Rock On! Advancing seismic resilience using controlled rocking

Overview

As seismic design increasingly emphasises not only safety but also community resilience, engineers are seeking structural systems that can efficiently achieve enhanced performance objectives.

Controlled rocking systems offer one such solution: simply by allowing targeted structural elements to uplift from the foundation under large lateral loads, peak seismic forces are limited in a way that avoids structural damage and residual deformations.

This rocking behaviour can then be controlled using post-tensioning and/or energy dissipation. 

This seminar will draw on examples from both research and practice to illustrate the opportunities and challenges of implementing controlled rocking in steel, mass timber, and reinforced masonry.

While each material requires unique detailing considerations at the rocking interface and the diaphragm connections, their global dynamic response is remarkably similar.

Key design challenges include: (1) peak displacements that often exceed the equal displacement assumption, and (2) higher mode effects that reduce the ability of rocking to limit the internal forces.

The seminar will introduce easy design tools that allow engineers to predict these effects without nonlinear analysis, allowing the benefits of controlled rocking to be harnessed while keeping the design process as simple as for other common seismic force resisting systems.

Attendees will learn about not only the structural behaviour of controlled rocking systems, but also how these systems affect the demands on non-structural components, including comparisons with other seismic force resisting systems in terms of expected seismic losses.

The seminar will conclude with an overview of the current state of prescriptive design requirements and codification.