High-rise pile cap structures, such as sea-crossing bridges, suffer from long-term degradation due to continuous corrosion and scour, which seriously endangers structural safety. However, there is a lack of research on this topic. This study focused on the long-term performance and dynamic response of bridge pile foundations, considering scour and corrosion effects. A refined modeling method for bridge pile foundations, considering scour-induced damage and corrosion-induced degradation, was developed by adjusting nonlinear soil springs and material properties. Furthermore, hydrodynamic characteristics and long-term performance, including hydrodynamic phenomena, wave force, energy, displacement, stress, and acceleration responses, were investigated through fluid-structure coupling analysis and pile-soil interactions. The results show that the horizontal wave forces acting on the high-rise pile cap are greater than the vertical wave forces, with the most severe wave-induced damage occurring in the wave splash zone. Steel and concrete degradation in the wave splash zone typically occurs sooner than in the atmospheric zone. The total energy of the structure at each moment under load is equal to the sum of internal energy and kinetic energy. Increased corrosion time and scour depth result in increased displacement and stress at the pile cap connection. The long-term dynamic response is mainly influenced by the second-order frequency (62 Hz).

In recent years, the escalation in accidental explosions has emerged as a formidable threat to tunnel infrastructures. Therefore, it is of great significance to conduct a dynamic performance analysis of the tunnels, to improve the safety and maintain the functionality of underground transport hubs. To this end, this study proposes a dynamic performance assessment framework to assess the extent of damage of shallow buried circular tunnels under explosion hazards. First, the nonlinear dynamic finite element numerical model of soil-tunnel interaction system under explosion hazard was established and validated. Then, based on the validated numerical model, an explosion intensity (EI) considering both explosion equivalent and relative distance was used to further analyze the dynamic response characteristics under typical explosion conditions. Finally, this study further explored the influence of the integrity and strength of the surrounding soil, concrete strength, lining thickness, rebar strength, and rebar rate on the tunnel dynamic performance. Our results show that the dynamic performance assessment framework proposed for shallow circular tunnels fully integrates the coupling effects of explosion equivalent and distance, and is able to accurately measure the degree of damage sustained by these structures under different EI. This work contributes to designing and managing tunnels and underground transport networks based on dynamic performance, thereby facilitating decision-making and efficient allocation of resources by consultants, operators, and stakeholders.

The safety and reliability of wind turbines subjected to multiple loads has recently attracted great attention. To investigate how soil-structure interaction (SSI) affects the seismic performance of operating wind turbines, a wind tunnel-shaking table test platform has been built which can realize applying wind load and seismic load simultaneously. A 1:100-scaled wind turbine model with two different kinds of foundations (soil-structure interactive foundation and rigid foundation) has been tested under four seismic excitations (El-Centro and Taft, input in two directions) when it keeps operating in wind excitations. Nacelle displacement with the soil-structure interactive foundation was significantly larger than that of the rigid foundation, reaching 3-5 times at a peak ground acceleration (PGA) of 0.8 g. The maximum nacelle displacement of the scaled model with soil-structure interactive foundation always occurs in the direction of incoming wind, unlike the rigid one occurring in the direction of seismic input direction. The rigid foundation model presents a strong whipping effect with an acceleration amplification factor of the tower top (APF = 3). In contrast, the model with soil-structure interactive foundation shows mild whipping effect due to smaller foundation stiffness (APF of the tower top = 1.5). The study demonstrates SSI could weaken dynamic responses, reducing bending moments but inducing excessive nacelle displacement, risking structural damage. This study underscores the importance of SSI in evaluating the safety and reliability of wind turbines subjected to the wind and seismic loads and provides experimental results for future designs.