Large-scale shaking table test of steel braced frame with controlled rocking and energy dissipating fuses (original) (raw)

Research and experience from past earthquakes suggest the need for buildings that are less vulnerable to damage and easier to repair after a major earthquake. Of particular concern are certain conventional systems, such as concentrically braced steel frame buildings, whose design may rely on more inelastic energy dissipation than the systems can provide. Our research aims to develop a new structural system that employs controlled frame rocking action and replaceable structural fuses to provide safe and cost effective resistance to earthquakes. The system combines desirable aspects of conventional steel-braced framing with energy dissipating shear fuses that are mobilized through rocking action. Vertical post-tensioning is provided to increase over-turning resistance and enhance the self-centering characteristics of the system. This paper describes the planning, design, and preliminary results of a two-thirds scale rocking braced frame tested on the E-Defense facility in Japan. The test specimen consists of a planar frame that was sandwiched between to "testbed" structures that supported the seismic mass and provided out-of-plane stability. Tests of the system under multiple ground motions and four alternative fuse designs demonstrate the robustness of the system to sustain ground motions in excess of the Maximum Considered Earthquake motions without damage.