Strain monitoring of RC members strengthened with smart NSM FRP bars

Fiber-reinforced polymer (FRP) bars can be used as internal reinforcement for new reinforced concrete (RC) structures and as near-surface mounted (NSM) reinforcement for the strengthening of RC structures. The NSM method is an emerging strengthening technique for RC structures, where FRP bars are embedded into grooves cut in the cover of RC members. In both cases, strain monitoring of the FRP bars is desirable either for the investigation of the structural behavior or for the long-term health monitoring of the structure. This paper presents a study in which fiber-optic sensors were embedded into glass FRP (GFRP) bars to produce smart GFRP bars for NSM applications. The manufacturing process of the smart FRP bars is illustrated and their performance in tensile, bond and beam flexural tests is examined to assess the effectiveness of these smart FRP bars for achieving the dual purpose of structural strengthening and strain monitoring. On the basis of the test results, the advantages and limitations of fiber-optic sensors compared to electrical strain gages in the strain monitoring of NSM FRP bars are discussed. The bond and beam test results also confirm the effectiveness of the NSM method for the strengthening of RC structures.

[1]  Libo Yuan,et al.  CTOD measurement for cracks in concrete by fiber optic sensors , 2004 .

[2]  L. Lorenzis,et al.  Near-surface mounted FRP reinforcement: An emerging technique for strengthening structures , 2007 .

[3]  Kin-tak Lau,et al.  Fibre-optic sensors and smart composites for concrete applications , 2003 .

[4]  Giovanni Pascale,et al.  Internal Strain Measurements in Concrete Elements by Fiber Optic Sensors , 2003 .

[5]  K. Chandrashekhara,et al.  Smart fiber-reinforced polymer rods featuring improved ductility and health monitoring capabilities , 2001 .

[6]  Farhad Ansari State-of-the-art in the applications of fiber-optic sensors to cementitious composites , 1997 .

[7]  Farhad Ansari,et al.  Embedded fiber optic crack sensor for reinforced concrete structures , 2000 .

[8]  Laura De Lorenzis,et al.  Anchorage Length of Near-Surface Mounted Fiber-Reinforced Polymer Rods for Concrete Strengthening-Analytical Modeling , 2004 .

[9]  Farhad Ansari,et al.  Fiber-optic laser speckle-intensity crack sensor for embedment in concrete , 2006 .

[10]  Brahim Benmokrane,et al.  USE OF FIBRE REINFORCED POLYMER REINFORCEMENT INTEGRATED WITH FIBRE OPTIC SENSORS FOR CONCRETE BRIDGE DECK SLAB CONSTRUCTION , 2000 .

[11]  Aftab A. Mufti FRPs and FOSs lead to innovation in Canadian civil engineering structures , 2001 .

[12]  Libo Yuan,et al.  Embedded white light interferometer fibre optic strain sensor for monitoring crack-tip opening in concrete beams , 1998 .

[13]  John P. Newhook,et al.  Strain and deformation monitoring in infrastructure using embedded smart FRP reinforcements , 2005 .

[14]  Brahim Benmokrane,et al.  Evaluation of fibre optic sensors for structural condition monitoring , 2002 .

[15]  Farhad Ansari,et al.  Embedded fiber optic sensor for characterization of interface strains in FRP composite , 2002 .

[16]  David G. Bellemore,et al.  Distributed fiber Bragg grating strain sensing in reinforced concrete structural components , 1997 .

[17]  Libo Yuan,et al.  Fiber optic 2-D sensor for measuring the strain inside the concrete specimen , 2001 .

[18]  R. C. Tennyson,et al.  Fibre optic sensors in civil engineering structures , 2000 .

[19]  Antonio Nanni,et al.  Bond between Near-Surface Mounted Fiber-Reinforced Polymer Rods and Concrete in Structural Strengthening , 2002 .

[20]  Wei Jin,et al.  Strain monitoring in composite-strengthened concrete structures using optical fibre sensors , 2001 .

[21]  Farhad Ansari,et al.  Crack tip opening displacement in micro-cracked concrete by an embedded optical fiber sensor , 2005 .

[22]  Kyriacos Kalli,et al.  Fiber Bragg Gratings: Fundamentals and Applications in Telecommunications and Sensing , 2000 .

[23]  Brahim Benmokrane,et al.  Fibre-reinforced polymer composite bars for the concrete deck slab of Wotton Bridge , 2003 .

[24]  Scott T. Smith,et al.  FRP: Strengthened RC Structures , 2001 .

[25]  Libo Yuan,et al.  Calibration of embedded fiber optic sensor in concrete under biaxial compression , 2004 .

[26]  R. Measures,et al.  Fiber-optic Bragg grating sensors for bridge monitoring , 1997 .

[27]  Bo Wang,et al.  Debonding Failures of RC Beams Strengthened with Near Surface Mounted CFRP Strips , 2006 .

[28]  A. Kalamkarov,et al.  Experimental and analytical studies of smart composite reinforcement , 1998 .

[29]  Libo Yuan,et al.  Strain monitoring in FRP laminates and concrete beams using FBG sensors , 2001 .

[30]  Alexander L. Kalamkarov,et al.  The use of Fabry Perot fiber optic sensors to monitor residual strains during pultrusion of FRP composites , 1999 .

[31]  Farhad Ansari,et al.  Circumferential strain measurement of high strength concrete in triaxial compression by fiber optic sensor , 2001 .

[32]  Libo Yuan,et al.  Long-gauge length embedded fiber optic ultrasonic sensor for large-scale concrete structures , 2004 .

[33]  Alexander L. Kalamkarov,et al.  Reliability assessment of pultruded FRP reinforcements with embedded fiber optic sensors , 2000 .

[34]  Yuan Libo,et al.  Fiber-optic crack-tip opening displacement sensor for concrete , 1997 .

[35]  Kenneth T. V. Grattan,et al.  Fiber optic sensor technology: an overview , 2000 .

[36]  Joan R. Casas,et al.  Fiber Optic Sensors for Bridge Monitoring , 2003 .