Shao-Fei Jiang

This study develops a novel self-sensing cement-soil composite (SSCS) that functions as an integrated sensor for structural health monitoring of ground improvement works. By incorporating industrial by-products (waste carbon black (CB) and steel slag (SS)), the composite achieves a synergistic enhancement of mechanical, electrical, and self-sensing properties. The mix proportions were optimized through an orthogonal experimental design, which investigated the effects of pretreated CB, SS, and cement on the fluidity, unconfined compressive strength (UCS), and electrical resistivity (ER). Range and variance analyses identified the influential factors, and the optimal mix was determined using an efficacy coefficient method. The microstructure and self-sensing were analyzed. The results indicate that SS enhanced fluidity, density, and UCS (by 83.5 %), while CB reduced ER by 2-3 orders of magnitude. Furthermore, a high-accuracy prediction model (with an R²＞0.977) was established for property estimation, and the optimized mixture showed a deviation of less than 9.9% in key parameters. Microstructural analyses revealed that the combined use of CB and SS decreased harmful porosity, with SS promoting secondary hydration reactions and enhancing the bonding between CB and the cementitious matrix. The SSCS enables real-time stress monitoring with a high stress sensitivity of up to 24.0. The findings demonstrate that the synergistic use of CB and SS not only improves the mechanical, electrical, and self-sensing properties of cement-soil, but also promotes the sustainable utilization of industrial by-products, offering a novel and practical solution for intelligent foundation improvement and monitoring.

The quality of underwater bridge piers significantly impacts bridge safety and long-term usability. To address limitations in conventional inspection methods, this paper presents a sonar-based technique for the three-dimensional (3D) reconstruction and visualization of underwater bridge piers. Advanced MS1000 scanning sonar is employed to detect and image bridge piers. Automated image preprocessing, including filtering, denoising, binarization, filling, and morphological operations, introduces an enhanced wavelet denoising method to accurately extract the foundation contour coordinates of bridge piers from sonar images. Using these coordinates, along with undamaged pier dimensions and sonar distances, a model-driven approach for a 3D pier reconstruction algorithm is developed. This algorithm leverages multiple sonar data points to reconstruct damaged piers through multiplication. The Visualization Toolkit (VTK) and surface contour methodology are utilized for 3D visualization, enabling interactive manipulation for enhanced observation and analysis. Experimental results indicate a relative error of 13.56% for the hole volume and 10.65% for the spalling volume, demonstrating accurate replication of bridge pier defect volumes by the reconstructed models. Experimental validation confirms the method’s accuracy and effectiveness in reconstructing underwater bridge piers in three dimensions, providing robust support for safety assessments and contributing significantly to bridge stability and long-term safety assurance.

As a no-disturbance integrated-retrofitting technique, an external rocking frame was widely used on reinforced concrete (RC) structures. Yet, with the increasing demand for seismic strengthening of existing buildings, it has become a concern to evaluate the seismic strengthening schemes based on seismic resilience. Firstly, the dynamic equation of the structural system was derived, and the deformation control mechanism was revealed; thus, the corresponding design method was put forward for the rocking frame reinforcement. Secondly, after soft-first-floor structures were reinforced by rocking frames, the evaluation method of the reinforcement scheme was investigated based on seismic resilience. Finally, the feasibility of the assessment method was verified by a soft-first-floor frame structure, and a comparison was made between the method proposed in this paper and the conventional method. The results find that the soft-first-floor structure reinforced by the rocking frame increased by 10% in the inter-layer displacement and improved by 55.6% and 63.0% in the injury and mortality rates, compared to the buckling-restrained brace scheme. This indicates that the reinforcement scheme of soft layer structures with rocking frames is feasible and effective, and the reinforcement evaluation method proposed in this paper can quantitatively reflect the improvement in seismic performance.