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For low-carbon sustainability, recycled rubber particles (RPs) and recycled aggregate (RA) could be used to make rubber-modified recycled aggregate concrete (RRAC). The characteristics (compressive strength and peak strain) of RRAC with various amounts of RA and RPs after heating at various temperatures were studied in this work. The results show that high temperatures significantly decreased the uniaxial compressive strength (UCS), whereas the addition of RA (e.g., 50%) and RPs (e.g., 5%) can mitigate the negative effect caused by high temperatures. The peak strain can also be improved by increasing the replacement ratios of RA and RP. Support vector regression (SVR) models were trained using a total of 120 groups of UCS and peak strain experimental datasets, and an SVR-based multi-objective optimization model was proposed. The excellent correlation coefficients (0.9772 for UCS and 0.9412 for peak strain) found to illustrate the remarkable accuracy of the SVR models. The Pareto fronts of a tri-objective mixture optimization design (UCS, strain, and cost) were successfully generated as the decision reference at varying temperature conditions. A sensitivity analysis was performed to rank the importance of the input variables where temperature was found as the most important one. In addition, the replacement ratio of RA is more important compared with that of the RP for both the UCS and strain datasets. Among the mechanical properties of concrete, compressive strength and peak strain are two key properties. This study provides guidance for the study of RRAC constitutive models under high temperatures.

In this paper, a total of six different ribbed and two nonribbed L‐shaped concrete‐filled steel tubular (CFST) short columns are designed; finite element modeling and calculations are carried out and verified with measured results. The optimal ribbing method among the ribbing methods applied is proposed. The mechanisms of the longitudinal stress of the concrete, longitudinal stress of the outer steel tube, and lateral compressive stress of the concrete for the L‐shaped CFST short column without ribs and with the optimal ribbing method are compared and analyzed. The results show that the optimal ribbing method involves setting half‐width longitudinal stiffening ribs in the middle of the two wide sides of the L‐shaped steel tube. The stiffening ribs can delay the occurrence of local buckling failure of the steel tube, thus strengthening the restraining effect of the steel tube on the concrete and improving the uniformity of the longitudinal stress of the core concrete. In addition, based on an analysis of a large number of parameters, four methods for calculating the bearing capacity of nonribbed L‐shaped CFST short columns are compared. A design formula for the bearing capacity of ribbed L‐shaped CFST columns is proposed by considering the improvement in the concrete performance. The calculation results agree well with the finite element and experimental results, and the error is <5%. [ABSTRACT FROM AUTHOR]

Bridges are critical infrastructure, and effective operation and maintenance (O&M) is essential for ensuring the good condition of bridges. Owing to the increasing complexity of modern bridges and the availability of information technologies (e.g. sensors, laser scanners, and ultrasonic radar) for the collection of massive data, bridge O&M and decision-making gradually shift toward a data-driven manner. However, both the bridge industry and the academia still do not have a common understanding of the latest progress, challenges, and trends of data-driven bridge O&M decision-making. Thus, through a critical review of 485 articles, this paper investigates current data-driven bridge O&M decision-making in detail, including mainstream data types, issues related to data management, and typical application areas using these data. Challenges to implement data-driven bridge O&M decision-making are identified, such as lack of standard data needs, lack of data integration, and lack of standard procedures. Future research opportunities to address the challenges are proposed. This paper can help bridge O&M teams by identifying suitable data and applications to make informed decisions that align well with their needs meanwhile serve as a basis for future research efforts in this area. [ABSTRACT FROM AUTHOR]

This paper presents a new surface treating technology using silane coupling agent KH-550 to strengthen coarse recycled ceramic vase aggregates (CRCVA) with the purpose of enhancing the bond strength between CRCVA and mortar, and consequently improving the properties of recycled concrete made with CRCVA. In the proposed technology, the optimal KH-550 solution concentration and recycled aggregates' soaking time are 4% and 100 min, respectively, resulted from orthogonal test. Mechanical and durability property tests, on concrete mix made with coarse natural aggregates substituted by surface-treated CRCVA, were conducted to determine the optimal incorporating ratio of CRCVA and verify the feasibility of the proposed technology. Test results are highly promising up to an incorporating ratio of coarse natural aggregates with CRCVA of 60%, and show that the proposed technology could enable the recycled concrete mix, made with treated CRCVA, maintain better properties than that of natural concrete containing only coarse natural aggregates. Supplement verification through stereoscopic microscope test further confirms that the proposed technology could make the interfacial transition zone much more compact, resulting an efficient bond strength between ceramic aggregates and mortar. [ABSTRACT FROM AUTHOR]