Published: 9th U.S. National and 10th Canadian Conference on Earthquake Engineering, 2010
This paper presents design examples of frame and wall buildings that use mode-shaping spines to control drift by ensuring a global tilting mode while precluding story mechanisms. The improvements to seismic performance are significant and cost-effective with several projects achieving savings in comparison to conventional systems. Performance Based Design frees designers from the constraints of a force-based code. This allows the synthesis of the overall project goals – the improvement of seismic resistance, the reduction of first costs, the protection of architectural skin, and the reduction of damage and loss of use.
In addition to mode-shaping deformation control, several examples employ rocking and re-alignment strategies. A cantilever wall with a flexural mechanism at its base is an obvious example. Rocking steel frames and mast frame examples are also presented. Restoring force characteristics are provided in the form of post-tensioning reinforcement to re-align buildings back to plumb after an earthquake.