SEISMIC RESPONSE BEHAVIOR AND SHAKING TABLE TESTS ON FREESTANDING VASE

Earthquake damage to freestanding nonstructural components has occurred in past earthquakes. Ceramic vase is one of the most vulnerable freestanding nonstructural components especially in museums and historical buildings. The vase is commonly placed on the floor without any mechanical attachment between the floor and its bottom. Under the action of friction force, there are basically four types of response mode, i.e., rest, slide, slide-rock, and rock. These kinetic behaviors are determined by friction coefficients and floor motions. Shaking table testing is conducted to understand the seismic behavior of freestanding vase, where four representative motions, consisting of two historic and two artificial ones, are selected and generated. Marble stone panel is fixed on the surface of the shaking table to simulate the floor, which is very popular in modern residential and office buildings. The kinetic friction coefficient is acquired with a slow-pull test, used to define the possible response modes. The rocking and sliding responses of the vase are observed by accelerometers and high-speed camera. The results show that: the response mode of the vase is highly dependent on the input peak acceleration, i.e., the higher the peak acceleration, the larger the rocking angles. In addition, the dynamic response varies with the excitation of different input motions, indicating that the frequency contents of the input motion also affect the rocking intensity and that the dynamic response of AC156 is larger than that of El Centro. It is also found that the ratio of the acceleration at the center of gravity to the local gravitational acceleration is equal to the kinetic friction coefficient in the test. The experimental and closed form theoretical analysis results were generally agreed with each other.