Full-scaled shaking table test of a hospital made of a base-isolated four-story concrete structure

A series of full-scale shaking table tests are conducted using the E-Defense shaking table facility on a base-isolated four-story concrete structure that is intended to serve as a hospital building. Four ground motions are adopted, including synthesized long-period and long-duration ground motions. The results show that the base isolation system performed very effectively against near-fault ground motions. The operability and functionality of hospital service is improved significantly as compared to the corresponding base-fixed system, because the acceleration responses were alleviated greatly. Against long-period ground motion, however, maintaining the hospital service is found not to be easy mainly because of significant motion of furniture and appliances equipped with casters. Resonance accentuated large displacements and velocity in the base isolation floor, which causes large amount of sliding to the furniture with casters, sometimes resulting in collision with other furniture. It is noted that a key to maintain the function of the medical facilities is to lock the casters securely.