General Contractor

Solar Restoration

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Project Consultant

WSP

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Year

2023

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Location

Toronto, Canada

Our Role

We were brought in to help design, fabricate, and install structural reinforcing to the heavily deteriorated beams and columns of an existing apartment building.  

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Project Background

The project, initially set out with straightforward objectives of re-roofing and minor concrete repairs above and within an adjoining above-grade parking garage, encountered unexpected challenges during its demolition phase. What was anticipated to be routine quickly escalated as the team uncovered extensive structural degradation of critical building superstructure elements including main building support columns, posing an immediate risk to property and life safety. Consequently, this discovery necessitated a shift from the planned project to an urgent and comprehensive structural rehabilitation effort. The project's scope expanded dramatically, demanding advanced solutions and interventions to address the now-evident risks and ensure the structural integrity and safety of the mid-rise apartment building. 

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Project Description

After the Engineer of Record outlined a preliminary repair methodology and design intent, our team became deeply involved in its refinement, utilizing our expertise in welding processes, metallurgy, and techniques to finalize the repair design details. This collaborative effort led to the development of web and flange reinforcement sub-weldments which could be pre-fabricated in our shop. By segmenting the work in this way we significantly accelerated the repair process. To further accelerate the repair schedule we chose a gas-shielded FCAW (Flux-Cored Arc Welding) process for the remainder of the field welding due to its inherent speed, all-position welding capability, and low hydrogen classification, enhancing onsite welding efficiency by approximately 200-300% over traditional methods.

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The project, undertaken during winter months, necessitated extensive pre-heating of materials in line with our detailed welding procedures. This step was critical to achieving the desired mechanical properties of the welds, especially important for welds critical to structural integrity.

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In designing the repairs, special attention was given to the potential impact of heat input from transverse welding across column flanges and webs, which could significantly diminish the existing structure's load-bearing capacity. To mitigate this, our welding procedures also employed a strategy of breaking down transverse weld lengths into a series of partial length welds, which would be allowed to cool to specified inter-pass temperatures, in order to maintain as low a temperature as possible across the structural members.

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The execution of these carefully planned repairs not only restored the structural integrity and immediate safety of the building but also ensured its longevity and serviceability for many years to come.