Large beam-column tests on concrete-filled composite tubes
columns (supports); fibers; prestressed concrete; slenderness ratio; Construction & Building Technology; Engineering, Civil; Materials; Science, Multidisciplinary
The concept of concrete-filled composite tubes was developed to address the corrosion problems associated with reinforced and prestressed concrete piles. Beam-column tests on a total of sixteen 2.75 m long specimens demonstrated the feasibility of off-the-shelf fiber-reinforced polymer (FRP) products. Two types of tubes were used: spin-cast (I) and filament-wound (II). Based on their respective brittle-brittle reinforcement ratios, Type I and II specimens were considered as over-reinforced and under-reinforced concrete sections, respectively. The tests showed that over-reinforced specimens performed superior as beam-columns. They deflected to a lesser extent, and failed at much higher axial and lateral loads, while their failure was still gradual and ductile. They were also more efficient, as a smaller portion of their sectional capacity was consumed by secondary moment effects. Bond failure was not an issue in beam-columns. Therefore, off-the-shelf tubes can be used as long as end conditions and connections are properly designed. It is necessary, however, to provide a shear transfer mechanism for beams. In comparison with prestressed concrete columns, the 348 mm diameter Type I specimens were found comparable to 584 mm diameter circular sections prestressed with 20 strands of Grade 1862 MPa, whereas the 369 mm Type II specimens were found comparable to 460 mm square sections prestressed with eight strands.
Aci Structural Journal
Mirmiran, A. , Shahawy, A. , El Khoury, C., Naguib, W. (2000). Large beam-column tests on concrete-filled composite tubes. Aci Structural Journal, 97(2).