JSCE specifications on stainless JSCE specifications on stainless steel bars and new steel bars and new anchorage/splice technologies anchorage/splice technologies Takumi Shimomura Nagaoka University of Technology JAPAN SOCIETY OF CIVIL ENGINEERS JAPAN SOCIETY OF CIVIL ENGINEERS
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JSCE specifications on stainless JSCE specifications on stainless steel bars and newsteel bars and newanchorage/splice technologiesanchorage/splice technologies
Takumi ShimomuraNagaoka University of Technology
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Standard Specifications for Standard Specifications for Concrete StructuresConcrete Structures
2007 editionDesignMaterials and ConstructionMaintenanceDam ConcreteTest Methods and Specifications for Concrete
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Recommendations and Recommendations and GuidelinesGuidelines
Recent publications:Recommendations on Environmental Performance Verification for Concrete Structures (Draft)Recommendations for Mix Design of Fresh Concrete and Construction Placement related Performance EvaluationRecommendations for Design and Construction of High Performance FiberReinforced Cement Composite with Multiple Fine Cracks (HPFRCC)Ancient Roman Concrete
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Publications in EnglishPublications in EnglishMost JSCE Standard Specifications for Concrete Structures, Recommendations and Guidelines have been translated into English.You can purchase them from our web site. http://www.jsce.or.jp/
JSCE Standards on Test Method for Diffusion Coefficient of Chloride Ion in Concrete
RECOMMENDATIONS FOR SHOTCRETING (DRAFT)
STANDARD SPECIFICATIONS FOR CONCRETE STRUCTURES-2002 "Structural Performance Verification"
STANDARD SPECIFICATIONS FOR CONCRETE STRUCTURES -2002 "Seismic Performance Verification"
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Topics todayTopics today
Recommendations for Design, Fabrication and Evaluation of Anchorages and Joints in Reinforcing Bars [2007] (August 2007)Recommendations for Design and Construction of Concrete Structures Using Stainless Steel Bars –Draft- (August 2008)
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Anchorages and Joints in Reinforcing Bars
Anchorages and Joints in Anchorages and Joints in Reinforcing BarsReinforcing Bars
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Background of revision of the Background of revision of the guidelineguideline
Anchorages and Joints in Reinforcing Bars
Previous guideline on joints in reinforcing bars was published in 1982.Reinforcing bar arrangement has become denser due to highly required seismic performance.A lot of technologies of anchorages and joints have been developed.The design methods of concrete structures have been shifted to the performance-based design, recently.
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Anchorages and Joints in Reinforcing Bars
Characteristics of new editionCharacteristics of new edition
Anchorages in reinforcing bars are included as well as joints.Joints are evaluated not only by their performance but also considering the reliability of construction and inspection, which are practically significant.
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Anchoring methodsAnchoring methods
Mechanical anchoring methods involving the installation of anchorage elements at the ends of reinforcing bars,Methods using the bond strength between concrete and reinforcing bars
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Anchorages and Joints in Reinforcing Bars
mechanical anchorage
bonding
bearing
conventional anchorage
Development of mechanical Development of mechanical anchorageanchorage
Anchorages and Joints in Reinforcing Bars
Mechanical anchorage was developed to reduce complexity in arrangement of reinforcement.Benefit:
improvement of constructabilityshorten construction periodcost downimprovement of reliability in compaction of concrete
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Variation in mechanical Variation in mechanical anchorageanchorage
Flash-welded anchorage
Threaded deformed bar anchorage
Friction-welded anchorage
Enlarged-ended bar anchorage
Anchorages and Joints in Reinforcing Bars
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Verification method for Verification method for anchorageanchorage
Anchorages and Joints in Reinforcing Bars
If the anchorage under consideration follows the performance requirements for the performance items, which is necessary at the design stage such as strength and pullout resistance, high-stress cyclic loading capacity, and fatigue strength, the mechanical anchorage may be needed for design purposes to be equivalent to a standard hook.
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Performance evaluation criteria Performance evaluation criteria for anchorages for anchorages
steel rod or invar wire
transducer
reference hook anchorage specimen
mechanical anchorage specimen
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Anchorages and Joints in Reinforcing Bars
Examples of test results of Examples of test results of static strength (D16)static strength (D16)
0.25 0.50 0.75 1.00 1.25
100
200
300
400
500
0
pullout (mm)
stre
ss(N
/mm
2 )
Mechanical anchorage reference hook
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Anchorages and Joints in Reinforcing Bars
(2)<(3)
(1) difference in pullout under upper limit stress during thirtieth loading cycle between mechanical anchorage and reference hook
(2) difference in pullout of mechanically anchored reinforcing bar between thirties and first loading cycles
(3) difference in pullout of reinforcing bar anchored by reference hook between thirtieth and first loading cycles
pullout
(2)(3)
stre
ss
0.95fyn
0.02fyn
mechanical anchorage
reference hook anchorage
(1)
Anchorages and Joints in Reinforcing Bars
Examples of results of Examples of results of highhigh--stress stress cyclic loading testcyclic loading test
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Pressure-welded jointing
Welded jointing
Lap jointing (conventional)
concrete
Mechanical jointing
General (for joints)General (for joints)
Anchorages and Joints in Reinforcing Bars
(1) It must be verified that all joint zones meet the performance requirements.
(2) The steel joints to be used must be selected appropriately according to such factors as the type of steel to be used as base metal, bar diameter, the state of stress, joint location and joint performance requirements.
(3) For all materials to be used for steel joints, it must be verified in advance that those materials conform to relevant quality standards such as JIS.
(4) When steel joints are used, their reliability resulting fromconstruction and inspection must be taken into consideration.
(5) Steel joints should not be located as much as possible in cross sections in which large stresses occur.
(6) Steel joints should be spaced apart and should not be concentrated in a cross section as much as possible.
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Examples of construction of jointExamples of construction of joint
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Anchorages and Joints in Reinforcing Bars
Examples of inspection of jointExamples of inspection of jointAnchorages and Joints in Reinforcing Bars
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Reliability resulting from Reliability resulting from construction and inspection construction and inspection
Anchorages and Joints in Reinforcing Bars
The reliability of reinforcing bar joints resulting from construction and inspection is classified in three classes: I, II and III.
Reliability determined by the reject rate of joints
Reliability of jointReject rate of joints considering reliability of construction and inspection
reject rate of joints
Level I The reject rate of joints is extremely low. 0.3% or less
Level II The reject rate of joints is low. 5% or less
Level III The reject rate of joints is at or below a certain level.
15% or less
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Reliability of joint affected by Reliability of joint affected by construction and inspection construction and inspection
Reliability of jointReliability of joint
Attentiveness of construction workers
Qualification Response to evaluation result
Human action
Accuracy Human error
Sampling ratio
Reliability of constructionReliability of construction
Reliability of inspectionReliability of inspection
Skills of construction workers
Anchorages and Joints in Reinforcing Bars
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Construction level and Construction level and inspection levelinspection level
Anchorages and Joints in Reinforcing Bars
(i) Construction levels1: The probability of occurrence of a defective joint is extremely low,
and few defective joints are produced unintentionally.2: The probability of occurrence of a defective joint is sufficiently low.3: The probability of occurrence of a defective joint is low.
(ii) Inspection levels1: The probability of judging a defective joint to be acceptable is
extremely low, and, as a general rule, a supervisor inspects all joints and few defective joints are overlooked.
2: The probability of judging a defective joint to be acceptable is sufficiently low.
3: The probability of judging a defective joint to be acceptable is low.
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Anchorages and Joints in Reinforcing Bars
Reliability of joints determined by Reliability of joints determined by construction and inspection levelsconstruction and inspection levels
Inspection levelConstruction level
1 2 3
1 Level I Level I Level II
2 Level I Level II Level III
3 Level II Level III Level III
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Stainless Steel Bars
Stainless Steel BarsStainless Steel Bars
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Background of stainless steel Background of stainless steel barsbars
Reinforcement corrosion in concrete due to chloride ingress or carbonation is most serious problem to reduce durability of concrete structures in Japan.Countermeasure to reinforcement corrosion:
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
StressStress--strain curvesstrain curves
0
100
200
300
400
500
0 5000 10000 15000 20000
ひずみ(×10-6)
応力
(N/m
m2)
D19
D25
SD345(D19)
0
100
200
300
400
500
0 5000 10000 15000 20000
ひずみ(×10-6)
応力
(N/m
m2)
D19
D25
SD345(D19)
0
100
200
300
400
500
0 5000 10000 15000 20000
ひずみ(×10-6)
応力
(N/m
m2)
D25
D19
SD345(D19)
0
100
200
300
400
500
0 5000 10000 15000 20000
ひずみ(×10-6)
応力
(N/m
m2)
D25
D19
SD345(D19)
similar with conventional
strain hardening
strain (x10-6) strain (x10-6)
strain (x10-6)strain (x10-6)
stre
ss (
N/m
m2 )
stre
ss (
N/m
m2 )
stre
ss (
N/m
m2 )
stre
ss (
N/m
m2 )
SUS340 -SD SUS316 -SD
SUS410 –SD295 SUS410 –SD345JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Stainless Steel Bars
Strength and stressStrength and stress--strain strain model for designmodel for designStress-strain model for stainless steel reinforcement
Definition of strength of stainless steel reinforcement
ε
σ
0
f yd
σ=E s・ ε
σ=f yd +E u ・ (ε-ε y )
ε y ε
σ
0
f yd
σ = E s・ ε
σ= f yd
SUS410-SD295 except SUS410-SD295
ε
σ
0
f yk
0.2%
E s
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Stainless Steel Bars
Stainless Steel Bars
Fatigue propertiesFatigue propertiesSUS304-SD, SUS316-SD: higher fatigue strengthSUS410-SD: fatigue strength is close to estimated by JSCE conventional design equation
100
150
200
250
300
350
400
0 500 1,000 1,500 2,000
破断繰返し数N(×103)
応力
振幅
σ0(N
/m
m2)
示方書式
SUS304-SD
SUS316-SD
SUS410-SD
100
150
200
250
300
350
0 500 1,000 1,500 2,000
破断繰返し数N(×103)
応力
振幅
σ0(N
/m
m2)
示方書式
SUS304-SD
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
number of loading at fracture N (x103)
stre
ss a
mpl
itude
(N
/mm
2 )
JSCE eq.JSCE eq.
stre
ss a
mpl
itude
(N
/mm
2 )
JSCE equation can be used as well as conventional reinforcement.
sud
spk
a
srd fNf γ
σ⎟⎟⎠
⎞⎜⎜⎝
⎛−= 110190s
ud
spk
a
srd fNf γ
σ⎟⎟⎠
⎞⎜⎜⎝
⎛−= 110190
number of loading at fracture N (x103)D19 D35
Test on seismic performance of RC member using stainless steel
reversed cyclic loading test of RC column specimen
-200
-150
-100
-50
0
50
100
150
200
-150 -100 -50 0 50 100 150
変位(mm)
荷重
(k
N)
displacement (mm)
load
(kN
)
lateralreinforcement (SUS304, D13)
longitudinal reinforcement (SUS304, D25)
loading point
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Stainless Steel Bars
Stainless Steel Bars
LCC assessment of RC LCC assessment of RC structure using stainless barsstructure using stainless bars
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
LCC of structures using SUS304-SD, SUS316-SD, SUS410-SD are just equal to their Initial Cost because of no corrosion.Due to the maintenance cost, LCC of conventional structures are higher than that of structures using stainless steel.
Stainless Steel Bars
Results of LCC assessmentResults of LCC assessment((CC00=13kg/m=13kg/m33 ))
LCC of structures using SUS304-SD, SUS316-SD are just equal to their Initial Cost because of no corrosion.Structure using SUS410-SD need to be repaired before 43 year due to reinforcement corrosion, which will affect its LCC.
Stainless Steel Bars
Stainless Steel Bars
Examples of concrete structures Examples of concrete structures using stainless steel using stainless steel reinforcementreinforcement
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
LeveeLeveeStainless Steel Bars
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS
Aomori Prefecture MuseumAomori Prefecture Museum
JAPAN SOCIETY OF CIVIL ENGINEERSJAPAN SOCIETY OF CIVIL ENGINEERS