ML121160414
| ML121160414 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 04/23/2012 |
| From: | Bayrak O University of Texas at Austin |
| To: | Division of Operating Reactor Licensing |
| Lamb John G./NRR/DORL, 415-3100 | |
| References | |
| Download: ML121160414 (33) | |
Text
STRUCTURAL ASSESSMENT OF SEABROOK STATION Role of Concrete Material Testing OGUZHAN BAYRAK, Ph.D., P.E.
Ferguson Structural Engineering Laboratory The University of Texas at Austin April 23, 2012
QUESTIONS FROM NRC Eighteen questions were posed to NextEra and Seabrook Station representatives on April 13, 2012.
DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION 2
Technical questions generally reflect concerns related to performance of concrete materials.
BASIS FOR CONCERNS BASIS FOR CONCERNS
BASIS FOR CONCERNS Mechanical Properties Structural Model Analysis Output fc compressive strength f
il GOOD DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l BASIS FOR CONCERNS 4
ervenka Consulting Limited, 2010 ft tensile strength Ec elastic modulus
poissons ratio BAD UGLY
MECHANICAL PROPERTIES
- Material test data collected from literature Swamy and Al-Asali, 1988 Clark, 1989 Ng and Clark, 1992 Smaoui et al., 2006
- Strength and stiffness reductions are plotted with respect to unrestrained expansions
- Guidelines from Institution of Structural Engineers (ISE) provide a reasonable estimate of lower bound performance DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l BASIS FOR CONCERNS 5
Slides prepared by Dean J. Deschenes.
COMPRESSIVE STRENGTH l fc 75 100 125 150
'c, 28 [%]
0 25 50 0
2 4
6 8
f'c/f' Unrestrained Expansion [%]
N = 68 ISE Guidelines Expansion f'c/f'c, 28 0.5 %
95%
1%
80%
2.5%
60%
5%
60%
DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l BASIS FOR CONCERNS 6
75 100 125 150
't, 28 [%]
Slides prepared by Dean J. Deschenes.
SPLITTING TENSILE STRENGTH l ft 0
25 50 0
2 4
6 8
f't/f' Unrestrained Expansion [%]
N = 86 ISE Guidelines Expansion f't/f't, 28 0.5 %
85%
1%
75%
2.5%
55%
5%
40%
DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l BASIS FOR CONCERNS 7
75 100 125 150 Ec, 28 [%]
Slides prepared by Dean J. Deschenes.
ELASTIC MODULUS l Ec 0
25 50 0
2 4
6 8
Ec/E Unrestrained Expansion [%]
N = 21 ISE Guidelines Expansion Ec/Ec, 28 0.5 %
100%
1%
70%
2.5%
50%
5%
35%
DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l BASIS FOR CONCERNS 8
Slides prepared by Dean J. Deschenes.
POISSONS RATIO l
- Literature review yielded one relevant study
- Limited correlation between and measured expansions Giacco, G., Zerbino, R., Ponce, J.M., and Batic, O.R. Mechanical behavior of concretes damaged by alkali-silica reaction. Cement and Concrete Research Vol. 38 (2008): 993-1004.
0.00 0.05 0.10 0.15 0.20 0.25 0.00 0.05 0.10 0.15 0.20 Poisson's Ratio, Unrestrained Expansion [%]
Control R2 R3 R4 DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l BASIS FOR CONCERNS 9
PERCEPTION Mechanical Properties Structural Model Analysis Output fc compressive strength f
il GOOD
?
DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l BASIS FOR CONCERNS 10 ervenka Consulting Limited, 2010 ft tensile strength Ec elastic modulus
poissons ratio BAD UGLY
?
?
Slides prepared by Dean J. Deschenes.
REALITY It has to be realized that any strength test conducted on a specimen quantifies the performance of the material in relation to that method of test only and does not necessarily reflect the performance of the material in its structural context. The significance of this for the assessment of structures [subject to ASR] is that no reliance should be structures [subject to ASR] is that no reliance should be placed on the values obtained from any one test and that commonly accepted procedures, such as the cube crushing test, may not indicate the value to be used in a normal design check.
Clayton et al., 1990 DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l BASIS FOR CONCERNS 11
STRUCTURAL CONTEXT STRUCTURAL CONTEXT
INSIGHTS FROM FSEL RESEARCH Full-scale study conducted to establish effects of ASR on shear strength of beams with transverse reinforcement.
DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l STRUCTURAL CONTEXT 13 1.2 % +
RESTRAINED EXPANSION Transverse reinforcement restrained ASR-related expansions, resulting in the development of confining stresses.
b fPCD = (2Fbar)÷ (bs)
Fbar DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l STRUCTURAL CONTEXT 14
RESTRAINED EXPANSION DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l STRUCTURAL CONTEXT 15
UNRESTRAINED EXPANSION DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l STRUCTURAL CONTEXT 16
STIFFNESS IMPLICATIONS 6
8 10 12 pan Shear, V/bdf'c 0
2 4
0 0.2 0.4 0.6 0.8 1
1.2 Normalized Test S Deflection at Load [in]
DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l STRUCTURAL CONTEXT 17
67 1.98 2.12 1 5 2.0 2.5 3.0 y / Predicted Capacity STRENGTH IMPLICATIONS Sectional Shear Vn = Vc + Vs vs. nR1, 1.00 1.54 1.6 vs. ACI, 1.41 0.0 0.5 1.0 1.5 nR1 R1 R2 Experimental Capacity DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l STRUCTURAL CONTEXT 18
[fc = 7.2 ksi]
[fc = 4.5 ksi]
[fc = 4.2 ksi]
CORRELATION TO MATERIAL TESTS nR1 R1 R2 DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l STRUCTURAL CONTEXT 19 t,max 0.0%
0.2%
0.7%
fc 7.2 ksi 4.5 ksi 4.2 ksi ft 640 psi 430 psi Vtest 276 kips 336 kips 353 kips
Slides prepared by Dean J. Deschenes.
RELEVANCE OF MATERIAL TEST DATA The behavior of plain concrete affected by ASR is not necessarily indicative of structural performance.
Free Expansion Restrained Expansion DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l STRUCTURAL CONTEXT 20
ASSESSMENT APPROACHES ASSESSMENT APPROACHES
Slides prepared by Dean J. Deschenes.
ASSESSMENT APPROACHES CORE-BASED ANALYSES FULL-SCALE TESTING DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l ASSESSMENT APPROACHES 22
Slides prepared by Dean J. Deschenes.
CORE-BASED ANALYSES ASR-Induced Forces Mechanical Properties Relevant Code Expressions In-Situ Strength
DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l ASSESSMENT APPROACHES 23 Estimated Expansion Structural Analysis Reinforcing Details Forces Concrete Core Tests fc ft Ec Stiffness Damage Expansion Potential
Cores extracted from a reinforced concrete structure are not representative of in-situ conditions.
Slides prepared by Dean J. Deschenes.
APPLICABILITY OF CORE TESTS DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l ASSESSMENT APPROACHES 24 Compression Test Expansion Test
Test results will be influenced by the coring direction as it relates to structural geometry and sources of restraint.
Slides prepared by Dean J. Deschenes.
APPLICABILITY OF CORE TESTS
DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l ASSESSMENT APPROACHES 25
Splitting Tensile Tests
Test results will be influenced by the coring direction as it relates to structural geometry and sources of restraint.
Slides prepared by Dean J. Deschenes.
APPLICABILITY OF CORE TESTS
DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l ASSESSMENT APPROACHES 26
Splitting Tensile Tests 90°?
Magnitude and direction of ASR-related cracking in structures is strongly influenced by a number of factors.
NON-ISOTROPIC EXPANSION
- Internal Restraints
- Reinforcement Pattern
- Prestressing
- Post-Tensioning
- Post-Tensioning
- External Restraints
- Superimposed Loads
- Boundary Conditions
- Geometric Discontinuities Lawrence et al., 1999 DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l ASSESSMENT APPROACHES 27
Field implementation of test results requires development of correlation between free and restrained expansions.
Slides prepared by Dean J. Deschenes.
APPLICABILITY OF CORE TESTS DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l ASSESSMENT APPROACHES 28
?
Definitive assessments may be obtained by replicating critical structural details and deterioration within the laboratory.
Slides prepared by Dean J. Deschenes.
FULL-SCALE TESTING DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l ASSESSMENT APPROACHES 29 Accelerated Deterioration Continuous Monitoring Current and Future Damage
Slides prepared by Dean J. Deschenes.
FULL-SCALE TESTING
- ISE structural assessment guidelines were developed on the basis of accelerated laboratory tests DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l ASSESSMENT APPROACHES 30
Slides prepared by Dean J. Deschenes.
FULL-SCALE TESTING
- ISE structural assessment guidelines were developed on the basis of accelerated laboratory tests
- Proof testing will provide the A
A Section A-A Reinforcement Anchorage DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l ASSESSMENT APPROACHES 31 most meaningful assessment of critical structural details Reinforced Concrete MacGregor & Wight, 2005 Reinforced Concrete MacGregor & Wight, 2005 Shear Strength
Slides prepared by Dean J. Deschenes.
FULL-SCALE TESTING
- ISE structural assessment guidelines were developed on the basis of accelerated laboratory tests
- Proof testing will provide the DR. OGUZHAN BAYRAK, PE STRUCTURAL ASSESSMENT OF SEABROOK STATION l ASSESSMENT APPROACHES 32 most meaningful assessment of critical structural details
- Full-scale structural testing is the most definitive form of structural assessment from Containment Integrity Research at Sandia National Laboratories Nuclear Regulatory Commission, 2006
QUESTIONS QUESTIONS