| Concrete filled Fiber Reinforced Polymer (FRP) tubes (CFFTs) provide a non-corrosive alternative to conventional materials in many applications. Studies performed on CFFT in the past have mostly been focused on characterizing their short-term monotonic behavior, leaving areas in need of further investigation. In this thesis, a research program was conducted to address three of these areas namely, the effects of driving forces on CFFT piles, a splicing system for CFFTs, and the fatigue behavior of CFFTs under reversed cyclic bending.; To study the effects of the driving forces, four 367 mm diameter CFFT piles, one of which was with a splice, were driven into the ground and then extracted. The piles were cut into 6.0 m and 0.3 m long sections that were used for beam tests, tensile and compression coupon tests, tension-tension fatigue tests, and push-off bond tests. Test results were compared to those of control specimens, which were not subjected to driving forces. The study showed that driving forces had insignificant effect on the CFFTs or the GFRP tubes. The mechanical splice used in this study showed adequate behavior and a slightly higher moment capacity than that of the CFFT pile it self, and therefore is considered successful.; To study the fatigue behavior of CFFT beams three full-scale 4.0 m long specimens were tested under reversed cyclic bending. Eighty on GFRP coupons, cut from the tubes, were also tested. Several parameters were varied including the type of coupon, loading frequency, and the type of test whether tension-tension or tension-compression. It was shown that some stiffness degradation behavior occurs, and that CFFTs seem to have a relatively short fatigue life under bending moments of about 40% and higher of their ultimate static bending moment capacities. However, a fatigue life of one million cycles or more could be achieved if the maximum bending moments is limited to 25-30% of the ultimate static bending moment and lower. The coupon tests showed that fatigue life will vary significantly with varying coupon type, loading frequency and including a compression component. The results also showed that the empirical equation suggested by Epaarachchi and Clausen (2003) could be used to represent fatigue life of FRP coupons, which could then be used to predict the fatigue life of full-scale CFFT specimens.; An analytical study was also conducted to model the behavior of CFFT beams under reversed cyclic bending. The results of this analytical modeling were compared to experimental results of CFFTs tested under reversed cyclic bending, showing reasonable agreement. A parametric study conducted using this model showed that both the concrete and FRP time-dependant properties have a significant contribution to the behavior of CFFT members subjected to reversed cyclic bending. The study also showed that the FRP tube diameter-to-wall thickness ratio have insignificant effect on fatigue life of CFFT flexural members. |
