Shear-bond behavior of Fiber Reinforced Polymer (FRP) rods and - - PowerPoint PPT Presentation

Shear-bond behavior of Fiber Reinforced Polymer (FRP) rods and sheets

4th International Conference on Rehabilitation and Maintenance in Civil Engineering July, 2018

Aylie Han1, , Bundara S. Gan2, and Agung Budipriyanto3

aProfessor, Civil Engineering Department, Diponegoro University, Semarang, Indonesia bProfessor, Department of Architecture, College of Engineering, Nihon University, Koriyama, Japan cAssociate Professor, Department of Civil Infrastructure Engineering, Institut Teknologi Sepuluh Nopember, Surabaya,

Indonesia 1

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

Background

Han, Gan, Budipriyanto

2

Surakarta, 11-12 July 2018

FRP sheet Attached FRP FRP rod

Han, Gan, Budipriyanto

Surakarta, 11-12 July 2018

3

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: 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

• 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

Han, Gan, Budipriyanto

Surakarta, 11-12 July 2018

4

Research Objective

When in bending, the bond response is distinguished into the shear and normal stress behavior

External reinforcement

Element in bending

Bond In tensile-shear FRP Concrete in flexural tension Bond in axial-compression

Shar and normal stresses Interface strain responses

Concrete External Reinforcement

Han, Gan, Budipriyanto

Surakarta, 11-12 July 2018

5

Research Work

The experimental test evaluated the bond response of FRP sheets and rods in pure shear

FRP rod test set-up

Stirrups Ø8-100 Unbonded FRP rod Bonded FRP rod Tensile pull-

• ff bar D25

150

Reinforcement 4D13

120 250 20 30 100 120 190

Size in mm FRP rod Ø8 Stirrups Ø8-100 Steel bar D25

150

Unbonded FRP rod Bonded FRP rod Tensile pull-off bar D25

Han, Gan, Budipriyanto

Surakarta, 11-12 July 2018

6

FRP sheet test set-up

Unbonded FRP sheets Bonded FRP sheet Tensile pull-off bar D25 Styrofoam block 150 Stirrups Ø8-100 Unbonded FRP sheet Bonded FRP sheet Tensile pull-

• ff bar D25

150 Reinforcement 4D13 120 200 50 50 150 FRP sheet t = 0.5 Steel bar D25 Steel bar 4D13 150 Styrofoam

Han, Gan, Budipriyanto

Surakarta, 11-12 July 2018

7

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

Han, Gan, Budipriyanto

Surakarta, 11-12 July 2018

8

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 shear failure

Epoxy FRP rod Ø8 12 10 concrete

Debonding

Epoxy FRP rod Ø8 6 12 concrete

Han, Gan, Budipriyanto

Surakarta, 11-12 July 2018

9

Evaluation of Concrete Fracture Plane

Bonded length

½P

Unbonded length Fracture envelope Vertical fracture angle FRP ITZ

P

(a) Cross section

α θ ½P P

Fracture envelope Horizontal fracture angle Unbonded area (b) Plan view Fracture Angle Vertical α Horizontal θ Sheet 50 20 Rod 240 600

Han, Gan, Budipriyanto

Surakarta, 11-12 July 2018

10

Evaluation of Concrete Fracture Plane

Fracture Angle Vertical α Horizontal θ Sheet 50 20 Rod 240 600 Concrete shear failure, plan view

Han, Gan, Budipriyanto

Surakarta, 11-12 July 2018

11

Ultimate load (kN) Concrete failure Debonding Sheet 40.0 33.0 Rod 26.5 21.5

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00

0.00 1.00 2.00 3.00 4.00 Normalized concrete stress to ACI 3.3 16.8 5.3 2.6 4.8 0.0 3.0 6.0 9.0 12.0 15.0 18.0

Sheet debonding Rod debonding FRP Sheet FRP Rod ACI

Stresses in the ITZ (MPa) debonding concrete shear failure

In Retrospect

Han, Gan, Budipriyanto

Surakarta, 11-12 July 2018

12

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

Han, Gan, Budipriyanto

Surakarta, 11-12 July 2018

13

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

Han, Gan, Budipriyanto

Surakarta, 11-12 July 2018

14

Han, Gan, Budipriyanto

Surakarta, 11-12 July 2018

15

Han, Gan, Budipriyanto

Surakarta, 11-12 July 2018

16