The effect of tube damage on flexural strength of ±55° angle-ply concrete-filled FRP tubes

Abstract

The ±55° angle-ply filament-wound glass fibre reinforced polymer (GFRP) tubes are quite common commercially and have been used in concrete-filled FRP tubes (CFFTs). However, it is not clear how would a damage in the form of a cut in the tube affects the CFFT strength. This paper presents an experimental investigation to address the effects of controlled longitudinal and circumferential linear cuts, up to 22% of the perimeter (πD) in length, through the full wall thickness, on their flexural strength. The cuts were induced at mid-span on the tension and compression sides of 1420 mm long CFFTs with a 142 mm outer diameter and 4.1 mm wall thickness. Twelve specimens, including control ones without cuts to establish the full strength Mo, were tested in four-point bending. At a 10% πD cut, flexural strength dropped to 0.69Mo and 0.73Mo, respectively, for circumferential and longitudinal tension side cuts. Results were compared to another study on CFFTs with near cross-ply tubes, which were more vulnerable than angle-ply CFFTs. Compression side longitudinal and circumferential cuts in both types of tubes were less critical, with about 12% loss in strength. A design case study is also presented.