Effect of Prestressing Ratio on Concrete-Filled FRP Rectangular Tube Beams Tested in Flexure
Asmaa Abdeldaim Ahmed, Mohamed Hassan, and Radhouane Masmoudi
Appears on pages(s):
prestressed concrete, CFFT, beams, GFRP, confinement, concrete strength, flexural, bridge
This paper presents the results of an extensive test program that was aimed at investigating the flexural behavior of rectangular concrete-filled glass fiber-reinforced-polymer (GFRP) tube (CFFT) beams post-tensioned (PT) with unbonded steel tendons. The tests intend to simulate a number of design parameters, which are mainly governed by flexural loading. All beams were tested under four-point bending over a simply supported span of 3,000 mm [1229 in.]. Four full-size beams with an identical rectangular cross-sectional of 305 mm × 406 mm [12.0 in. × 16.0 in.] were constructed. The investigated test parameters were the number of tendons (2 or 3) and concrete strength (40 or 65 MPa) [5.80 or 9.43 ksi]. Besides, a proposed design equation as an extension to AASHTO (2012) equation based on a regression analysis of the test results herein to predicate the flexural capacity is established. The test results show that the cracking loads and post-cracking stiffness can be improved by increasing the number of strands. However, increasing the number of strands shows a slight effect on the ultimate capacity. The flexural capacities of PT CFFTs can be enhanced by increasing the concrete compressive strength without affecting their overall ductility. The proposed model successfully predicts the ultimate moment capacity of the tested beams and other results from the literature with an average of 1.08±0.16 and a COV of 14.5%. However, due to the limited test results in the present study and, in the literature, additional tests on the flexural behavior of PT rectangular CFFT beams are needed to further validate the accuracy of the model.