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Abstract With the development of recycled aggregate concrete (RAC), the recovery rate of construction waste is improved, and the pollution problem is alleviated. In particular, RAC beams strengthened with prestressed carbon fiber reinforced plastics (CFRP) can exhibit improved mechanical properties, expanding RAC application. Four groups of reinforced RAC beam specimens contained 0%, 40%, 70%, and 100% recycled coarse aggregate, respectively. Each group of beams was first pre-cracked and then strengthened by prestressed CFRP with one layer and two layers respectively. Finally, the bearing capacity tests were performed for these beams. The test results show that as the recycled coarse aggregate content increases, the cracking moment and ultimate load capacity of the beam decrease, while its crack width increases. As the CFRP layer increases, the deformation and crack width of the beam decreases, while the number of cracks increases. The prestressed CFRP also exhibited tensile and peeling failure. A beam deflection calculation model was established by introducing a coefficient k representing the interaction between recycled aggregate and CFRP. The influence coefficient of concrete elongation on the crack width and average crack spacing of the beam was modified, and the crack width analysis model of the beam was established. The calculated results are in good agreement with the experimental observations. It can provide reference for the application and design of recycled concrete beams strengthened with prestressed CFRP.

Abstract Recycling scrap tires provides an alternative source of fine aggregates for the production of rubberized concrete and this will lead to significant increase in concrete frost resistance, environmental protection, and conservation of natural sand and gravel resources. In this paper, a total of 25 groups of rubberized concrete were produced by adding scrap tire rubber particles of different sizes, contents, and pretreatment methods to replace the fine aggregate, and their compressive strength during freeze–thaw cycles was studied from both the macro- and meso-perspectives. The results indicated that the decrease in concrete strength and weight was notably restricted by the presence of rubber particles during freeze–thaw cycles. The rubber fine aggregate with smaller particle sizes enhanced the concrete frost resistance more significantly, and the F 100 of concrete with rubber particles of 1.0–2.0 mm increased from 76.6 to 86.5% by increasing the rubber content from 0.0 to 5.6%. The effects of rubber fine aggregate on concrete compressive strength during freeze–thaw cycles were quantified. On this basis, a forecast model for rubberized concrete compressive strength in freeze–thaw cycles was proposed, and the effects of the particle size, content, and pretreatment of the rubber particles were considered. The calculated results agreed well with the test results both in this study and the relevant peer studies, indicating that the model can provide a good reference for the design and engineering application of rubberized concrete in frigid environments.

A planar construction drawing is usually used to guide the construction of reinforced concrete structures in the construction industry. Due to a lack of effective technical methods, the accuracy of rebar engineering lofting is insufficient. The rejection rate of rebar is high, which results in high processing costs. Under the background of intelligent construction and BIM technology, the prefabricated factory adopts an automatic production mode to concentrate on steel bar processing, which improves production quality and processing efficiency and reduces production costs. Based on Revit secondary development, using the C# programming language, combined with the Revit API development interface, an automatic 3D modeling plugin for a reinforced concrete variable cross-section column is developed. The BIM model of steel bars is quickly generated, and the engineering quantity of steel bars is automatically calculated, which saves time for the designer to build the BIM model. It is conducive to the automatic assembly and intelligent construction of reinforced concrete engineering, which promotes the information and intelligent development of reinforced concrete structure construction.

Building Information Modeling (BIM) is a digital tool that can be used to create three-dimensional models of components. BIM technology, with its parameterized modeling scheme, can effectively address design changes. The use of BIM technology in prefabricated shear wall structures can significantly enhance component design accuracy and production efficiency. The Tekla software offers significant advantages in BIM deepening design. By utilizing the C# language, secondary development of the Tekla software, and the development of an intelligent modeling program for the edge components of prefabricated shear wall structures, the deepening design efficiency of such structures can be improved. The creation of BIM models is a crucial step in program development. Different types of reinforcements require various modeling methods, which, when combined with the design specifications of concrete structures, can be compiled to create the fine reinforcement model. This allows for the automatic creation of three-dimensional reinforcement models: “linear-shaped,” “T-shaped,” and “L-shaped” joints of the edge member. The BIM visualization characteristics can then display the three-dimensional model of the steel bar of the edge member in the cast-in-place area, deriving the engineering quantity of the steel bar for the production and construction of the prefabricated members. The modeling program’s development concept can serve as a reference for similar engineering applications, promoting the intelligent development of prefabricated building design and enhancing the efficiency of design and construction.