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Volume 3, Issue 3, 2025

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The risk of catastrophic flooding from sequential dam breaches in cascade reservoir systems has become increasingly critical under the influence of complex climate change and extreme geological events. In this study, a two-dimensional hydrodynamic dam-break model was developed to analyse flood propagation and inundation dynamics for the $RE1$, $RE2$, and $RE3$ cascade reservoirs in the lower Southwest China River Basin, considering various instantaneous full and partial collapse scenarios. Four distinct scenarios were simulated to evaluate breach characteristics and inundation impacts. Notably, Scenario 3-involving the simultaneous instantaneous full collapse of all three reservoirs-produced peak flow rates of 341,200 m$^3$/s, 1,157,900 m$^3$/s, and 340,100 m$^3$/s at $RE1$, $RE2$, and $RE3$, respectively. Under this worst-case scenario, maximum inundation depths at representative sites A, B, C, and D reached 69.51 m, 79.87 m, 77.16 m, and 48.38 m, with high-severity flooding areas extending over 0.95 km$^2$, 1.10 km$^2$, 1.21 km$^2$, and 1.73 km$^2$, respectively. In comparison, Scenarios 1 and 2 generated lower peak flow rates, smaller inundation areas, and less severe flooding, while Scenario 4-representing overtopping without structural breach-resulted in a substantial reduction of high-risk zones. The findings highlight the pronounced escalation of flood risk under simultaneous multi-reservoir collapse conditions and underscore the necessity for enhanced coordinated flood management and emergency response strategies in cascade reservoir systems. This study offers valuable insights into dam failure risk assessment, contributing to improved flood mitigation policies and emergency preparedness in regions vulnerable to extreme hydrological events.

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To facilitate a rigorous evaluation of damage progression in in-service steel frame structures subjected to seismic loading, a seismic damage model that integrates the effects of atmospheric corrosion has been developed. Corrosion-induced deterioration significantly influences the structural integrity of bolted steel frames, yet its impact on seismic performance remains inadequately quantified. In this study, a performance-based seismic damage assessment framework has been established, wherein corrosion-related degradation is incorporated into the structural damage evolution process. Drawing on an extensive review of domestic and international research, a refined damage index classification system has been formulated to characterize varying levels of structural impairment. To validate the proposed model, a seismic collapse simulation was conducted on a 1:4 scaled-down steel frame specimen, enabling a comprehensive analysis of damage accumulation over different service durations. The results confirm that the developed model accurately captures the progressive deterioration and collapse behavior of corroded steel frames under seismic excitation. This study provides a quantitative basis for assessing the post-earthquake residual load-bearing capacity of in-service bolted steel frame structures, offering critical insights for structural resilience evaluation and maintenance planning.

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This study presents a comprehensive comparison of modern cementitious composites, including UHPC, ECC, and GFRC, with traditional Ordinary Portland Cement (OPC) and ancient Opus Caementicium (Roman). Emphasis is placed on mechanical, physical, and rheological properties, as well as environmental and durability aspects. Advanced composites demonstrate superior short-termmechanical performance and improved impermeability, while Roman binders exhibit unparalleled long-term resilience in marine environments. Furthermore, the integration of pozzolanic materials and industrial by-products in contemporary mixes highlights ongoing efforts toward sustainable construction. Recent developments in China, including metakaolin–slag blends and nano-silica additives, as well as bio-inspired self-healing approaches, illustrate promising pathways for reducing carbon footprint and enhancing durability.

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