An improved YOLOv8 model, YOLOv8‐NETC, is proposed in this study for fine‐grained crack recognition through instance segmentation. YOLOv8‐NETC is designed and enhanced with four self‐developed modules. First, ablation studies were conducted to assess the effectiveness of each module. The model’s accuracy and speed were evaluated based on parameters such as mean average precision (mAP50) and model weight (MW). The experimental results show significant improvements in accuracy, storage efficiency, and processing speed. Compared to the original network, YOLOv8‐NETC achieved a 6.5% increase in mAP50, a 6.1% average reduction in MW and parameters, and an 8.5% improvement in FPS. Subsequently, YOLOv8‐NETC was compared with other state‐of‐the‐art models across three datasets, including the crack type dataset, crack trueness dataset, and the public Crack500 dataset. The experimental results demonstrate that the proposed model achieved the best recognition performance on all datasets. Furthermore, YOLOv8‐NETC showed superior robustness against interference and computational efficiency compared to other benchmark models.

A precast concrete sandwich panel (PCSP) offers a good potential in the application of façade wall due to the improved energy efficiency. In this study, the structural performance of PCSP with pin-type glass fiber reinforced polymer (GFRP) connectors was investigated, and an optimization characterized by ribbed structural wythe was proposed and studied. Firstly, the pull-out and shear capacity of the pin-type connector were evaluated through direct tensile test and direct shear test, respectively. Thereafter, seven PCSP specimens were fabricated and tested under four points flexural load. The investigating parameters included the structural wythe thickness, loading direction, insulation bond, and section type of the structural wythe. The load-deflection relationship, crack pattern, failure mode, load-strain relationship, and degree of composite action of the PCSP were studied and compared. It was concluded that: (1) the tested PCSPs presented ductile failures; (2) the structural wythe thickness, loading direction and insulation bond would influence the cracking, yielding, and peak loads of the tested PCSP; (3) the PCSP with pin-type GFRP connectors could be designed as non-composite type owing to the low composite action; and (4) the proposed ribbed structural wythe could achieve a lightweight PCSP while considerable flexural stiffness and capacity could be retained.