This paper presents an assessment of the seismic performance of concrete columns internally reinforced with glass-fiber-reinforced polymers (GFRP) bars. Eight full-scale column prototypes with 1,650-mm shear span and 350-mm square cross-section were constructed and tested under combined lateral cyclic quasi-static and constant axial loading. The test specimens represent the lower portion of first-story columns between the footing and the contra-flexure point. The test parameters included longitudinal reinforcement type and ratio, level of axial load, and stirrup spacing. Test results showed that the drift capacity of GFRP-reinforced concrete (RC) rectangular columns at failure ranged between 8.5 and 12.5%, which exceeds the limitations of North American building codes. This indicates that the deformability of GFRP-RC column prototypes successfully replaced the ductility in steel–RC columns in dissipating the seismic energy in the presence of constant axial load. Furthermore, there was insignifican...

This paper presents test results of seven large-scale circular concrete columns reinforced with either steel or glass fiber-reinforced polymer (GFRP) reinforcement. The columns measured 355 mm in diameter and 1,750 mm in length and were tested to failure under concentric, eccentric, or four-point bending configuration. Test parameters included the reinforcement type (GFRP and steel), the GFRP spiral pitch (50 and 85 mm), and varying ratios of eccentricity-to-column diameter (e/D = 0, 0.085, 0.17, and 0.34). The obtained axial capacity of the GFRP-reinforced concrete (RC) column was approximately 17% less than that of the steel-RC counterpart. However, for e/D = 0.085, the GFRP-RC column with a lesser spiral pitch exhibited approximately 10% more axial capacity than the column with a larger pitch. As the e/D ratio increases from 0 to 0.34 the axial capacity reduced by 32%, 39%, and 70% from the axial capacity of the concentric column. A “knee”-shaped interaction diagram for circular GFRP-RC columns was developed and compared with the predictions of available codes and guidelines for GFRP-RC structures.

The demand for sustainable concrete structures with longer service life and lower maintenance cost has been driving the use of glass fiber-reinforced polymer (GFRP) reinforcement in new concrete structures. The behavior of GFRP bars under seismic loading in reinforced concrete (RC) frame structures has not been widely investigated. Furthermore, the ability of FRP-RC frame structures to dissipate energy in seismic events is still questionable due to the elastic-linear behavior of the FRP reinforcement. Very few studies have been conducted on the seismic behavior of GFRP-RC exterior beam-column joints, and none studied the shear capacity of joints. Therefore, this study attempts to partially fill this gap by investigating the shear capacity of beam-column joints reinforced with GFRP bars and stirrups. Six full-scale exterior beam-column joint prototypes (T-shaped) were constructed and tested under simulated seismic load conditions. Test parameters in this study included the concrete strength and the...

This paper presents the test results of five full-scale reinforced concrete (RC) interior slab–column connections. Each specimen consisted of a 2,800-mm square slab with a thickness of 200 and 300-mm square central column stubs. Four slabs were reinforced with glass fiber–reinforced polymer (GFRP) bars and one reference slab was reinforced with steel bars. The connections were subjected to eccentric load with a moment-to-shear ratio equal to 0.15 m. The test parameters included the type and ratio of the reinforcement and concrete compressive strength. Test results revealed that increasing the GFRP reinforcement ratio or the concrete strength increased the connection capacity and decreased the deformation of the tested slabs. Moreover, the GFRP-RC connection that has similar reinforcement rigidity to the steel-RC one showed comparable capacity and deflection at failure. Test results were compared with different available models and design provisions including the Canadian standard, the American gui...

Six full-scale specimens were constructed and tested under reversal cyclic loading to study the seismic behavior of exterior glass-fiber-reinforced-polymer (GFRP) reinforced concrete (RC) beam–column joints with lateral beams. Five specimens were completely reinforced with GFRP bars and stirrups and one was reinforced with conventional steel as a control specimen. The main test variables were reinforcing materials (GFRP and steel), presence of lateral beams, different joint shear stresses, and end anchorage of beam longitudinal bars (bent and headed-end bars). The specimens were subjected to increasing seismic drifts up to failure. Test results showed that GFRP-RC exterior beam–column joints confined with lateral beams can resist joint shear stress equal to 1.1 times the square root of the concrete compressive strength up to 6% drift ratio. In some cases, the specimens showed nonlinear behavior and nonbrittle failure, contrary to what it is expected from FRP-RC structures. Moreover, the anchorage ...

Six full-scale reinforced-concrete (RC) interior slab-column connections of glass fiber–reinforced polymer (GFRP) were constructed and tested to failure. The specimen consisted of a square slab with a 2,800-mm side length and a 200-mm thickness in addition to a 300-mm-square column stub extended for 1,000 mm above and below the slab. The test specimens were subjected to vertical shear forces and unbalanced moments. The test variables included the moment-to-shear ratio, GFRP double-headed shear studs ratio, and the type of GFRP bar surface texture (ribbed or sand-coated). The test results revealed that increasing the moment-to-shear ratio reduced the vertical shear capacity and increased the deflections and the strains at failure. Moreover, the presence of the GFRP shear studs enhanced the slab capacity but was not able to change the punching shear mode of failure. Furthermore, the used two types of GFRP bars showed comparable behavior. The results were compared with the predictions of the availabl...