2019 CSCE Annual Conference - Laval (Greater Montreal)

2019 CSCE Annual Conference - Laval (Greater Montreal) Conference


Title
Characterisation of residential buildings made of unreinforced brick masonry and planked timber walls in Montreal for seismic risk studies.

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Author(s)
Mr. Mohamed Hassem Kraiem, École de technologie supérieure (Presenter)
Dr. Nollet Marie-José, École de technologie supérieure
Mr. Antoine Gendron, École de technologie supérieure
Dr. Luc Chouinard, McGill University
Abstract

A recent seismic risk inventory of existing building stock in Montreal Island showed that wood frame structures constitute 83% of the total number of buildings followed by unreinforced masonry (URM) buildings with 14%. Several of those buildings built between 1860 and 1950 in the central sectors of Montreal are mixed structural systems consisting of unreinforced masonry walls and wood framing. This type of residential structure is not specifically considered in the building classification defined in neither the Canadian nor American version of Hazus software used for seismic risk assessment studies.  The main objective of this research is to provide information about the materials, structural systems and dynamic characteristics of residential buildings, built in Montreal between 1875 and 1950.

Two different types of structures are studied in this project. They are generally incorporated in a row of buildings, two or three stories high, with individual units separated by a common unreinforced brick firewall. The first type of building consists of URM external bearing walls, with an interior wood frame structure supported on the URM bearing walls or the firewalls. For the second type of building, the interior wood frame structure is supported on façade walls made of planked timber. The planked timber walls are typically made of white pine planks with a cross-section of three by eight to twenty-four inches.

The structural characterization of typical buildings was conducted through visual inspections of buildings undergoing rehabilitation and through a literature review on the history of residential construction and architecture in Montreal. The structural characterization consists of information on construction material, the composition and dimensions of the roof, walls, floors and foundations, as well as details on connexions between elements and between the wood and masonry systems, bearing walls or brick veneers.

Ambient vibration measurements were used for the dynamic characterization of the buildings. Measurements were,  recorded using four high resolution tromographs (Tromino©). Data was analyzed to obtain the fundamental periods, mode shapes and damping of the structures using the Enhanced Frequency Domaine Decomposition method (EFDD) and the Frequency Domain Decomposition method (FDD). Ambient vibration measurements were also conducted on site, to obtain the ground frequency resonance using the horizontal over vertical spectral ratio method (HVSR).

The collected data will be used to develop and calibrate models for the evaluation of the lateral resistance and fragility analysis of these buildings.