Dagmar Svecova

Flexural Strength of Posttensioned Timber Beams

AbstractAn experimental program was conducted at the University of Manitoba to test salvaged timber stringers posttensioned with external carbon fiber–reinforced polymer (CFRP) bars or steel guy cables. A total of 22 creosote-treated Douglas-fir beams with dimensions of 130×330×4,500  mm were tested in three-point bending. Six beams out of the 22 were control beams without any reinforcement. The remaining 16 beams were posttensioned using different reinforcement configurations. Four beams were posttensioned with draped CFRP tendons (Group CD), four beams were posttensioned with straight CFRP tendons (Group C), four beams were posttensioned with draped steel cable (Group SD), and four beams were posttensioned with straight steel cable (Group S). The experimental results found that the strength and the stiffness for Group CD were increased on average by 70% and 10%, respectively, while the strength for Group C was increased on average by 56% and showed no significant increase in stiffness. In contrast, the ...

Shear Behavior of CFRP Prestressed Concrete T-Beams

AbstractThis paper contributes to the scarce research available regarding the shear behavior of carbon fiber–reinforced polymer (CFRP) prestressed concrete beams. The beams were subjected to four-point bending and tested with different shear span to depth (a/d) ratios of 1.5, 2.5, and 3.5, with and without transverse reinforcement. For each group of four beams, two were reinforced with minimum required glass fiber–reinforced polymer (GFRP) stirrups according to the Canadian highway bridge design code. The results showed that the flexural rigidity and the shear capacity of the beams increase significantly as the a/d ratio is reduced to 1.5 from 2.5. The data also showed that the minimum required GFRP stirrups are ineffective in beams with a/d=1.5 that are governed by arch action. The experimental results are compared to theoretical estimates from the shear formulas available in design codes and literature.