Behavior of concrete filled frp tubes under fully reversed cyclic bending

الملخص EN

Concrete filled Fiber Reinforced Polymer (FRP) tubes (CFFT) are currently being used as piles in corrosive marine applications and as columns in bridge piers, and could be used in overhead sign structures.

CFFTs provide a non-corrosive alternative to conventional materials.

Studies conducted on CFFTs in the past decade have been mostly focused on the short-term monotonic behavior of this system in bending and under axial loads, with hardly any information available on their fatigue behavior.

In this paper the details of a research program that was conducted to address this issue and its results are presented.

The program included the testing of two full-scale specimens under reversed cyclic bending.

The program also included the testing of several coupons, cut from the tubes in tension–tension fatigue.

The full-scale tests showed that CFFTs seem to have a relatively short fatigue life under bending moments of 40% and higher of their ultimate static bending moment capacities, and that strains and deflections tend to increase gradually during cyclic bending indicating a stiffness degradation behavior.

The coupon tests showed that rapid stiffness degradation occurs initially then reduces due to the cracking of the matrix in the hoop layers, and that a fatigue life of millions of cycles could be reached for stresses less that 30% of the ultimate tensile stress.