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Tensile and Nondestructive Testing of FRP Bars.


pdf icon Tensile and Nondestructive Testing of FRP Bars. (1290 K)
Castro, P. F.; Carino, N. J.

Journal of Composites for Construction, Vol. 2, No. 1, 17-27, February 1998.

Keywords:

building technology; fiber reinforced plastic; modulus of elasticity; nondestructive testing; reinforcing bars; reasonant frequency; statistical methods; tensile test; ultrasonic pulse velocity

Abstract:

An exploratory study was carried out to support the development of standard test methods for fiber reinforced plastic (FRP) bars for use as concrete reinforcement. The principal objectives were to develop a simple, economical, and effective system to permit tensile loading of the bars in a universal test machine; to evaluate the influence of the free-length-to-bar-diameter ratio on the measured tensile strength; and to explore the potential of measuring the elastic modulus using available nondestructive test methods. A successful system for applying tensile load was developed. The ends of a bar were embedded in steel tubes using a high-strength gypsum cement mortar. The bars were loaded by gripping the tubes in the conventional wedge friction grips of a tensile testing machine. No statistically significant influence of the free-length-to-diameter ratio was observed for ratios varying between 40 and 70. However, large within-test variability of tensile strength was observed. Dynamic modulus of elasticity was determined using two stress-wave propagation methods: ultrasonic pulse velocity and resonant frequency. The dynamic values compared favorably with static values obtained from tensile stress-strain curves. Recommendations are provided for additional studies to support the development of standard test methods.