Reliability-based durability assessment of GFRP bars for reinforced concrete


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Virginia Tech


The American Concrete Institute (ACI) has developed guidelines for the design of fiber reinforced polymer (FRP) reinforced concrete structures. Current guidelines require the application of environmental and flexural strength reduction factors, which have minimal experimental validation. Our goal in this research is the development of a Monte Carlo simulation to assess the durability of glass fiber reinforced polymer (GFRP) reinforced concrete designed for flexure. The results of this simulation can be used to determine appropriate flexural strength reduction factors.

Prior to conducting the simulation, long-term GFRP tensile strength values needed to be ascertained. Existing FRP tensile strength models are limited to short-term predictions. This study successfully developed a power law based-FRP tensile strength retention model using currently available tensile strength data for GFRP exposed to variable temperatures and relative humidity. GFRP tensile strength retention results are projected at 0, 1, 3, 10, 30, and 60-year intervals. The Monte Carlo simulation technique is then used to assess the influence beam geometry, concrete strength, fractions of balanced reinforcement ratio, reinforcing bar tensile strength, and environmental reduction factors on the flexural capacity of GFRP reinforced concrete beams.

Reliability analysis was successfully used to determine an environmental reduction factor of 0.5 for concrete exposed to earth and weather. For simulations with higher GFRP bar tensile strength as well as larger beam geometry and fractions of the balanced reinforcement ratio, larger moment capacities were produced. A strength reduction factor of approximately 0.8 is calculated for all fractions of balanced reinforcement ratio. The inclusion of more long-term moisture data for GFRP is necessary to develop a more cohesive tensile strength retention model. It is also recommended that longer life cycles of the GFRP reinforced concrete beams be simulated.

This research was conducted thanks to support from the National Science Foundation Division of Graduate Education's Interdisciplinary Graduate Education Research and Traineeship (Award # DGE-0114342) Note: The opinions expressed herein are the views of the authors and should not be interpreted as the views of the National Science Foundation.



Reliability, Concrete, Monte Carlo, Glass fiber reinforced polymer (GFRP)