Time-Variant Strength Capacity Model for GFRP Bars Embedded in Concrete
Publication: Journal of Engineering Mechanics
Volume 139, Issue 10
Abstract
Glass fiber-reinforced polymer (GFRP) concrete reinforcement exhibits high strength, is lightweight, can decrease time of construction, and is corrosion resistant. However, research has shown that chemical reactions deteriorate the GFRP reinforcing bars over time, resulting in a reduced tensile capacity. This paper develops a time-variant probabilistic model to predict the tensile capacity of GFRP bars embedded in concrete. The developed model is probabilistic to properly account for the relevant sources of uncertainties, including the statistical uncertainty in the estimation of the unknown model parameters (because of the finite sample size), the model error associated with the inexact model form (e.g., a linear expression is used when the actual and unknown relations are nonlinear), and missing variables (i.e., the model only includes a subset of the variables that influence the quantity of interest.) The proposed model is based on a general diffusion model, in which water or ions penetrate the GFRP bar matrix and degrade the glass fiber-resin interface. The model indicates that GFRP reinforcement bars with larger diameters exhibit lower rates of capacity loss. The proposed probabilistic model is used to assess the probability of not meeting the tensile strength requirement based on specifications over time and can be used to assess the safety and performance of GFRP reinforced systems. Sensitivity and importance analyses are carried out to explore the effect of the parameters and random variables on the probability estimates.
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Acknowledgments
This project was conducted in cooperation with TxDOT and the Federal Highway Administration (FHWA). The researchers gratefully acknowledge the assistance provided by TxDOT officials, in particular, Timothy E. Bradberry, David Hohmann, and German Claros.
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Information
Published In
Journal of Engineering Mechanics
Volume 139 • Issue 10 • October 2013
Pages: 1435 - 1445
Copyright
© 2013 American Society of Civil Engineers.
History
Received: Jan 12, 2011
Accepted: Dec 18, 2012
Published online: Dec 21, 2012
Published in print: Oct 1, 2013
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