A series of seismic centrifuge tests were performed on an RC girder-type bridge with a 3 × 3 pile-group foundation embedded in dry sand to investigate the seismic behavior under various scour conditions. Based on the equivalent primary period and mass, the bridge plate was reduced to a lumped iron block supported by a single pier. The laminar shear box was excited in three earthquake events and one white noise event. The test results show that the bending moment at the pile head and the acceleration at the pile cap both increase significantly with increasing scour depth, which is a potential failure mode in practice. The maximum bending moment, which generally occurs under the soil surface at a distance of approximately 1.9–2.2 times the outer diameter of the pile, is the largest in the corner pile and the smallest in the inner pile. The results show that the maximum bending moment is augmented 63.5% at most by scour. The acceleration response and dominant frequency of the model were noticeably influenced by soil nonlinearity. However, the damping that soil in the far field provided to the bridge system considering soil–structure interaction (SSI) was negligible and has little influence on the system frequency. These observations suggested that measures should be taken to meet the bending moment demand of the pile increased by scour and provided some guidelines for the aseismic design of the bridge and a benchmark for further theory analysis.

Offshore wind power is rapidly developing as a source of clean energy. However, as local scour of the foundation of an offshore wind turbine can create serious safety risks to the normal operation of the turbine, it is necessary to protect the foundation from scour. In this paper, a new scour protection countermeasure using solidified soil has been investigated via an updated apparatus for a simplified scour resistance test (SSRT). Two types of tests were carried out: an unconfined compressive test to determine geotechnical parameters and an SSRT test to reflect the scour resistance of the soil samples. The results show that unconfined strength is approximately related to the critical flow velocity of the scour resistance as a power function. Soil samples having an unconfined compressive strength of 300 kPa can resist erosion under flow conditions above 3.14 m/s after solidification. In addition, the solidification state of the solidified soil has a great impact on the scour resistance of the soil sample, and the critical scour velocity of the final solidified soil is increased by 80–150% as compared to an initial solidified soil having the same final unconfined strength. These results suggest that attention should be paid to the state of the solidified soil during the construction process. The engineers should control the ratio of cement, water, and soil of the solidified soil according to the hydraulic parameters at the time of construction so that no great loss of solidified soil will occur during the construction process.

A simplified added-mass model is proposed in this paper for evaluating the seismic response of rectangular hollow piers in deep water, which are widely used in railway bridges. For this purpose, the accurate and concise formulas for the outer and inner hydrodynamic pressures were first derived after smoothing the pier outer surface corners by using small circular arcs. Then, the kinematic equation of the pier–water system was solved in the frequency domain and converted to the time domain with an inverse Fourier transform. In addition, the expressions for the outer and inner water added masses that were induced by elastic vibration and rigid motion were obtained. To verify the accuracy of these analytical solutions in terms of hydrodynamic pressures and added masses, a finite-element modeling approach, based on potential-based fluid elements (PBFEs), was employed to define numerical models of bridge piers in water. A comparison of the added mass coefficients induced by elastic vibration and rigid motion indicates that the former can be substituted by the latter. Meanwhile, water compressibility effects on the hydrodynamic forces have been fully discussed and proven to be negligible for general piers under most earthquakes. Finally, for convenience of application, simplified formulas for added mass and a simplified added model were presented to simulate the seismic response of rectangular hollow piers in water. The good agreement between the dynamic results from the simplified expressions and numerical method confirmed the former’s accuracy and convenience for engineering applications.