Shaking Table Test of Seismic Isolated Structures with Sliding Hydromagnetic Bearings

Abstract

The sliding hydromagnetic bearing is a low-friction isolator proposed in recent years. Its novelty lies in adaptive energy dissipation and alterable deflection constraint, which has been demonstrated by previous studies through pseudo-static tests and numerical simulations. In order to experimentally explore the effectiveness of the isolator for seismic mitigation of the base-isolated structure, a complete laboratory investigation by shaking table tests is carried out. Two sets of recorded three-dimensional and artificial one-dimensional horizontal earthquake ground accelerations pertaining to hard and soft soil sites are employed as the input to the table. The tests aim to explore the seismic mitigation of the base-isolated structure in terms of floor accelerations, interstory drifts, and horizontal torsions, as well as the seismic performance of the sliding hydromagnetic bearing in regard to oil leak prevention, deflection-resistance performance, and frictional behavior. The tests reveal that when subjected to far-field earthquake ground motions, the base-isolated structure with sliding hydromagnetic bearings exhibits a reasonable seismic mitigation of the floor accelerations and interstory drifts. In addition, it exhibits a satisfactory seismic mitigation of the horizontal torsions when subjected to either far-field or near-fault earthquake ground motions. It is also found that the workability of the sliding hydromagnetic bearing remains almost the same under different intensities of the considered earthquake ground motions. Furthermore, it is seen that the sliding hydromagnetic bearings exhibit a good oil leak prevention and deflection-resistance performance. The determined relationship between kinetic friction coefficient, bearing velocity, and axial compression in these tests reveals a similar finding in the previous pseudo-static test in that the sliding hydromagnetic bearing exhibits a shear thinning that becomes more remarkable under a larger axial compression and a higher sliding velocity.