Track 2: DESIGN - PLANNING THE CONSERVATION OF HISTORIC PLACES / Volet 2 : Conception - Planifier la conservation de lieux historiques

Ottawa’s Heritage Masonry Buildings - Developing Seismic Retrofit Options

Friday, October 13
8:30 AM - 10:00 AM

The nation's capital is famously home to the East, West, and Centre blocks on Parliament Hill. Each of those is, or will be undergoing a significant rehabilitation project that will include an upgrade to the building's seismic performance with a major retrofit. However, the capital is also home to a large number of other heritage, high-profile, high-quality, and publicly owned structures, built between the turn of the last century and the beginning of the second world war. Many of these buildings, either impacted by the disruption from the work on the Hill or for their own reasons, have or will be renovated and rehabilitated.

Ottawa is also fortunate (at least for a structural engineer) to be one of the most significant populated seismic areas in Canada. While it is no Vancouver, given Ottawa's sizeable inventory of historic masonry structures, seismic risk is an important consideration in any rehabiliation project. A reminder of this fact occured in 2010, with an earthquake many times weaker than that described in the National Building Code, but which was certainly sufficient to get everyone's attention.

Introducing a seismic retrofit into a building which is high-profile, has high heritage value, is potentially occupied, and was built without the slightest thought about seismic design, all for a complex client, brings with it a unique set of challenges. This paper will discuss some of these challenges and our philosophy and approach to solving them.

The paper will cover the project initiation and context, such as why the building is being rehabilitated and who is asking for a seismic upgrade. The investigation and feasibility phase of the work will be covered, including the impact and importance of determining key construction details and of the existing structural system, as well as the challenges of completing investigation and testing work in occupied government buildings.

Typical behaviour of unreinforced masonry structures with a historic steel or concrete frame will be described. Analytical modeling techniques for such buildings, including modeling assumptions and their impact, and sensitivity analysis and bracketing techniques will be covered.

The process of selecting a retrofit approach and its potential impact on heritage fabric will be discussed, as well as the principles of limited intervention and reversibility. The limitations imposed by the unreinforced masonry cladding will be considered, as will the selection of an upgrade that is compatible with the existing structure and its components. The paper will illustrate the kitchen sink versus selective approach to Non-Structural building components, especially those with heritage fabric, and some potential retrofit options.

The paper will include real-life examples, including a description of the work at the Government Conference Centre, Postal Station B (formerly the Central Post Office), and the Confederation Building.

Learning Objectives:

Jonathan Dee, P.Eng., ing.

Project Engineer, Associate
John G. Cooke & Associates Ltd.

Jonathan Dee is a Project Structural Engineer and Associate at John G. Cooke & Associates Ltd., having started there after graduating from the University of Ottawa in 2007.

Jonathan is responsible for providing structural engineering services from feasibility studies through to construction review and contract administration. He has experience completing masonry conservation projects such as the Royal Bank of Canada Headquarters in Old Montreal, rehabilitation and adaptive re-use projects such as the Bank of Montreal Rehabilitation, and seismic analysis, such as the Postal Station B Rehabilitation.

Jonathan also represents Construction Specifications Canada at the Institute for BIM in Canada.

Presentation(s):

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