Toggle-brace-damper seismic energy dissipation systems

Energy dissipation systems are being increasingly employed in the United States to provide enhanced seismic protection for new and retrofit building and bridge construction. The hardware utilized includes yielding steel devices, friction devices, viscoelastic solid devices, and mostly, so far, fluid viscous devices. This hardware has been used in either diagonal or chevron brace configurations. This paper presents three new configurations that utilize toggle-brace mechanisms to substantially magnify the effect of damping devices so that they can be utilized effectively in applications of small structural drift. Shake table testing of a large scale steel model structure and analysis are used to demonstrate the utility of these configurations. The experimental results demonstrate substantial increases in the damping ratio despite the use of small size damping devices, and, accordingly, significant attenuation of the seismic response of the tested stiff structure is observed. Moreover, the experimental results are found to be consistent with analytical predictions based on either simplified methods or response history analysis. Applications of the new configurations are briefly described.