Fibre-reinforced polymer strengthening and fibre Bragg grating–based monitoring of reinforced concrete cantilever slabs with insufficient anchorage length of steel bars

Abstract

Reinforced concrete cantilever slabs are among structures that are most likely to develop structural integrity problems, as they are statically determinate and often exposed to the outdoor environment. This article presents an experimental study on the strengthening of reinforced concrete cantilever slabs where the anchorage of the top steel reinforcing bars into the adjacent wall was insufficient. The experimental study involved the use of a fibre-reinforced polymer strengthening system and fibre Bragg grating sensors for strain monitoring. The fibre-reinforced polymer strengthening system consisted of glass fibre–reinforced polymer sheets and glass fibre–reinforced polymer spike anchors which connected the glass fibre–reinforced polymer sheets to the adjacent concrete wall. The test results showed that the fibre-reinforced polymer strengthening system was effective in improving the load-carrying capacity of reinforced concrete cantilever slabs and the fibre Bragg grating sensors worked efficiently and reliably for strain monitoring. The debonding in glass fibre–reinforced polymer sheet/glass fibre–reinforced polymer anchor-to-concrete bonded joints was found to be a progressive process associated with an increasing load. The fibre-reinforced polymer strengthening system examined in this study is thus a potential ductile solution for deficient cantilever slabs.

An Experimental Investigation on Flexural Behavior of Reinforced Concrete Beams Strengthened by an Intelligent CFRP Plate with Built-In Optical Fiber Bragg Grating Sensors

“…Zhang and Yu present an experimental study on the FRP strengthening of RC cantilever slabs with insufficient anchorage of steel reinforcing bars and the associated strain monitoring using FBG sensors. The experimental program was designed to support a real FRP strengthening project [40]. The above researches have generally verified the excellent performance of FBG sensors in the strain monitoring of FRP composites.…”

“…More recently, the use of a structural health monitoring systems (SHMS) for evaluating the durability, serviceability, and safety of the structures reinforced through composite materials in real time shows great potential by incorporating fiber optical sensors (FOSs) in composite materials during its forming process (e.g., wet lay-up process or pultrusion process); they offer a variety of advantages, for example, durability in harsh environment, immunity to electromagnetic interference, small size, and higher material compatibility. The FBG sensing technology with great potential for applications in the FOSs embedded into the composite materials is used for strain and temperature sensing at the local control section of strengthened members owing to its high sensitivity, repeatability, accuracy, and quasi-distributed and single-ended measurement [29][30][31][32][33][34][35][36][37][38][39][40]. Lu and Xie exploited the smart hand wet laid-up CFRP sheets embedded with the FBG sensor to strengthen the RC beams, and the load effect of the strengthening RC beam has been assessed by the smart CFRP sheet measurements [30,31].…”