Torsional Behaviour of Precast Concrete Planks Reinforced with Glass Fibre Reinforced Polymer Bars

Bielefeld, Kristin (2021) Torsional Behaviour of Precast Concrete Planks Reinforced with Glass Fibre Reinforced Polymer Bars. [USQ Project]

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BIELEFELD Kristin dissertation_redacted.pdf

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There is increasing need to find a replacement reinforcing for concrete structures, especially in harsh marine environments. The standard is currently to use steel reinforcing which rusts when in contact with water, known as corrosion. The Queensland Department of Transport and Main Roads (TMR) came to the staff at the University of Southern Queensland (USQ) with an offer to fund a project to investigate replacing the standard steel reinforcing with glass fibre reinforced polymer (GFRP) bars in their floating walkways.

Using GFRP bars as reinforcing will extend the life of any concrete structure is used in. As well as being corrosion resistant, it is also a third of the weight of steel and much stronger at 60GPa tensile strength versus steels 500MPa. Due to there being no previous research on rectangular planks under torsional load, reinforced with GFRP bars, this is what will be tested in this project.

The planks tested were large scale at 2.4m x 1.5m x 0.125m. Two planks were tested with different reinforcement layers to gather an understanding of how the layout affected the torsional behaviour of the planks. A testing setup was developed at USQ to test the planks under torsional load.

Each plank was clamped into the testing setup and had a ram applied to one corner of the plank to load the planks. The load was recorded as well as the deflection and strain gauges recorded the microstrain of the reinforcing and concrete at strategic points on the planks.

The resulting data from the strain gauges and the deflection was graphically displayed to determine an understanding of the behaviour of the planks. Drawings were also done of the resulting cracks in the surface of the planks so they could be compared.

A theoretical calculation was performed of the concrete cracking torque and ultimate torque so that these could be compared to the experimental results. The experiment results were also compared to the load which the plank is required to hold including a 5 tonne impact load TMR had specified in their design criteria.

The results showed very similar results for the crack patterns of each plank as well as a similar rotation angle for each maximum load recorded. The cracking torque for each plank matched the theoretical cracking torque, while the theoretical ultimate torque well exceeded the recorded ultimate torque for both planks which is to be expected with the tensile strength of GFRP at approximately 1000 times that of steel. The results showed that while the one layer plank could withstand all of the load conditions including the impact loading, there will be less damage to the two layer plank for the same load as it is stiffer as a result of having two layers of reinforcing.

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Item Type: USQ Project
Item Status: Live Archive
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying (1 Jul 2013 - 31 Dec 2021)
Supervisors: Manalo, Allan
Qualification: Bachelor of Engineering (Honours) (Civil)
Date Deposited: 21 Dec 2022 03:43
Last Modified: 25 Jun 2023 23:52
Uncontrolled Keywords: marine, concrete, torsion, polymer, glass fibre, behaviour, corrosion, GFRP bars, reinforce

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