In the freight railway bridge, the increase of the train running speed and train axle loads can enlarge dynamic response (DR) of the railway bridges, which leads to excessive vibration of bridges and endangers the structural safety. In this paper, a three‐dimensional coupled finite element (FE) model of a heavy‐haul freight train‐track‐bridge (HHFTTB) is established using multibody dynamics theory and FE method, and the DR for the coupled system of HHFTTB are solved by ABAQUS/Explicit dynamic analysis method. The field‐measured data for a 32 m simply supported prestressed concrete beam of a heavy‐haul railway in China are analyzed, and the validity of the FE model is verified. Finally, the effects of train formation number, train running speed, and train axle loads on DR of the heavy‐haul railway bridge structures are studied. The results show that increasing the train formation number only has an influence on DR duration of the bridge structure, rather than the peak value of DR, when the train formation number exceeds a certain number; besides, the train axle loads and train running speed have significant influence on DR of the bridge structure. The results of this study can be used as reference for the design of heavy‐haul railway bridges and the reinforcement transformation of existing railway bridges.

In this work, to further investigate the vegetation concrete technology for slope protection, a total of 10 groups mix proportion specimens of porous concrete were designed and constructed. As a result, the impacts of different parameters include the fly ash and silica fume contents on the mechanical properties and porosity as well as the pH value of porous concrete were discussed. Meanwhile, ecomodified soil with resistance to the erosion of rainwater was sprayed on the surface of porous concrete for the survival of native grass growth. In addition, the growth characteristics of the Festuca arundinacea schreb (Chinese grass) within eco-modified soil on the surface of porous concrete were observed and monitored for 8 weeks including the average height, root system development and relative coverage of grass. The results show that the compressive strength and porosity of porous concrete measured after 28 days were at least 13Mpa and 21% respectively, indicating the porous concrete is suitable for the slope protection in practical engineering. Furthermore, the integration of eco-modified soil and porous concrete was successful, and all grass survived in the eco-modified soil and porous concrete environment for the duration of the observation period, and the coverage rate of vegetation reached 96% or above. It was also found that the roots system has permeated the pores of porous concrete and reached the bottom of porous concrete after 8 weeks.

Rebar corrosion is the primary cause of the durability degradation of reinforced concrete (RC) structures, where non-uniform corrosion is the typical pattern in engineering. This study experimentally and numerically investigated the tensile degradation properties of non-uniform corroded rebars. Corrosion morphology was accurately determined by three-dimensional (3D) laser scanning techniques, studying the characteristics of longitudinal non-uniform corrosion. The results showed that the non-uniformity of corrosion increased with an increase in corrosion levels. From tensile tests, the differences in nominal stress–strain curves among rebars with similar average corrosion levels indicated that corrosion non-uniformity has appreciable effects on the tensile behavior of rebars. The residual load-bearing capacity of corroded rebars was dominated by the reduced critical cross-section, while residual ductility was associated with the cross-section loss throughout the entire length of rebars. The degradation relations of nominal yield and ultimate strength, ultimate strain, and elongation after fracture were better correlated to the maximum cross-section loss than to the average volume loss. Additionally, numerical calculation based on the cross-sectional areas of corroded rebars was conducted to evaluate the tensile behavior of non-uniform corroded rebars. Equivalent distribution models simulating the longitudinal non-uniform corrosion were proposed, on the basis of probability characteristics of cross-sectional areas, for practical application of the numerical method.

As one of the key ways to realize the industrialization and green development of construction, prefabricated construction is conducive to saving resources and energy and improving labor productivity and quality. Aiming to solve the problem of the lack of standardization in the design of prefabricated residential buildings, which leads to the components not being universally used and the industrial characteristics not being fully embodied, while excessive standardization leads to a lack of personalization and flexibility, the modular design theory is applied to the standardized design of prefabricated residential buildings in this study. The application route of modular design theory in the standardized design is constructed, that is, “system decomposition—module design—module combination”. Taking residential buildings within a height of 54 m as an example, each basic functional module is standardized and combined into standard plans. At the same time, the functional space module design based on modular coordination and the module combination design based on the trinity of “modulus, pattern, and mode” are discussed. This research is of great significance for giving full play to the comprehensive benefits of prefabricated concrete structures in quality improvement, cost reduction, and rapid assembly.

The CO₂ concentration of urban residential green space in Changsha was experimentally investigated. Based on the experimental results, the variation characteristics and influencing factors of CO₂ concentration in residential areas were analyzed considering both the measuring time and ecological plant structure. Then, through the concept of urban ecological bearing capacity, the carbon sequestration index of the urban residential areas was proposed in this paper. Finally, the regulating effects of varieties of vegetation on CO₂ concentration among four urban residential areas were deeply analyzed and discussed. Results showed that green space with an ecological plant structure of trees-shrubs-grass exhibited greater improvement in the environmental carbon balance than those of shrubs or grass, and the atmospheric carbon sequestration capacity was significantly affected by the total quantity of the green space.

During the installation process of prefabricated components, deviations in dimensions and installation positions can occur due to construction quality issues, and the accumulation of these deviations can impact the reliability of component installation. However, the current approach to addressing accumulated deviations in the component installation process primarily relies on the trial-and-error method, lacking a solid theoretical foundation. This paper introduces the dimensional chain theory derived from mechanical engineering and presents a method to evaluate the installation reliability of prefabricated components in concrete structures. First, based on extensive measurements of installation deviations, it was found that the installation deviations of components followed a log-normal distribution. By analyzing the relationship between installation deviations and the acceptance rate, it was determined that for a 90% acceptance rate, the installation position deviation should be 8.6 mm for prefabricated wall panel components and 7.3 mm for prefabricated column components. Subsequently, the concept of dimensional chain theory from mechanical engineering was introduced to establish a limit state equation for quantifying the installation reliability of prefabricated components in concrete structures. By applying this theory, appropriate component fabrication dimensions could be determined to achieve a 95% level of installation reliability. Finally, by using the Monte Carlo method to solve the installation limit state equation for an actual engineering project, recommended fabrication dimensions for the components were obtained. The results indicate that within the horizontal axis, the length deviation of prefabricated beams, and the width fabrication dimension of columns needed to be reduced by 2.3 mm to 2.9 mm. Within the vertical axis, the length dimension of columns and the height dimension of beams had to be reduced by 0.9 mm to 2.2 mm to achieve a 95% level of installation reliability.