Shaking table tests on the seismic response of bent frame supported U-shaped groove aqueduct with pile foundations considering fluid–structure interaction

As a critical lifeline project, large reinforced concrete aqueducts often traverse areas of high seismic activity, rendering them vulnerable to earthquake-induced damage. Consequently, this vulnerability can result in interruptions to water transmission and give rise to significant safety incidents. Therefore, this study investigates the nonlinear seismic response of a bent frame supported U-shaped groove aqueduct with pile foundations by shaking table tests. The results indicate that water in the aqueduct groove increases the total mass of system, reduces its natural frequency, and increases its damping ratio. As earthquake intensity rises, the sloshing amplitude of the water also increases, exhibiting strong nonlinearity. The natural vibration frequency of the aqueduct system varies significantly with changes in the water sloshing amplitude, further affecting its seismic response. For example, in the low-intensity El-Centro earthquake record, the water in the groove amplifies the acceleration response of the aqueduct system; however, in the case of the high-intensity El-Centro earthquake, the strong sloshing amplitude of the water alters the natural vibration frequency of the aqueduct system, moving it away from the frequency range corresponding to the high vibration energy of the earthquake record, thus reducing the acceleration response of the aqueduct system. It is worth noting that although the water in the groove may inhibit the acceleration response of the aqueduct in some cases, it fails to reduce the displacement and strain response of the aqueduct system. This is because the water in the groove not only increases the total mass of the aqueduct but also extends its vibration period, leading to a greater displacement response. Additionally, the hydrodynamic pressure on the aqueduct groove inside wall is greater than that on the groove bottom, and hydrodynamic pressure increases nonlinearly with the increase of earthquake intensity. The findings of this study provide valuable test data for the seismic design and seismic response analysis of aqueducts with pile foundations.