Modified Shear Design Model for Steel and FRP-Reinforced Concrete Beams
Ahmad N. Tarawneh, Eman F. Saleh, Abdullah M Alghossoon, Ghassan S. Almasabha, Omar S. Alajarmeh, Allan Manalo, Brahim Benmokrane
Appears on pages(s):
ACI 440; axial stiffness; code evaluation; concrete; fiber-reinforced polymer (FRP) reinforced-concrete (RC) beams; fiber-reinforced polymer (FRP) reinforcement; reliability analysis; steel reinforcement; steel reinforced-concrete beams; shear strength
This study proposes a unified shear design provision for slender steel- and FRP-reinforced concrete (RC) members. The proposed model is a modification of the ACI 318-19 model to include the axial stiffness of the longitudinal reinforcement by introducing a new modification term, nc, representing the elastic modular ratio of the longitudinal reinforcement to the concrete. The new relation is Vc=(0.4 [nc ρfl]1/3 λs √f’c+Nu/[6Ag]) bw d. The unified shear model was assessed with five experimental datasets: FRP-RC beams without shear reinforcement (288 beams), steel-RC beams without shear reinforcement (759 beams), FRP-RC beams with shear reinforcement (56 beams), steel-RC beams with shear reinforcement (157 beams), and steel-RC beams with axial force (prestressed) but without shear reinforcement (209 beams). The unified shear model provided better performance than the ACI 318-19 and ACI 440.11-22 provisions in terms of mean, coefficient of variation, standard deviation, and absolute average error. The unified model also showed improved performance over a wider range of material properties. In addition, reliability analysis using Monte Carlo simulation indicated that the unified shear model provides a consistent satisfactory safety level with a reliability index between 3.5 and 4.0 for both steel and FRP-RC members. The reliability index provided by the unified model is similar to the reliability index provided by the ACI 318-19 shear provision. In contrast, the ACI 440.11-22 results in highly conservative estimates with a reliability index between 4.5 and 5.0.