THE PERFORMANCE OF CURVED NONNON--FERROUS REINFORCEMENT...
Transcript of THE PERFORMANCE OF CURVED NONNON--FERROUS REINFORCEMENT...
© 2006 The University of Sheffield
Western Bank, Sheffield S10 2TN, UK Miami, Florida, U.S.A.
CICE 2006
The 3rd International Conference on FRP Composites in Civil Engineering
THE PERFORMANCE OF CURVED NON-FERROUS REINFORCEMENT FOR CONCRETE STRUCTURES
THE PERFORMANCE OF CURVED THE PERFORMANCE OF CURVED NONNON--FERROUS REINFORCEMENT FERROUS REINFORCEMENT FOR CONCRETE STRUCTURESFOR CONCRETE STRUCTURESThanongsak ImjaiThanongsak ImjaiMaurizio GuadagniniMaurizio GuadagniniKypros PilakoutasKypros PilakoutasPeter WaldronPeter Waldron
Construction Innovation Research GroupDepartment of Civil and Structural Engineering
© 2006 The University of Sheffield
Western Bank, Sheffield S10 2TN, UK Miami, Florida, U.S.A.
CICE 2006
The 3rd International Conference on FRP Composites in Civil Engineering
•• Why bending reinforcement?Why bending reinforcement?
•• Design of bent reinforcementDesign of bent reinforcement
•• Performance of bent Performance of bent FRPFRP’’ss
•• Experimental programExperimental program
•• Experimental resultsExperimental results
•• ConclusionsConclusions
OutlineOutline
© 2006 The University of Sheffield
Western Bank, Sheffield S10 2TN, UK Miami, Florida, U.S.A.
CICE 2006
The 3rd International Conference on FRP Composites in Civil Engineering
Why bending reinforcement?Why bending reinforcement?Why bending reinforcement?
•• End anchoragesEnd anchorages
•• Element connectionElement connection
•• Shear reinforcementShear reinforcement
Types of curves (BS8666)Types of curves (BS8666)Types of curves (BS8666)
Minimum number?
Minimum number?
© 2006 The University of Sheffield
Western Bank, Sheffield S10 2TN, UK Miami, Florida, U.S.A.
CICE 2006
© 2006 The University of Sheffield
Western Bank, Sheffield S10 2TN, UK Miami, Florida, U.S.A.
CICE 2006
The 3rd International Conference on FRP Composites in Civil Engineering
Specification for bendingSpecification for bendingSpecification for bending
R ≥ 2d
Standardised shapes (BS8666)Standardised shapes (BS8666)
R
© 2006 The University of Sheffield
Western Bank, Sheffield S10 2TN, UK Miami, Florida, U.S.A.
CICE 2006
The 3rd International Conference on FRP Composites in Civil Engineering
Specification for bendingSpecification for bendingSpecification for bending
Typical steel
Typical GFRP
Plastic strain induced by bending
© 2006 The University of Sheffield
Western Bank, Sheffield S10 2TN, UK Miami, Florida, U.S.A.
CICE 2006
The 3rd International Conference on FRP Composites in Civil Engineering
Cold bending of FRP’sCold bending of Cold bending of FRPFRP’’ss
© 2006 The University of Sheffield
Western Bank, Sheffield S10 2TN, UK Miami, Florida, U.S.A.
CICE 2006
The 3rd International Conference on FRP Composites in Civil Engineering
The tensile strength of FRP bars can be largely reduced when subjected to a biaxial state of stress
Performance of bent FRP’sPerformance of bent FRP’s
Longitudinal directionTransverse
direction
© 2006 The University of Sheffield
Western Bank, Sheffield S10 2TN, UK Miami, Florida, U.S.A.
CICE 2006
The 3rd International Conference on FRP Composites in Civil Engineering
Performance of bent FRP’sPerformance of bent FRP’s
Premature failure at bent portionPremature failure at bent portion
© 2006 The University of Sheffield
Western Bank, Sheffield S10 2TN, UK Miami, Florida, U.S.A.
CICE 2006
The 3rd International Conference on FRP Composites in Civil Engineering
0.3bfb fu fu
b
rf f fd
α⎛ ⎞⎜ ⎟⎜ ⎟⎝ ⎠
= + ≤
rb is the radius of the bend in the bardb is the nominal diameter of the FRP barffu is the design strength of a straight portion …of the bar
Performance of bent FRP’sPerformance of bent Performance of bent FRPFRP’’ss
Design equation (JSCE, 1997)
© 2006 The University of Sheffield
Western Bank, Sheffield S10 2TN, UK Miami, Florida, U.S.A.
CICE 2006
The 3rd International Conference on FRP Composites in Civil Engineering
Use of thermoplastic FRP’sUse of thermoplastic Use of thermoplastic FRPFRP’’ss
•• Thermosetting Thermosetting FRPFRP’’ss can only be precan only be pre--bent at the bent at the factoryfactory
•• Thermoplastic Thermoplastic FRPFRP’’ss could offer a valid solution could offer a valid solution for onfor on--site bending of reinforcementsite bending of reinforcement
R/t ~ 13R/t ~ 1
© 2006 The University of Sheffield
Western Bank, Sheffield S10 2TN, UK Miami, Florida, U.S.A.
CICE 2006
The 3rd International Conference on FRP Composites in Civil Engineering
Use of thermoplastic FRP’sUse of thermoplastic Use of thermoplastic FRPFRP’’ss
1.48Density (g/cm3)
35Glass content (%v/v)
1.9Ultimate strain (%)
28Tensile modulus (GPa)
720Tensile strength (MPa)
Properties
GFRP thermoplastic strip (10x3mm)GFRP thermoplastic strip (10x3mm)
© 2006 The University of Sheffield
Western Bank, Sheffield S10 2TN, UK Miami, Florida, U.S.A.
CICE 2006
The 3rd International Conference on FRP Composites in Civil Engineering
Experimental programExperimental programExperimental program
Type 2 Type 3
Parameters Parameters (47 specimens)(47 specimens)-- R/t R/t (2 (2 –– 5)5)-- embedment length embedment length (60mm, 145mm)(60mm, 145mm)-- tail length tail length ((ttll/t/t = 5 = 5 –– 15)15)-- ffcucu (45MPa, 95MPa)(45MPa, 95MPa)-- surface treatment surface treatment (smooth, sand coated)(smooth, sand coated)
© 2006 The University of Sheffield
Western Bank, Sheffield S10 2TN, UK Miami, Florida, U.S.A.
CICE 2006
The 3rd International Conference on FRP Composites in Civil Engineering
Experimental resultsExperimental resultsExperimental results
0 4000 8000 12000 16000 200000%
14%
28%
42%
56%
0
100
200
300
400
strain (με)
stre
ss (M
Pa)
f / f fu
21
23
272529
Strain distribution in specimens Type 2
Failure behaviourFailure behaviour
© 2006 The University of Sheffield
Western Bank, Sheffield S10 2TN, UK Miami, Florida, U.S.A.
CICE 2006
The 3rd International Conference on FRP Composites in Civil Engineering
Experimental resultsExperimental resultsExperimental results
Strain Strain distributiondistribution in specimens Type 3in specimens Type 3strain (με)
0 4000 8000 12000 16000 200000%
14%
28%
42%
56%
0
100
200
300
400
f / f fu
stre
ss (M
Pa)
2123 2725
29
© 2006 The University of Sheffield
Western Bank, Sheffield S10 2TN, UK Miami, Florida, U.S.A.
CICE 2006
The 3rd International Conference on FRP Composites in Civil Engineering
Performance of bent FRP’sPerformance of bent FRP’s
r/t0 1 2 3 4 5 6
f / f fu
(%)
0
10
20
30
40
50
60
70
Type 2, SM, NType 2, SC, NType 2, SM, HType 2, SC, H
Bonded specimens (Type 2)
R/tr/t0 1 2 3 4 5 6
0
10
20
30
40
50
60
70
Type 2, SM, NType 2, SC, NType 2, SM, HType 2, SC, HType 3, SM, NType 3, SM, H
f / f fu
(%)
R/tr/t0 1 2 3 4 5 6
0
10
20
30
40
50
60
70
Type 3, SM, NType 3, SM, H
Unbonded specimens (Type 3)
R/t
Experimental results vs. JSCE
α=0.092
α=0.05
© 2006 The University of Sheffield
Western Bank, Sheffield S10 2TN, UK Miami, Florida, U.S.A.
CICE 2006
The 3rd International Conference on FRP Composites in Civil Engineering
•Thermoplastics could offer a valid solution for on-site bending
•The capacity of the bent portion is not only a function of its geometry
•Values of R/t > 4 guarantee the development of 40% of the ultimate strength
•Need for a rational design method
Final RemarksFinal Remarks