The perforated rib shear [Perfobond Leiste in German (PBL)] connector is a type of shear connector used in some steel–concrete composite bridges as a main load-transfer element between the concrete roadway and the supporting steel deck. The shear capacity of PBL connectors is affected by several connection parameters, such as the diameter of the transverse steel reinforcement, the size of the perforated rib hole, and the thickness of the rib plate, and the stress state in the surrounding concrete. In the present study, 33 test specimens were designed, and push-out tests were performed to investigate how these parameters affect the shear capacity of PBL connectors. The test results show that the shear capacity of these connectors increased with an increase in the diameter of the transverse reinforcing bar, an increase in the size of the rib holes, and an increase in thickness of the perforated rib plate. As for the effect of concrete stress state, it was found that the shear capacity of the connectors increased when a transverse compressive stress was present, but it decreased when a transverse tensile stress was present. Using results from these tests, a design equation that takes all of these factors into consideration in determining the shear capacity of PBL connectors is proposed. The proposed equation produces reasonably accurate results when compared with experimentally determined shear capacity for these connectors.

In this paper, a two-dimensional (2D) model for wave-current girder interactions is established to investigate the effect of wave-current forces on box girder bridges. Reynolds averaged Navier-Stokes (RANS) equations combined with the k-ε turbulence model are applied for wave-current simulations, and the volume of fluid (VOF) method is used to trace the free water surface. Compared with previous studies, this paper (1) investigates the influence of the current velocity on the wave force on a coastal bridge box girder under extreme conditions, (2) analyzes the wave forces on the vulnerable positions of a box girder bridge, and (3) proposes simple and accurate equations for predicting the wave-current forces on a box girder bridge. The numerical model presented in this paper is first validated by comparing data obtained from the laboratory experiments. Next, parametric studies are conducted to examine the influence of the current velocity on wave-current forces under different effect factors, including extreme wave characteristics, relative water depths, and submerged depths. The influence of the geometrical shape of the box girder on the wave forces is considered. Finally, based on the numerical results, empirical equations predicting the wave-current forces on a box girder bridge under various effect factors are proposed as a method of protecting coastal bridges from damage under extreme wave loadings.

To study the bond performance between shotcrete and rock in a hot and humid tunnel, experiments on wet-sprayed shotcrete specimens under different hot and humid curing conditions (35°C, 50°C, 70°C, and standard curing conditions: 20°C with relative humidity 95%) were performed to examine the influence of thermal damage. The results show that the bond strength at 35°C is higher compared with that at standard curing conditions, but decreases when the temperature rises (especially at 70°C), indicating the adverse effects of thermal damage on bond strength. Based on these results, we used the worst hot and humid condition (70°C) as a case study to explore measures to improve bond strength under hot and humid conditions by adding mineral admixture or fiber material to the shotcrete mix. The experimental results suggest that adding fly ash or slag powder can enhance the bond strength, with the best effect achieved by adding fly ash.

Technology of shield tunneling has been widely used in modern city subway system building, however, due to the limit of urban construction land resources, it is inevitable for the new building structures conflicted with existing one. Thus, it is essential to taking correct measures to guarantee the safety of existing structure. In this case, a typical case of metro shield tunnel crossing through city overpass bridge piles underpinning construction project is studied by the numerical method and site field monitoring. According to the existing overpass bridge structure, geological conditions and site operation environment, a suitable construction method of piles foundation underpinning plan for this project is adopted. In order to ensure the structure safety of the existed overpass bridge during the pile foundation underpinning construction, a numerical simulation model is established which takes the whole foundation underpinning structure and construction steps into consideration. The numerical simulation result shows that the stress and the settlement of the piles foundation underpinning structure is reasonable. After the comparing of the site monitoring data with the numerical model simulation results, it is found that the site settlement and stress results are highly consistent with the calculated results, and it proves the feasibility of the piles foundation underpinning construction scheme. Eventually, the site gauging settlement data of the overpass pier and the pile cap indicate that the original overpass structure is barely affected by the shield tunnel construction, the construction method can provide reference and experience for the future similar projects.

Against the backdrop of increasing demands for the safety and longevity of the bridge infrastructure, this review synthesizes the recent advances in structural health monitoring (SHM) sensing systems. Carbon nanotube (CNT), piezoelectric, RFID, wireless, fiber optic, and computer-vision-based sensing are thoroughly explored and elucidated in the existing literature survey that distills their working principles, documented deployments, and anticipated research directions. CNT sensors detect minute resistance variations for strain and crack surveillance; piezoelectric devices transduce mechanical stimuli into high-resolution electrical signals; RFID tags combine location tracking with modular sensing and wireless data relay; and wireless sensing technology integrates sensor nodes with microprocessors and communication modules, which can facilitate efficient data processing and autonomous management. Fiber optic sensing technology, known for precision and interference resistance, is ideal for high-precision monitoring under strong electromagnetic interference conditions, and vision-based systems emulate human perception to extract geometric descriptors via image analytics. The comparative analysis reveals complementary strengths that guide practitioners in selecting optimal sensor suites for specific bridge conditions. The findings underscore the transformative role of these technologies in enhancing SHM reliability and suggest that synergistic integration with robotics and emerging materials will further advance future resilient monitoring frameworks.

The mechanical behavior of the steel–concrete joints in a composite bridge was investigated. Pull-out tests on eight specimens were carried out to evaluate the connection performance of Perfobond rib shear connectors (PBL shear connectors). In addition, static load tests were conducted on three composite joint specimens with a scale of 1/2 in a composite truss bridge. The crack load, load–displacement curves, strain distribution, and the joint stiffness were obtained from the composite joint to analyze the mechanical behavior of steel–concrete joints. The experimental results show that the embedded depth plays an important role in the ultimate bearing capacity and the deformation of PBL shear connectors and could even change the failure mode. Based on the test results of composite joints, the displacement increased almost linearly with the horizontal load on the concrete chord. There was no evident failure, and large deformation occurred in composite joints. In addition, the ultimate loads obtained from three composite joint specimens were greater than 2.93 times the design load (2050 kN). These investigated composite joints had excellent bearing capacity (above 6000 kN). This study will provide an experimental reference for the design of steel–concrete joints for composite truss bridges.