Manitoba engineer honored for fiber-reinforced concrete study

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Ehab El-Salakawy, professor of structural engineering at the University of Manitoba, won the American Concrete Institute’s 2020 Mete A. Sozen Award for Excellence in Structural Research.

The award recognizes outstanding achievement in experimental or analytical research that advances structural engineering theory or practice and recommends how the research can be applied to design.

The article has a title that most non-engineers will find terrific: Lateral Shift Deformability of GFRP-RC [glass-fiber-reinforced-polymer reinforced-concrete] Slab-to-column edge connections.

It contains a long report on the method and results of an experiment that measured the elongation of GFRP reinforcement under tensile stress, which takes place during an earthquake or other seismic event, before material failure.

The experiment compared the reactivity of concrete slab-column connections reinforced with GFRP reinforcement and steel reinforcement, respectively, during a simulated seismic event.

The simulation showed that the GFRP-RC edge connections were able to withstand seismic stresses and at the same time maintain their load capacity.

GFRP is a new type of fiber reinforced polymer (FRP).

El-Salakawy says the latter has only been used for a relatively short period – since the turn of the 21st century – as reinforcement for concrete structures.

“The main feature of FRP reinforcement is its non-corrosive nature,” he said. “Because it contains no steel, there is no corrosion, which is a major cause of deterioration of these structures and cannot be stopped.”

Since mitigating and repairing corroded reinforced concrete can be expensive, eliminating the corrodible part of the structural element increases its service life and reduces life cycle costs.

El-Salakawy says FRP reinforcement has other properties that make it attractive to the construction industry.

They include greater strength (four to five times that of ordinary steel); lighter weight (a quarter to a third of that of steel), which means lower transportation and installation costs; and electrical inertia (changes in electrical current are neutralized), which is necessary for applications such as magnetic resonance imaging (MRI) rooms and toll-free roads.

Additionally, FRP-reinforced concrete requires much less maintenance than steel-reinforced concrete, says El-Salakawy.

“Maintenance for things like concrete deterioration, joint leaks and accidents is minor compared to steel corrosion, especially in harsh climates, like Canada’s,” he said. he declares.

On the other hand, FRP has negative mechanical properties, such as brittle fracture (sudden failure without warning) and relatively lower stiffness than steel.

“This can result in more flexible, non-ductile structures,” El-Salakawy said. “Ducility is needed in buildings to provide enough warning of potential failure so that tenants or building owners can take action – by repairing or evacuating – before the building fails.”

El-Salakawy says his research on FRP and GFRP-RC structures is “pioneering” in seismic design that requires the ductility of reinforcement.

He has undertaken advanced research on a range of large-scale structural components, including beam-to-column joints, slab-to-column connections and beam-to-slab-column connections, and column-to-foot connections (to simulate buildings of high rise and bridges in seismic zones).

El-Salakawy says the importance of his research to engineers and the construction industry is that it opens up the application of FRP reinforcement to many different types of reinforced concrete structures.

He hopes this will allow construction of structures that are completely corrosion-free anywhere, including seismic zones.

“But as it stands, even though the use of FRP reinforcement has increased, its applications are limited to a few structural elements, such as bridge deck slabs, bridge barriers and beams/girders. simple bridges,” El-Salakawy said.

Upcoming changes in design codes around the world (particularly in Canada and the United States) will incorporate the results of FRP strengthening research by El-Salakawy and other researchers and will cover most structures.

“The main focus of these new codes – and my work – is on the use of GFRP reinforcement, as it is much cheaper and has greater deformation capability. [how much it will lengthen under tension stress until it fails] than other types of FRP reinforcement, which makes it attractive to designers and infrastructure owners,” said El-Salakawy.

In the future FRP reinforced concrete is expected to be used on all kinds of concrete structures.

“At the moment, it is mainly used in the superstructure elements of bridges – bridge slabs and barriers – and is used very little in buildings,” he said.

El-Salakawy hopes FRP-reinforced concrete will eventually replace steel-reinforced concrete.

“It will take time, but we are moving in this direction, thanks to the very good research results we have obtained and the constant decline in the manufacturing costs of GFRP reinforcements,” he said.

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