Analysis of circular concrete members reinforced with composite glass-FRP spirals

In this investigation, full-scale reinforced-concrete (RC) circular-beams with glass fibre reinforcement polymer (GFRP) bars and spirals were modeled using nonlinear finite element (FE) program. All the specimens had 3000mm length. The RC-beams were modeled in a three-dimension space, taking into account the material nonlinearity and the elastic plastic behavior of the concrete, in addition to the elastic characteristics of the GFRP materials. The results of the numerical analysis were verified by comparing them against experimental results of six similar previously tested specimens, that had 500-mm diameter. The analysis included tracing the loaddeformation response of the RC circular-beams, load-strains behavior on the surface of the concrete as well as the strains in the GFRP bars. The outputs from the FE analysis showed that the program was able to foresee the experimental results with good precision. The, average, value for the experimental shear strength to the foreseen ones by the FE program, (Vexp/VModel) for the six beams, is "1.00 +/- 0.05 '' with 2.5% COV. After ward, a parametric study was performed to expand and evaluate more parameters such as size effect (200, 300, and 400 mm), span-to-depth (a/d) ratio from 1.5 to 3.5, and spirals' reinforcement ratio between 0.32 and 1.27%. The numerical investigation confirmed the prominent effect of these parameters on the shear strength and behavior of the GFRP-RC circular-beams.