Urban infrastructure (UI), subject to ever-increasing stresses from artificial activities of human beings and natural disasters due to climate change, assumes a key role in modern cities for maintaining their functional operations. Therefore, understanding UI resilience turns essential. Based on the Pressure-State-Response (PSR) model, this paper built a comprehensive evaluation index system for urban infrastructure resilience evaluation. Four municipalities, including Beijing, Tianjin, Shanghai, and Chongqing in China, were selected for the case study, given their specific significance in terms of geographical location and urban infrastructure scale. Temporal differences of UI resilience in those four cities during 2002–2018 were explored. The results showed that: (1) The various stages of PSR relative importance for the urban infrastructure resilience development in the four cities were different. The infrastructure status, primarily resource environmental benefit, had the most significant effect on urban infrastructure resilience, accounting for 38.73%. (2) While Shanghai ranked first, the levels of urban infrastructure resilience in four cities were generally poor in 2002–2018 with continuously low resilience. (3) Significant differences were found in the resilience levels associated with the three stages of pressure, state and response failing to form a positive development cycle, with the poorest pressure resilience. This paper puts forward some recommendations for providing scientific support for urban resilient infrastructure development in four municipalities in China.

The recycling of construction waste is key to reducing waste generation and CO₂ emissions. This study aimed to develop a quantitative model for analyzing the carbon reduction potential of recycling construction, demolition, and renovation waste (CDRW) in Jiangsu province. The waste generation rate calculation method and nonlinear autoregressive artificial neural network model were used to estimate and predict CDRW generation. The life cycle assessment was performed to calculate the carbon reduction potential of recycling CDRW. In quantifying the carbon reduction potential, not only construction and demolition waste, but also renovation waste was considered for the first time. The results showed that the total carbon reduction potential of recycling CDRW increased from 3.94 Mt CO₂e in 2000 to 58.65 Mt CO₂e in 2020. Steel and concrete were the main contributors. By scenario analysis, the carbon reduction potential of fully recycling CDRW in 2020 increased by 37.79 Mt CO₂e, a growth rate of 64%. The study further predicts future CDRW generation and the corresponding carbon reduction potential. Our conclusions indicate that 245.45 Mt of CDRW will be generated in 2030, and carbon reduction potential may reach 82.36 Mt CO₂e. These results will help the government manage construction waste better and reach early achievement of the carbon peak target.

Sand content plays a critical role in regulating the structural compactness and strength development of alkali-activated slag cementitious materials. In this study, three types of specimens—pure slag paste, standard sand mortar, and fine sand mortar—were prepared to investigate the effects of sand incorporation on pore structure and fractal characteristics. Mechanical properties, pore structure, and micro-morphology were systematically evaluated at different curing ages. Mercury intrusion porosimetry (MIP) was employed to measure porosity, pore size distribution, and the threshold pore diameter, while fractal dimensions were calculated to quantify pore complexity and compactness. The results showed that the pure slag paste achieved the highest compressive strength at all ages but posed environmental concerns due to high resource consumption. In contrast, sand-incorporated mortars exhibited stable strength development and continuous pore structure refinement. Notably, the use of fine sand in Group C reduced slag content by approximately 5.6% compared to Group A, contributing to lower CO₂ emissions and enhanced sustainability. Fractal analysis revealed a strong correlation between fractal dimension, pore compactness, and compressive strength. A higher fractal dimension indicated a more complex and interconnected pore network, promoting matrix densification. At 90 days, Group C achieved the highest fractal dimension and lowest porosity, attributed to the micro-filling effect of fine sand, which facilitated the formation of a denser and more continuous gel network. These findings provide a theoretical foundation for the multiscale characterization of alkali-activated cementitious systems and support the design of more sustainable mix formulations.

This paper treats the vibration characteristics of three different types of asymmetric buildings and investigates the feasibility of applying an innovative vibration‐based multicriteria approach‐based damage index (MCA‐DI) technique to detect the damage. This technique combines a modified form of the traditional modal strain energy method (MSEM) developed by decomposing the mode shapes into lateral and vertical components together with a modified form of the modal flexibility method to define a new damage indicator. Lastly, the dynamic behavior of three asymmetric building instances, including a 10‐storey L‐shaped structure, a 10‐storey setback structure, and a 6‐storey reinforced concrete structure with an unsymmetrical distribution of columns, was studied under five different damage scenarios. The results showed that despite different vibration characteristics of these three asymmetric buildings, the proposed method was able to accurately and effectively locate all damages and eliminate the confusion when more than one index is simultaneously used by using only the first a few modes.