Moment Connection of Concrete-Filled Fiber Reinforced Polymer Tubes by Direct Embedment into Footings

TLDR: A moment connection of concrete-filled fiber reinforced polymer (FRP) tubes (CFFTs) to concrete footing is explored in this article, where CFFTs are directly embedded into the footings to develop their full moment capacity, in lieu of using mechanical connections, dowel reinforcing bars, or posttensioning methods.

Abstract: A moment connection of concrete-filled fibre reinforced polymer (FRP) tubes (CFFTs) to concrete footing is explored. The CFFTs are directly embedded into the footings to develop their full moment capacity, in lieu of using mechanical connections, dowel reinforcing bars, or posttensioning methods. CFFT specimens of 219 mm diameter (D) were embedded into footings, at various depths, ranging from 0.3D to 1.5D. The CFFT cantilevered specimens were then laterally loaded to failure. The objective was to establish the critical embedment length, which was found to be 0.73D. Shorter embedment lengths resulted in a bond failure associated with excessive slip, where the full flexural strength of CFFTs was not reached. Specimens with the critical or longer embedment lengths have achieved flexural tension failure of the CFFT, just outside the footing. Ancillary push-through tests were also carried out using CFFT stubs embedded into concrete footings, throughout the full thickness of the footing, and tested under conce...