Thesis Format
Integrated Article
Degree
Doctor of Philosophy
Program
Civil and Environmental Engineering
Supervisor
Kopp, Gregory A.
2nd Supervisor
El Ansary, Ayman M.
Co-Supervisor
Abstract
High-wind events cause significant damage to structures and property; in particular, light-frame wood homes are abundant and especially vulnerable. Canadian homes are built to prescriptive standards that are based on historical construction methods and have remained relatively unchanged structurally across several decades. While recent work is contributing to improving building codes and providing voluntary standards for improving wind resilience of houses in Canada, there exists a gap in understanding of structural behaviour of light-frame buildings. Such an understanding would help to bridge the difference between conservative, fully-engineered solutions and slowly-evolving prescriptive solutions which are based on observed performance of houses from years past. With increasing extreme weather events, and drastic changes in the typical house design since the inception of the building code, there is a need for methodology to better understand and make use of the realistic structural behaviour of houses exposed to high winds.
This thesis presents a comprehensive assessment of light-frame Canadian homes constructed to current prescriptive standards and their potential to withstand high winds. The focus of this research is to improve the understanding of the vertical load path through houses built to the current NBC Part 9 provisions. First, engineering calculations are applied to estimate the uplift resistance of certain links in the vertical load path in order to identify provisions in Part 9 that would not meet the structural design requirements of Part 4, or even less-conservative versions where load and resistance factors are removed. The weak links are then proven using field observations and forensic assessment of wind-damaged buildings. To quantify the behaviour of light-frame roofs under realistic wind uplift, full-scale experimental results and finite element modelling are combined. A full-scale experimental data set is utilized for examination of load transfer, and a non-linear finite element modelling approach is developed to estimate wind speeds causing failure of the archetype roof. This work proves the concept of load redistribution through light-frame, trussed roofs under wind uplift and identifies a distinct tendency for the gable end truss to carry a large proportion of roof uplift. A number of design alternatives are developed, modelled, and compared in order to identify solutions that would make efficient use of the load sharing behaviour of gable roofs and improve their resistance to high wind loads.
Summary for Lay Audience
High-wind events cause significant damage to structures and property; in particular, light-frame wood homes are abundant and especially vulnerable. Canadian homes are built to prescriptive standards that are based on historical construction methods and have remained relatively unchanged structurally across several decades. While recent work is contributing to improving building codes and providing voluntary standards for improving wind resilience of houses in Canada, there exists a gap in understanding of structural behaviour of light-frame buildings. With increasing extreme weather events, and drastic changes in the typical house design since the inception of the building code, there is a need for methodology to better understand and make use of the realistic structural behaviour of houses exposed to high winds.
This thesis presents a comprehensive assessment of light-frame Canadian homes constructed to current prescriptive standards and their potential to withstand high winds. The focus of this research is to improve the understanding of the vertical load path through houses built to the current NBC Part 9 provisions. Forensic observations and engineering calculations are used to identify common weak links, and a full-scale experimental data set is utilized for examination of load transfer. A non-linear finite element modelling approach is developed to estimate wind speeds causing failure an the archetype roof. A number of design alternatives are developed, modelled, and compared in order to identify solutions that would make efficient use of load sharing behaviour of roofs and improve their resistance to high wind loads.
Recommended Citation
Stevenson, Sarah A., "Performance Assessment and Development of Prescriptive Design Standards for Wood-Frame Residential Structures Under Extreme Wind Loads" (2023). Electronic Thesis and Dissertation Repository. 9826.
https://ir.lib.uwo.ca/etd/9826
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