In this study, the scope of CFRP cables in cable-stayed bridges is studied by establishing a numerical model of a 1400-m span of the same. The mechanical properties and characteristics of CFRP stay cables and of a cable-stayed bridge with CFRP cables are here subjected to comprehensive analysis. The anomalies in the damping properties of free vibration, nonlinear parametric vibration and wind fluctuating vibration between steel cables and CFRP cables are determined. The structural stiffness, wind resistance and traffic vibration of the cable-stayed bridge with CFRP cables are also analyzed. It was found that the static performances of a cable-stayed bridge with CFRP cables and steel cables are basically the same. The natural frequencies of CFRP cables do not coincide with the major natural frequencies of the cable-stayed bridge, so the likelihood of CFRP cable-bridge coupling vibration is minuscule. For CFRP cables, the response amplitudes of both parametric vibration and wind fluctuating vibration are smaller than those of steel cables. It can be concluded from the research that the use of CFRP cables does not change the dynamic characteristics of the vehicle-bridge coupling vibration. Therefore, they can be used in long-span cable-stayed bridges with an excellent mechanical performance.

Concrete cracks have always been the focus of research because of the serious damage they cause to structures. With the updating of hardware and algorithms, the detection of concrete structure surface cracks based on computer vision has received extensive attention. This paper proposes an improved algorithm based on the open-source model Deeplabv3+ and names it Deeplabv3+ BDF according to the optimization strategy used. Deeplabv3+ BDF first replaces the original backbone Xception with MobileNetv2 and further replaces all standard convolutions with depthwise separable convolutions (DSC) to achieve a light weight. The feature map of a shallow convolution layer is additionally fused to improve the detail segmentation effect. A new strategy is proposed, which is different from the two-stage training. The model training is carried out in the order of transfer learning, coarse-annotation training and fine-annotation training. The comparative test results show that Deeplabv3+ BDF showed good performance in the validation set and achieved the highest mIoU and detection efficiency, reaching real-time and accurate detection.

Dockless Bike-Sharing (DBS) is an eco-friendly, convenient, and popular form of ride-sharing. Metro-oriented DBS systems have the potential to promote sustainable transportation. However, the availability of DBS near metro stations often suffers from either scarcity or overabundance. To investigate the factors contributing to this imbalance, this paper examines the nonlinear influences and interactions that impact the DBS system near metro stations, with Shenzhen, China serving as a case study. An ensemble learning approach is employed to predict the imbalance state. Then, the machine learning interpretation method (i.e., SHapley Additive exPlanations) is used to quantify the contribution of effects, discover the strength of interactions between factors and uncover their underlying interactive connections. The results indicate the influence of external factors and the relations between pairwise variables (e.g., road density and the day of the week) for each imbalanced state. Provide two quantized sets of factors that can result in the supply-demand imbalance and support future transport planning decisions to enhance the accessibility and sustainability of Metro-oriented DBS systems.

In 2009–2022, to meet the requirement of resilient bridge pier structure (e.g., earthquake resistance, energy dissipation, isolation, resilience) for rapid repair after earthquakes and to improve the suitability of precast segmental bridge piers in medium- and high-intensity areas, a segmental assembled CFST bridge pier with external replaceable energy dissipator was proposed. Based on ABAQUS finite element analysis software, the finite element model of the CFST pier is established to analyze the force of the external replaceable energy dissipator, and the feasibility of the external energy dissipator is verified. Thereafter, two groups of segmentally assembled CFST pier model structures were tested for seismic behavior under reciprocating loading. Non-linear mechanical behaviors, such as restoring force-displacement hysteresis, loss of prestressing, and opening of the indirect joint of a segmented precast assembled pier, are analyzed. The results show that compared with a CFST pier with an energy dissipator, the lateral bearing capacity of the CFST pier with an external energy dissipator is increased by 32.8%, the energy dissipation capacity is also significantly improved, the opening size of joints between segments is reduced, and the overall damage of the CFST pier is concentrated on the energy dissipator, which is convenient for rapid disassembly and replacement. At the same time, the seismic performance of the CFST pier after replacing the energy dissipator is analyzed. The results show that the replacement of the external energy dissipator will not affect the seismic performance of a segmental assembled pier.