Analytical Modeling of Concrete-Filled FRP Circular Tubes under Reversed Cyclic Bending

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Title: Analytical Modeling of Concrete-Filled FRP Circular Tubes under Reversed Cyclic Bending

Author(s): K. Helmi, A. Fam, and A. Mufti

Publication: Special Publication

Volume: 257

Issue:

Appears on pages(s): 71-90

Keywords: bending; concrete-filled tube; cyclic; fatigue life; FRP tubes; model

Date: 10/1/2008

Abstract:
This paper presents an analytical procedure for modeling concrete-filled fiber-reinforced polymer (FRP) tubes (CFFTs) subjected to reversed cyclic bending, including a method for predicting their fatigue life. The model employs procedures to account for creep and stiffness degradation of FRP and concrete. The predicted behavior compared reasonably well with experimental results of three large-scale CFFT specimens tested under reversed high-cycle fatigue. It was shown that excessive slip between the concrete core and FRP tube reduces fatigue life and, hence, the accuracy of prediction was better at lower moments as slip was less. A parametric study conducted showed that time-dependant properties of concrete and FRP affect the long-term deflection of CFFTs subjected to reversed cyclic bending. Increasing the loading frequency, for the same number of cycles, decreases the deterioration in the response in terms of excessive deflection. Finally, CFFT members with a larger diameter-to-thickness (D/t) ratio (that is, smaller FRP reinforcement ratio) suffer a slightly larger deterioration in their cyclic response than CFFTs with smaller D/t ratio.