Research On The Mechanical Properties Of Axially Loaded GFRP Tubed Reinforced Concrete Columns

Concrete-filled FRP tubes can provide an excellent alternative for concrete effectivelysubjected to corrosive environmets,adapting to the development of modern structures towardbig-span,high rise and heavy-load.Wide concen has been focused on it, it aready become oneof the most popular item on new style composite structures.The results corresponding hasbeen drawn a lot,however,studies on FRP Tubed reinforced concrete columns have been verylimited(The FRP tubes are used to transversly confine concrete,not bearing the axialloads).Based on experimental and theoretical analysis,the mechanical properties of the GFRPtubed reinforced concrete columns under axially loaded are researched.The major concentsare summarized as follows:1.Experimental research on the GFRP Tubed short reinforced concrete columns underaxially loaded are carried out to investigate the mechanical properties of working feature, theeffect of GFRP tube confining,ductility of the specimens.The effects of concrete strength,loading condition,ratio of longitudinal reinforcement and ratio of stirrups are researched.According to the experiment results together with the existed strength equation of FRP tubesconfined concrete,the strength model of the GFRP tubed short reinforced concrete columnsand the ultimate beating capacity of the composite short columns are proposed.2.The existed stress-strain calculated model for FRP tubes confined concrete are anal-yzed and compared,based on which two different model are proposed.The model can be usedto analysis FRP tubes confined common concrete,FRP tubes confined high strength concrete,and columns with reinforcement and stirrups. Stress-strain curves calculated by the proposedmodel is shown to the compare well with the experimental results.Some parameters affectingthe mechanical properties are researched using the proposed model,including concretestrength, D/t ratio and the properties of FRP tubes.3.Based on the experimental and calculated results,the mechanical properties of theaxially loaded slender composite columns are researched.The main concerns focus on theslenderness ratio effect to the load bearing capacity and deformation of the specimens.Thestability capacity of the slender composite columns under axial load is analyzed by tangentmodulus theory.Comparison between the theoretical and experimental results show that thismodel can give a favorable prediction for the stability capacity of the slender compositecolumns.Based on the experimental and theoretical results,simple formulas for estimating theaxial stability capacity of the slender composite columns are proposed.