The MBIE Seismic Assessment of Existing Buildings provides the technical basis for engineers to carry out seismic assessments of existing buildings in Aotearoa New Zealand. They are designed to support seismic assessments for a range of purposes, including whether a building is earthquake prone in terms of the Building Act 2004,and more generally for property risk identification.
Specifically, these guidelines provide the assessment component of the earthquake-prone building (EPB) regulations and EPB methodology that came into force on 1 July 2017. It is mandatory that these guidelines are now adhered to for all engineering assessments that territorial authorities may use to determine whether a building is earthquake prone or not, with defined assessment and reporting procedures to be followed.
The guidelines issued July 2017, known as the ‘Red Book’, contained a number of errors which, when combined with some more up-to-date learnings regarding precast floors, saw an updated Concrete Buildings C5 –Technical Proposal to Revise the Engineering Assessment Guidelines released in November 2018, which is known as the ‘Yellow Book’.
CLIENT BRIEF/PROJECT CHALLENGES
The Red Book (the use of which is legislated) and the Yellow Book (containing the most current assessment guidelines) sit somewhat awkwardly side by side, with both potentially being used for the same building. In 2019 MBIE commenced a package of works to increase their understanding of the differences between the results generated by the Red and Yellow books.
MBIE engaged several consultancy firms, including WSP, to conduct parallel seismic assessments on representative buildings to compare the results between these two methodologies.
The scope of works for WSP was to conduct Detailed Seismic Assessments on numerous buildings located across the country. Buildings were selected to cover a range of seismicity, construction type and building arrangements i.e. shear wall buildings and moment-frame buildings were both assessed, in combinations of both low-rise and high-rise.
WSP Structural Engineers observed the introduction of the first national building codes and standards and have contributed to the codes and standards used today. Will Parker, WSP Technical Director Property and Buildings,is co-author of industry guidelines for the seismic assessment of base isolated buildings. Carl Ashby, WSP Structures Director,is part of the SESOC working group that has published industry guidelines on the assessment of precast flooring units.
This engagement shows that WSP continues to play a keyrole in the development of structural codes and seismic assessment guidelines, which ultimately benefits the entire engineering industry.