A study on strain sensing and structural properties of RCC beam without stirrups using carbon fiber based concrete

Abstract

In present study, effect of micro carbon fibers on strain sensing property and structural behaviour of the reinforced concrete (RC) beams in absence of stirrups was experimentally investigated. A total of three RC beams of medium scale having dimensions of 125mm width, 350mm height and 1500 mm long were constructed without stirrups. All the three beams had different longitudinal reinforcement ratios (0.92%, 1.03% and 1.43%). All the beams had Carbon Fiber Based Concrete (CFBC) at top and bottom surface of the beam in mid span for a length of 350mm and depth of 78 mm. All the beams were tested to failure under four point bending test for evaluating strain sensing property and structural behaviour of Carbon fiber based concrete. Fractional Change in Resistance (FCR) was calculated for top and bottom surface of beam that had carbon fibers and co-relation between FCR of CFBC, concrete strain and strain in tensile reinforcement is plotted. It was observed that as load increases on the beam the FCR was increasing for bottom surface (tensile surface) and decreasing for top surface (compressive side). The trend of change in FCR for top and bottom surface is observed to be same as strain in tensile reinforcement and concrete changes respectively. It was also observed that this FCR can be used for strain and damage detection in beam as a NDT health monitoring approach. Further electrical properties and structural behaviour of all the beams is explained in detail.