The Earthquake Engineering Online Archive

Optimal design of friction-braced frames under seismic loading

Austin, Mark A.; Pister, Karl S.

UCB/EERC-83/10, Earthquake Engineering Research Center, University of California, Berkeley, 1983-06, 97 pages (620.1/A87/1983)

This report describes the results of a multi-objective investigation. Several optimal earthquake-resistant designs are calculated for a ten-story, single-bay, friction-braced steel frame excited by a single scaled ground motion. As this was only the second major problem area to be examined with the CAD environment DELIGHT.STRUCT, a further assessment of its performance was also required. Performance is assessed on the basis of the frame's response to gravity loads only, gravity loads plus moderate earthquake, and gravity loads combined with a rare severe earthquake ground motion. A preliminary analysis was implemented to determine the performance constraints likely to become active during the optimization process. The friction-bracing was then removed and the resulting moment-resistant frame was resimulated for the same ground motion input. Approximate bounds on the performance constraints to be expected during the optimization stage were therefore obtained. A sensitivity analysis for frame response was implemented for perturbed ground motion and modeling parameters. Recommendations are given to enhance both DELIGHT.STRUCT and the design process utilized. The potential advantages of incorporating friction-bracing into steel frames are summarized.

Available online: http://nisee.berkeley.edu/documents/EERC/EERC-83-10.pdf (3 MB)