Linking structural safety and embodied carbon during service for low-carbon design of concrete structures under climate change

Conventional Life Cycle Assessment (LCA) of concrete structures typically presumes safe service throughout the lifespan, overlooking the probabilistic carbon liabilities associated with potential structural failure. This study addresses this critical gap by quantifying the coupled evolution of structural safety and embodied carbon under climate change, identifying a significant underestimation in current carbon accounting. By integrating empirical models for reliability, degradation, and maintenance across Shared Socioeconomic Pathways (SSPs), we quantify how the structural degradation accelerated by climate change amplifies the risk of unintended emissions. Results reveal that potential carbon consequences driven by increased failure risks due to concrete carbonation can negate its widely recognized carbon uptake benefits. Under climate change, these failure-related emissions may escalate to levels comparable to or even exceeding safety-conditioned embodied carbon (i.e., conventional LCA outcomes), particularly for a structure group in which low-reliability individuals disproportionately amplify failure-related emissions. While planned maintenance can mitigate failure-related emissions with lower additional emissions, inadequate consideration of the unforeseen risks imposed by climate change may render these controls ineffective. Additionally, minimizing construction quality variability is identified as critical for regulating failure-related emissions at the group level. Furthermore, to address the challenges in accurately quantifying failure-related emissions, we advocate adopting low-carbon conditional probability verification for low-carbon structural design. This provides a robust foundation for reliable, proactive carbon regulation grounded in conventional LCA outcomes, ensuring that the hidden carbon liabilities associated with failure risks are accounted for.