Experimental study of concrete columns with localized failure

To study the stress-strain behavior of axially loaded fiber-reinforced polymer (FRP)-confined concrete columns in the event of a localized failure, 32 circular concrete cylinders were tested with heavy instrumentations. The test specimens had a diameter of 150 mm and a length varying from 300 to 700 mm. Another test variable was confinement, of which 6 different levels were used. To identify the localized failure zone and its effect, a large number of electrical strain gauges and digital image correlation (DIC) techniques were used to capture strain variation along the full height of the cylinders. Measured strain fields and local load-deformation curves were used to identify the length of the zone and the compression fracture energy required for stress-strain modeling of columns with failure localization. The test results show that both the length of the failure zone and the compression fracture energy increase when confinement increases. The experimental results from this work provide adequate data and information for development of a stress-strain model of FRP-confined concrete columns involving failure localization.