Applied seismic retrofit: experiences from Canada and New Zealand

Overview

The event will comprise two talks, from speakers in Ottawa, Canada and Christchurch, New Zealand. 

First talk:

The first talk will discuss seismic retrofit of Centre Block, Canada’s heritage designated federal parliament building located on Parliament Hill, Ottawa. It was constructed in 1916 after fire destroyed an earlier building of the same name that occupied the site. The building, and its iconic 92m tall Peace Tower, is currently undergoing a major rehabilitation that includes conservation of its heritage fabric, modernisation of its mechanical and electrical systems, enclosure of its interior light courts with glass roofs, the addition of a large multi-level below grade Parliament Welcome Centre, and a comprehensive seismic upgrade.

The seismic upgrade is particularly complex due to the historic materials used in Centre Block’s construction and the heritage finishes that adorn its walls, floors, and ceilings. At the schematic design level, two general upgrade approaches were explored: a conventional seismic upgrade and an upgrade incorporating seismic isolation. Although not commonly used in moderate seismic zones, the upgrade incorporating seismic isolation was found to be highly effective, less intrusive and to provide a greater level of protection to the building and its finishes.  

The speaker will provide an overview of the existing building and its historic construction materials, and discuss a summary of its current seismic performance level, key vulnerabilities, and goals of its seismic upgrade. Key decisions relating to the seismic isolation system design and superstructure strengthening will be explained.

Second talk:

The second talk will discuss practical experiences and learnings from various retrofit projects in New Zealand. The focus of the talk will be how adaptive reuse of existing buildings can be one of the most significant contributions to climate change reduction that an individual structural engineer can make. However, in seismic regions, many older buildings were designed before the introduction of seismic standards, and their assessment and retrofit is a complex engineering problem.

The talk will discuss the approach to seismic retrofit of existing buildings in New Zealand.  It will cover the introduction of a standardised, regulated, assessment system.  This will include the consequences of a uniform ‘scoring’ system for structures that have made conversations with structural engineers much more accessible to the general public, highlighting both the benefits of such a system and some of its unintended consequences.

It will also discuss how the New Zealand engineering industry – and the New Zealand public – have handled changes to engineering knowledge in such an environment, considering changes in both the National Seismic Hazard Model and some unexpected deficiencies in commonly used forms of construction.