Design and Construction of Controlled Rocking Steel Braced Frames in New Zealand

Controlled rocking steel braced frames (CRSBFs) are emerging as a promising solution for achieving an enhanced level of seismic resilience relative to traditional systems. In a CRSBF, selected columns are designed to uplift from the foundation in response to seismic loads, resulting in a reduction in lateral stiffness. This rocking action limits the maximum structural forces in a way that can avoid both residual deformations and also damage to main structural members. The response of a CRSBF can be controlled using a combination of post-tensioning and supplemental energy dissipation. This paper gives an overview of the behavior of CRSBFs before presenting three case studies of buildings that have been built in New Zealand recently. The paper introduces a New Zealand Design Guide for CRSBFs and also discusses some potential advantages and design considerations for CRSBFs in retrofit applications.