Whole-of-Building Approach to Improve Seismic Retrofits of Reinforced Concrete Buildings in New Zealand

• Authors: L. Hogan, R. Kuwabara, M. Millen, G. Munoz, W. Pollalis, S. Pujol, J. Rincon, A. Shegay
• Date: 8 May 2024
• Contract Reference: 3341

Abstract

In response to the pressing need for retrofit guidelines in New Zealand identified by the Building Innovation Partnership (BIP), Toka Tū Ake, and the Joint Committee on Seismic Assessment of Existing Buildings (JCSAEB), an effort has been initiated to develop a retrofit guide for existing reinforced concrete (RC) multi-storey buildings. New Zealand's unique construction practices, such as the combination of precast and cast-in-place RC and the use of structural systems with limited stiffness, create specific challenges for seismic retrofitting that cannot necessarily be addressed using existing international practices. Furthermore, current overemphasis on the vulnerability index known as 'percent new building standard' (%NBS) has led to issues such as retrofit schemes overlooking essential components, inconsistent vulnerability estimates, disputes, unnecessary expenses, and solutions that may not address critical deficiencies.

The objective of the proposed guide is to address the critical need to assist engineers in (a) prioritising vulnerabilities in existing buildings, (b) ensuring compliance with standards, and (c) adopting new knowledge and improvements in retrofit practices. Workshops held in 2023 and a literature review conducted in 2024 identified challenges and opportunities associated with retrofitting buildings in New Zealand. In response, this white paper proposes solutions to some of the identified challenges, which may be explored in the development of the proposed retrofit guide.