Effects of stirrup spacing on shear performance of hybrid composite beams produced by pultruded GFRP profile infilled with reinforced concrete

Pultruded Glass Fiber-Reinforced Polymer (pultruded GFRP) composite produced by the pultrusion method has become popular in civil engineering applications due to its lightness, corrosion resistance and high strength. However, the use of the pultruded profile combining with reinforced concrete is still limited due to a lack of knowledge. Therefore, the behavior of the pultruded GFRP profile infilled with reinforced concrete beams (hybrid beams) is investigated. This study focused on the effects of stirrup spacing for the hybrid beams. Pursuant to this goal, a total of eight different beams were tested under fourpoint loading. One reference beam without the pultruded profile and seven hybrid beams having different stirrup spacings were considered. Moreover, the hybrid beams with and without stirrups were wrapped by unidirectional GFRP composite to investigate the effects of stirrup spacing on shear capacity of the beams strengthened by GFRP composite. The experimental findings revealed that tightening stirrups increased the load and energy dissipation capacities of the hybrid beams; however, it could not prevent brittle failure. On the other hand, wrapping hybrid beams with GFRP composite increased the load and energy dissipation capacities and also prevented brittle failure regardless of the presence of the stirrups. Therefore, it is strongly recommended that the unidirectional pultruded profiles should be strengthened with 90 degrees GFRP wrapping to have ductile behavior.

Automated summary

This study investigates the behavior of pultruded glass fiber-reinforced polymer (pultruded GFRP) composite in reinforced concrete beams and explores the effects of stirrup spacing. The findings indicate that tightening stirrups increases load and energy dissipation capacities, but does not prevent brittle failure. Wrapping the beams with GFRP composite enhances load and energy dissipation capacities and prevents brittle failure, regardless of the presence of stirrups.