Shear-bond behavior of Fiber Reinforced Polymer (FRP) rods and sheets 4 th International Conference on Rehabilitation and Maintenance in Civil Engineering July, 2018 Aylie Han 1 , , Bundara S. Gan 2 , and Agung Budipriyanto 3 a Professor, Civil Engineering Department, Diponegoro University, Semarang, Indonesia b Professor, Department of Architecture, College of Engineering, Nihon University, Koriyama, Japan c Associate Professor, Department of Civil Infrastructure Engineering, Institut Teknologi Sepuluh Nopember, Surabaya, Indonesia 1
Han, Gan, Budipriyanto Background External reinforcing is a technology widely used to enhance the capacity of reinforced concrete members. Fiber Reinforced Plastics (FRP) offer a variety of products, including sheets and rods FRP sheet FRP rod Attached FRP 2 Surakarta, 11-12 July 2018
Han, Gan, Budipriyanto The Main Problem The bond between the FRP and concrete is of major importance to the performance of the composite material. Which of the two materials provides the best solution? How does their mode of failure differ from each other? The possible modes of failure are: 1. Failure of the FRP material 2. Concrete rupture 3. Bond failure in the ITZ; in the ITZ between the FRP and epoxy, or between the concrete and the epoxy resin The mode of failure is a function of concrete, FRP and epoxy resin material properties , the application techniques, the surface roughness and the structural element’s characteristics Surakarta, 11-12 July 2018 3
Han, Gan, Budipriyanto Research Objective When in bending, the bond response is distinguished into the shear and normal stress behavior External reinforcement Element in bending Concrete in flexural tension Concrete Bond in axial-compression Bond In tensile-shear External FRP Reinforcement Interface strain responses Shar and normal stresses Surakarta, 11-12 July 2018 4
Han, Gan, Budipriyanto Research Work The experimental test evaluated the bond response of FRP sheets and rods in pure shear Stirrups Ø8-100 Size in mm Reinforcement Unbonded FRP rod FRP rod Ø8 4D13 Stirrups Ø8-100 Bonded FRP rod Tensile pull- off bar D25 Steel bar D25 150 30 120 250 100 120 190 150 20 Unbonded FRP rod Bonded FRP rod Tensile pull-off bar D25 FRP rod test set-up 5 Surakarta, 11-12 July 2018
Han, Gan, Budipriyanto Stirrups Ø8-100 Reinforcement FRP sheet Unbonded FRP sheet 4D13 t = 0.5 Bonded FRP sheet Tensile pull- off bar D25 Steel bar D25 150 Steel bar 4D13 Styrofoam 120 150 50 150 150 50 200 Unbonded FRP sheets Bonded FRP sheet Styrofoam block Tensile pull-off bar D25 FRP sheet test set-up Surakarta, 11-12 July 2018 6
Han, Gan, Budipriyanto Results Failure Modes FRP sheets. Two failure modes were observed: 1. Concrete shear-tension 2. Debonding in the interface between the epoxy and the concrete, only detected in the “untreated concrete surfaces” Concrete shear failure Debonding 7 Surakarta, 11-12 July 2018
Han, Gan, Budipriyanto FRP rods. Two failure modes were observed: 1. Concrete shear-tension 2. Debonding in the interface between the epoxy and the rod, only detected in the rods with an embedment less than the ACI 440-08 required depth concrete Epoxy FRP rod Ø8 10 12 Concrete shear failure concrete Epoxy FRP rod Ø8 6 12 Debonding 8 Surakarta, 11-12 July 2018
Han, Gan, Budipriyanto Evaluation of Concrete Fracture Plane Unbonded length FRP Bonded length ITZ ½P α Vertical fracture angle Fracture envelope P (a) Cross section Fracture envelope Unbonded area P ½P θ Horizontal fracture angle (b) Plan view Fracture Angle Vertical α Horizontal θ Sheet 5 0 2 0 24 0 60 0 Rod 9 Surakarta, 11-12 July 2018
Han, Gan, Budipriyanto Evaluation of Concrete Fracture Plane Concrete shear failure, plan view Fracture Angle Vertical α Horizontal θ 5 0 2 0 Sheet 24 0 60 0 Rod 10 Surakarta, 11-12 July 2018
Han, Gan, Budipriyanto In Retrospect 18.0 4.00 18.00 16.8 debonding concrete shear failure Normalized concrete stress to ACI 16.00 15.0 Stresses in the ITZ (MPa) 14.00 3.00 12.0 12.00 10.00 9.0 2.00 8.00 5.3 6.0 6.00 4.8 1.00 3.3 4.00 2.6 3.0 2.00 0.0 0.00 0.00 Sheet Rod FRP Sheet FRP Rod ACI debonding debonding Ultimate load (kN) Concrete failure Debonding Sheet 40.0 33.0 Rod 26.5 21.5 11 Surakarta, 11-12 July 2018
Han, Gan, Budipriyanto Conclusions • The FRP sheets require additional treatment, beyond the advise of the FRP producer • The quality of the FRP sheets bond is very dependent on the application technique • The FRP rods need to be embedded in accordance to the ACI guidelines and half embedded rods should be avoided • In practice, the rods are more easily applicable , since they require less preparation area, and reduce the use of resin • The application of sheets , due to their large area, produces dust and noise pollution • The ACI code on bond shear overestimates the ultimate stress for rods, but underestimates the values for sheets 12 Surakarta, 11-12 July 2018
Han, Gan, Budipriyanto With special thanks to: Research Team: Ir. Hioe Hartono PT. SIKA Indonesia Prof. Buntara S. Gan Nihon University, Koriyama-Japan Prof. Hsuan-Teh Hu National Cheng Kung University, Tainan-Taiwan Agung Budipriyanto, Ph.D ITS, Surabaya-Indonesia Dr. Tech Sholihin As’ad UNS, Surakarta-Indonesia Prof. Dr. Tudjono Diponegoro University, Semarang-Indonesia Christhy Amalia Sapulete, ST. Master student Bugi Mahendra Bachelor student Wibowo Technician Sutio Technician 13 Surakarta, 11-12 July 2018
Han, Gan, Budipriyanto 14 Surakarta, 11-12 July 2018
Han, Gan, Budipriyanto 15 Surakarta, 11-12 July 2018
Han, Gan, Budipriyanto 16 Surakarta, 11-12 July 2018
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