Horizontal-Vertical Coupling of a Building Frame System in Shake Table Testing to 3D Motions
A large-scale, shake-table test program was conducted with a goal to promote rapid spread of base isolation systems in Japan and the U.S. A small steel frame building with and without base isolation was subjected to 2D and 3D shaking at E-Defense. Coupling of the horizontal and vertical response as well as high intensity slab vibration contributed to nonstructural damage in the building. Strong coupling in a configuration with triple pendulum bearings (TPB) was shown to result from the friction mechanism in the bearings. However, the source of coupling in a configuration with a hybrid isolation system (lead rubber bearings or LRB and cross-linear rolling bearings) and the fixed-base building configuration has not yet been explained.