alter axial force redistribution, nodal demand localization, and progressive failure mechanisms. Results demonstrate that steel-supported systems sustain higher axial force dispersion, greater load-path redundancy, and reduced uncertainty amplification, while reinforced-concrete supports promote force localization and accelerated yielding. Counterfactual analysis confirms statistically significant robustness gains under steel column substitution, with intervention benefits increasing nonlinearly under higher seismic demand. The findings establish column material as a primary causal control parameter governing adaptive seismic robustness in space-frame roofs, advancing resilience assessment beyond conventional response-based design toward topology-aware structural optimization.
Dizaji* et al. (Thu,) studied this question.