Date of Award

Fall 2021

Publication Type

Thesis

Degree Name

M.A.Sc.

Department

Civil and Environmental Engineering

Keywords

Experimental testing, Lag screw, Shelf angles, Thermal performance, Through-bolt

Supervisor

B. Balasingam

Supervisor

N. Van Engelen

Rights

info:eu-repo/semantics/openAccess

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Abstract

Recent legislations are demanding more efficient thermal insulation of the building envelopes. However, most of the energy used for heating is lost through openings and small air gaps resulting from various penetrations of highly conductive elements through the building envelope. These thermal bridges can also give rise to mould growth and condensation problems. One such example is the anchoring of shelf angles to the load bearing structures, as they have to cut through the exterior insulation used to enhance the thermal performance of a building envelope.

Steel through-bolts have been conventionally used by the construction industry to anchor shelf angles to a wooden frame system; however, these fasteners are uneconomical, time-consuming, and poor thermal performers, as they have to penetrate the building envelope. This research program was designed to investigate lag screws as an alternative fastener to anchor shelf angles to wooden frame structures, along with different stand-offs to further enhance the thermal performance of the building envelope. This research program comprises of both lab-based experimental work to evaluate the structural performance of these connections, and a 2-D finite element analysis of their thermal performance.

The thermal analysis reveals that though-bolt connections exhibited poor thermal performance among all the connections investigated in this study. While the lag screws helped in truncating the heat flow of the thermal bridge formed in the through-bolt connection. Additionally, it was found that through-bolts had higher load capacity per fastener than lag screws since the through-bolts had a longer embedment length. It was also found that failure mode of through-bolt specimens caused them to experience more mid-span deflection and rotation. Various stand-offs with better thermal performance were also investigated. Specimens with steel C-channel stand-offs exhibited a better structural performance than the fiberglass stand-offs.

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