Bridge strikes by over-height vehicles or ships are critical sudden events. Due to their unpredictable nature, many events go unnoticed or unreported, but they can induce structural failures or hidden damage that accelerates the bridge’s long-term degradation. Therefore, always-on monitoring is essential for deployed systems to enhance bridge safety through the reliable detection of such events and the rapid assessment of bridge conditions. Traditional bridge monitoring systems using wired sensors are too expensive for widespread implementation, mainly due to their significant installation cost. In this paper, an intelligent wireless monitoring system is developed as a cost-effective solution. It employs ultralow-power, event-triggered wireless sensor prototypes, which enables on-demand, high-fidelity sensing without missing unpredictable impact events. Furthermore, the proposed system adopts a smart artificial intelligence (AI)-based framework for rapid bridge assessment by utilizing artificial neural networks. Specifically, it can identify the impact location and estimate the peak force and impulse of impacts. The obtained impact information is used to provide early estimation of bridge conditions, allowing the bridge engineers to prioritize resource allocation for the timely inspection of the more severe impacts. The performance of the proposed monitoring system is demonstrated through a full-scale field test. The test results show that the developed system can capture the onset of bridge impacts, provide high-quality synchronized data, and offer a rapid damage assessment of bridges under impact events, achieving the error of around 2 m in impact localization, 1 kN for peak force estimation, and 0.01 kN·s for impulse estimation. Long-term deployment is planned in the future to demonstrate its reliability for real-life impact events.

Steel–concrete composite decks are commonly employed in narrow-width steel box composite girder bridges to augment their lateral spanning capabilities, while the concurrent omission of longitudinal stiffeners leads to a substantial reduction in the number of components, thereby yielding a structurally optimized bridge configuration. This paper delineates the structural design parameters of a narrow-profile steel box composite girder bridge and assess the mechanical behavior of its incorporated steel–concrete composite deck under static and fatigue loading conditions. To this end, two full-scale segment specimens from the composite bridge decks were subjected to equal amplitude cyclic fatigue tests. The investigation specifically concentrated on the impacts of two types of shear connectors—namely, perforated steel plates combined with shear studs and perfobond rib shear connectors (PBL connectors)—on the static and fatigue performance, including fatigue stiffness, of the steel–concrete composite bridge decks. The results indicate that, under the static bending condition, the composite deck specimen equipped with stud connectors demonstrates superior overall flexural stiffness in comparison to the specimen featuring PBL connectors. Furthermore, the flexural stiffness of the steel–concrete composite specimens experiences a negligible alteration across two million fatigue loading cycles. Upon the completion of two million fatigue loading cycles, the composite deck specimens incorporating the shear connectors composed of perforated steel plates and shear studs exhibit relatively wider crack widths under the static peak load. Both configurations of the steel–concrete composite bridge deck specimens manifest evident interfacial detachment, signifying insufficient tensile pull-out stiffness of the shear connectors. It is recommended to increase the quantity of the shear connectors or select the pertinent types in order to enhance the interface shear resistance.

This paper presents a proposed static test and numerical study on the mechanical properties of steel-shell–concrete-structure-immersed tunnel nodes, which is used to investigate the seismic performance and damage mechanism of steel-shell–concrete-structure-immersed tunnel nodes. The test is based on the immersed tube tunnel project in the deep China channel, and the nodes representing the outermost and innermost vertical walls of the immersed tube tunnel, i.e., L-shaped and T-shaped node specimens, were designed and fabricated at a scale of 1:5, and the specimens were mainly subjected to the combined effect of vertical axial compression and lateral displacement loads. The test results show that the L-shaped node will exhibit brittle damage characteristics with high lateral load carrying capacity and energy dissipation capacity during the ultimate load phase, while the T-shaped node exhibits bending damage with better ductility, so the outermost vertical wall should be locally reinforced to ensure the necessary ductility of the structure in the actual project. In addition, by comparing the numerical calculation and experimental results, it is found that there is good agreement in terms of load–displacement curves and crack distribution, which shows that the modeling method proposed in this paper can accurately simulate the mechanical properties of immersed tunnel nodes and can guide the section design of immersed tunnels with steel shell–concrete structures.

To investigate the maintenance effect of diaphragm-to-rib fatigue cracks via steel plate reinforcement, finite element models of different-shaped steel plates were established. Stress intensity factors at the crack tip before and after reinforcement were obtained, and the variations in stresses were studied. Polygonal steel plate reinforcements were then carried out on a real bridge based on the finite element calculation results. The changes in stress amplitudes and fatigue damage degrees at the crack tip were analyzed via the rain-flow counting method and Miner’s linear damage accumulating theory. The results show that both the polygonal steel plate and the rectangular steel plate could effectively eliminate the stress concentration and restrain the propagation of cracks. The stresses in other parts of the arc notch increased after reinforcement and polygonal steel plates had less influence. After the reinforcement in a real bridge, the cycle number of high stress amplitudes at the crack tip decreased significantly. The fatigue damage degree of the repaired part reduced by 70.1%, which verified the maintenance effect via polygonal steel plate reinforcement on diaphragm-to-rib fatigue cracks.

Direct vehicle impacts on stay cables are less understood than vehicle–pier collisions, especially for anchorage damage and post-impact load transfer. This study investigates the dynamic responses of stay cables under vehicular impact through a combination of scaled physical tests. This test simulates real-world vehicle collision scenarios using an impact trolley. Two 1:5 inclined specimens (each a 19-wire galvanised steel bundle) were tested using a 1582 kg impact trolley travelling at 4.0 m/s in lateral and frontal conditions. Both tests showed a rapid rise in force to a dominant peak, followed by rebound oscillations and a long-tail decay, with no wire rupture. The lateral impact force peaked at around 241 kN at a displacement of approximately 230 mm. It then declined sharply while the deflection increased to around 268 mm, indicating that large deflections were governed by inertia. In contrast, the frontal impact force reached a maximum of almost 258 kN at a displacement of around 221 mm. However, it maintained higher post-peak forces, reaching approximately 106 kN at around 253 mm. This resulted in enhanced energy transfer. Maximum external work increased from about 20.7 kJ to about 25.2 kJ, and residual energy rose from about 25 percent to about 69 percent. Post-test inspection identified minor debonding near the anchorage exit as a vulnerability.