Shaking table test of tuned damped aqueducts with a water-passing barrier
[Objective]Under transverse earthquake excitation,a water body in a large-scale aqueduct experiences evident vibration,which amplifies the seismic response of the aqueduct.This study proposes a water-passing barrier specifically designed for large-scale aqueducts to mitigate water vibration in the transverse direction.The water-passing barrier is strategically installed in the central line in the aqueduct along the longitudinal direction to divide the water body.The holes are reserved on the water-passing barrier that facilitates the passage of water during water vibration,thereby altering the vibration characteristics of the water body.By inducing water spin,it is possible to dissipate the vibration energy of the water body,ultimately leading to changes in the overall dynamic features of the aqueduct and a reduction in the overall seismic response of the aqueduct.[Methods]To investigate the effectiveness of water-passing barriers for vibration control in aqueducts,shaking table tests were conducted on typical large-scale aqueducts with rectangular and U-shaped sections.Various parameters,including the water height in the aqueduct,the permeability of the water-passing barrier,and the amplitude and frequency of the table motion,were considered during the shaking table tests.Through a comprehensive series of shaking table tests,the dynamic responses of the aqueduct were evaluated under white noise,simple harmonic load,and earthquake excitation.These responses encompass water vibration patterns,natural vibration frequency of the aqueduct,peak acceleration of the cap beam,and other structural responses.[Results]The test results indicated that water-passing barriers could enhance the table acceleration threshold for aqueduct overflow and reduce the vibration of the water body in the structure.The seismic reduction coefficient was quantified as the ratio of the peak acceleration of the cap beam in the aqueduct with a water-passing barrier to that without a water-passing barrier.The seismic reduction coefficient was influenced by various issues,such as the cross-section of the aqueduct,water level,excitation frequency,and permeability of the water-passing barrier.[Conclusions]Notably,the water-passing barrier exhibits effective response reduction performance when the excitation frequency is consistent with the fundamental frequency of the aqueduct.Nevertheless,when the excitation frequency significantly deviates from the fundamental frequency of the aqueduct,the water-passing barrier inadvertently amplifies the seismic response of the structure.When subjected to the El centro earthquake excitation,the water-passing barrier consistently exhibits satisfactory response reduction performance across most cases.However,the mean value and standard deviation of the seismic reduction coefficient are mainly influenced by the water level in the aqueduct and the permeability of the water-passing barrier.As the acceleration of the table motion increased,the water body exhibits more vigorous vibrations,leading to improved vibration reduction performance because of the water-passing barrier.Nonetheless,further investigation through more sophisticated tests and detailed analyses is necessary to establish a comprehensive understanding of the quantitative vibration control mechanism.
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