The Earthquake Engineering Online Archive

Seismic behavior of an eccentrically X-braced steel structure

Yang, Ming-San

UCB/EERC-82/14, Earthquake Engineering Research Center, University of California, Berkeley, 1982-09-01, 264 pages (530/Y32/1982)

A five-story, one-third-scale model structure weighing about 50 tons was tested on the shaking table at the Earthquake Engineering Research Center, U.C. Berkeley, to study the earthquake-resistant characteristics of an eccentrically X-braced structure. The eccentric bracing was created by a deliberate introduction of offsets into the brace-beam connections. The eccentric beams, designated shear links, yielded mainly in shear. Three sets of shear links, designed to be replaceable, were sequentially installed in the structure and tested to destruction. The experimental results indicated that the eccentrically X-braced test structure could efficiently resist an El Centro-type motion with a peak acceleration of 1.15 g; a ductility factor of about 100 was recorded for shear yielding of links. It was observed that the earthquake response was strongly correlated with the strength in the links and that the weakest link was the best energy dissipator. A simplified mathematical mode was formulated for data correlation. To reduce the number of unknowns in the model, the upper three elastic stories were replaced by an equivalent shear story; the shear yielding behavior was modeled by vertical truss elements.

Available online: http://nisee.berkeley.edu/documents/EERC/EERC-82-14.pdf (50 MB)