Title: Behavior of Reinforced Concrete Columns with Hybrid Reinforcement (Steel/Glass Fiber-Reinforced Polymer) under Reversed Cyclic Load
Author(s): Girish Narayan Prajapati, Ahmed Sabry Farghaly, and Brahim Benmokrane
Publication: Structural Journal
Appears on pages(s): 141-155
Keywords: design codes; displacement ductility; glass fiber-reinforced polymer (GFRP) spirals and crossties; hybrid reinforcement; hysteretic response; reinforced concrete columns; reversed cyclic load.
This paper presents the results of laboratory testing of four full-scale
concrete columns reinforced with hybrid reinforcement consisting of longitudinal steel bars and transverse glass fiber-reinforced polymer (GFRP) spirals and crossties. The columns had an overall height of 1850 mm (72.8 in.) and cross section of 400 x 400 mm (15.8 x 15.8 in.). The reinforcement parameters were the transverse reinforcement ratio (1.27, 1.06, and 0.85%) and longitudinal steel bar size (No. 5 and 6). The columns were subjected to constant axial load and reversed lateral cyclic loading with increased amplitude until failure. Test results show that column failure depended on the amount of reinforcement. All the columns achieved drift values consistent with the requirements of the relevant design codes. The strain profile of the GFRP spirals and crossties during the test show their effectiveness in providing confinement after the steel yielded. Spacing of the transverse reinforcement affected column drift capacity. The test results show strength values consistent with North American design codes. The measured lateral effective stiffness was close to the required values in ACI 318 and ASCE/SEI 41. Moreover, the test results provided reliable evidence regarding the best approach for optimally combining the two structural materials (steel and GFRP).