NONLINEAR DYNAMIC ANALYSIS OF REINFORCED CONCRETE STRUCTURES UNDER PROGRESSIVE COLLAPSE: COMPUTATIONAL MODELING, IMPACT LOADING MECHANISMS, AND ROBUSTNESS ENHANCEMENT STRATEGIES

Abstract

Progressive collapse of reinforced concrete structures, triggered by localized damage from events like blast or impact, remains a critical challenge in structural engineering, as evidenced by historical failures. This systematic review critically evaluates the state-of-the-art in nonlinear dynamic analysis for such scenarios, focusing on computational modeling techniques, impact loading mechanisms, and strategies for structural robustness enhancement. We synthesized findings from a broad base of peer-reviewed research, following a rigorous and transparent methodology to ensure comprehensive coverage of the field. The analysis reveals a clear evolution from early simplified experimental studies to sophisticated computational approaches, including continuum-based finite element models, discrete applied element methods, and efficient macromodeling strategies. A key finding is that conventional assumptions of idealized column removal can significantly underestimate the structural demand; instead, realistic impact simulations demonstrate a critical downward pulling force that accelerates failure propagation and alters the transition from flexural to catenary action. Furthermore, we systematically categorized and appraised various enhancement approaches, including externally bonded fiber-reinforced polymers, internal detailing modifications, and passive bracing systems, finding their effectiveness consistently linked to improved rotational ductility and enhanced tensile load paths. The review concludes that no single modeling paradigm is universally superior; the appropriate choice depends on the trade-off between predictive accuracy and computational cost for specific research or design objectives. A major practical implication is the need for design codes to explicitly account for impact-induced dynamic forces and to promote mechanisms like catenary and tensile membrane action. Future work should focus on multi-hazard optimization, ensuring that solutions for progressive collapse do not inadvertently compromise seismic performance or economic feasibility.