-
8/13/2019 1852606
1/11
Inelastic cyclic behaviourof as-received and pre-corroded
S500s tempcore steelreinforcement
Ch. Alk. Apostolopoulos and C.A. RodopoulosDepartment of
Mechanical Engineering and Aeronautics,
University of Patras, Patras, Greece
Abstract
Purpose Seismic loading can induce significant deformations to
steel reinforcement. The recentapproach suggested by Eurocode 8
indicates that steel reinforcement shall sustain repeated
loading
well within its elastic region, excluding by definition seismic
loading. This paper aims to examine thebehaviour of S500s steel
reinforcement at strain ranges representing strains corresponding
tosmall/medium earthquakes while significant attention has been
paid to cases where the reinforcementhas been corroded as this is
most representative to aged buildings. The work concludes that
thecomplex behaviour of steel reinforcement under low cycle fatigue
conditions can be successfully treatedvia the use of the viscous
stress. The latter is found to be independent to corrosion exposure
while itholds the merits of ductility exhaustion on which most
degradation models are based.
Design/methodology/approach This paper establishes a
relationship between the cumulativeeffect of low cycle fatigue and
that of the viscous stress.
Findings The work identifies that the viscous stress follows an
exponential growth behaviourwhich terminates at a plateau. The
plateau value is found to be independent to corrosion exposure
andstrain rate and hence providing a strong potential for being a
characteristic indicator of the behaviourof steel reinforcement
under realistic inelastic loading.
Research limitations/implications The study is limited to S500s
grade steel. Further study ondifferent steel grades is necessary to
increase the potential of viscous stress.
Originality/value The significance of this paper is the
introduction of viscous stress in an areawhere traditional
approaches of cumulative damage are based on a large number of
empiricalparameters and assumptions.
KeywordsMechanical behaviour of materials, Steel, Stress
(materials), Reinforcement, Viscosity
Paper typeResearch paper
IntroductionSince the 1970s, there is a growing research
interest towards the fatigue response ofhigh-yield steel
reinforcement (from now on called rebars; Tilly, 1979; Highway
Research Board, 1962; ACI Committee 215, 1974). Rebars represent
the basicstrengthening element of steel reinforced concrete, RC,
structures and are responsible forcarrying, distributing and
controlling loads and displacements.
Cyclic loading in the form of constant amplitude or spectra is
mainly due to thegrowing use of RC in bridges, towers, offshore
structures and buildings founded inearthquake zones (ACI Committee
215, 1974; Chang and Mander, 1994). Despite the factthat in the
last 20-30 years rebar production has doubled to 100 million
t/year, while itconstantly retains the 10 per cent of steel
production, the cyclic behaviour of rebars has
The current issue and full text archive of this journal is
available at
www.emeraldinsight.com/1757-9864.htm
IJSI1,1
52
International Journal of Structural
Integrity
Vol. 1 No. 1, 2010
pp. 52-62
q Emerald Group Publishing Limited
1757-9864
DOI 10.1108/17579861011023793
-
8/13/2019 1852606
2/11
received little attention and is mainly concentrated in the
region of elastic loading (S/Ncurves; Hellenic Regulation for the
Technology of Steel in Reinforced Concrete, 2008)regardless of the
design requirements under seismic response conditions where
rebarsare expected to deform into inelastic range and dissipate
energy via a stable hysteretic
behaviour. This is because severe ground motion can result into
cracking of concrete,leaving the rebars governing the response of
the RC section (Filipou et al., 1983).
Although, the cumulative nature of fatigue damage is generally
recognised as animplicit factor controlling total life, current
design practise and codes fail to recognisethe effect of non-peak
inelastic cycles (Chai, 2005). This is particularly hazardous in
thecase of long-duration ground motion or in the case of multiple
seismic events with preor after shocks combined with the main
shock. Accelerograms taken from Mexico Cityindicate that ground
motion events can have a random behaviour both in terms ofmagnitude
and duration (Ordaz and Singh, 1993). In the same work, ground
motionsranging from 55-215 centimeter per square second and with
duration range between 2.9up to 32 second have been reported. The
above two factors represent a critical input interms of identifying
the magnitude of seismic energy contributing to damage inrelation
to the cyclic plastic energy capacity of the structure (Chai et
al., 1998).
The potential of rebars being the self-governing and most
critical constituent phaseto the response of RC structures is
further reinforced in cases where the volumetricexpansion of
corrosion products has caused spalling of concrete cover and
interfacialbond strength degradation (Chang et al., 1999;
Maslehuddin et al., 1983; Fang et al.,2004). Measurements taken
from corroded reinforcement in buildings still in public useand in
locations of significant seismic propensity have shown that mass
loss could beas much as 18 per cent (Apostolopoulos, 2007). In
Apostolopoulos et al. (2006), it wasalso shown that corrosion of
rebars degrades their tensile mechanical strength andductility
properties to levels below the minimum required values set by the
HellenicStandard ELOT 971 (1994).
In this work, the authors attempt to compare and explain the
inelastic cyclic responseof as-received and pre-corroded S500s
grade steel rebar and identify the mechanisms offailure. Herein, it
is also necessary to note that terminologically inelastic cyclic
loading isalso referred as low cycle fatigue or extremely low cycle
fatigue.
Experimental procedure and resultsTempcore S500s ribbed rebar of
nominal diameter 12 millimeter was received from aGreek steel
manufacturer. S500s rebars have extensively been used in Greece
duringthe period 1987-2006. The chemical composition is shown in
Table I. The material hasa minimum yield stress of Rp 500 MPa,
minimum fracture strength ofRm 550 MPa and minimum elongation at
failure of 12 per cent.
The tempcoring process consists of three stages. During the
first stage, hotaustenite at,1,0008C (surface temperature) is
quenched with water down to 2808C. Atthe end of this process the
rebars have an austenite core surrounded by a layer
C P S N Mn Fe
As-received 0.21 0.018 0.030 0.009 0.96 RemainingELOT 1421 (ELOT
971, 1994) ,0.24 ,0.055 ,0.055 ,0.014 Remaining
Table I.Chemical composition of
as-received S500s againstnational standards
Inelastic cyclicbehaviour
53
-
8/13/2019 1852606
3/11
composed of a mixture of austenite and martensite. The duration
of this first stagemainly controls the thickness of the martensite
layer. The second stage involves aircooling. At the beginning of
this stage the temperature of the core is around 900 8Cwhich by
induction reheats the surface to temperatures close to 7808C. This
results into
self-tempering of martensite. The third stage involves final
cooling on a bed. Thisdelivers a quasi-isothermal transformation of
the remaining austenite leading to amixture of two phase
ferrite-pearlite (polygonal ferrite and pearlite) and bainite.
Fromthe above, it is also understood that the percentage of
martensite also depends on thediameter to be produced while the
final product (rebar) should be considered as acomposite material.
A typical cross section of the rebar shown in Figure 1.
Prior to testing, cross sections of the rebars were examined
under scanning electronmicroscope (Philips XL40) after successive
polishing to a surface roughness ofRa , 0.8 micrometer. The
analysis revealed extensive porosity close to the
surface(martensite layer; Figure 2). 3D surface profilometry
revealed that the porosity canreached depths larger or equal to
55-72 micrometer as shown in Figure 3. The numberis only indicative
since the actual tip of the pore is unknown. Energy dispersion
X-rayanalysis was performed at different locations including the
pores. Results from thepores indicate the presence of O and Cu.
Typical results are shown in Figure 4.
Figure 1.Optical view of the phasesconsisting S500s
tempcoreafter Nital etching
Two phase ferrite-pearlite
Martensite
Bainite
Figure 2.Extensive porosity foundin the martensite layer
IJSI1,1
54
-
8/13/2019 1852606
4/11
The amount of oxygen found is high enough as to be primarily
attributed to the largeamounts of oxygen used during the hearth
operation (EUROFER, 2007). Coppercontent should be attributed to
the quality of the scrap metal used.
Strain control cyclic tests were performed in fully reversed
loading without the useof anti-buckling device. The latter was due
to the fact that under realistic seismicconditions, rebars are
prone to buckling between stir-ups. The phenomenon hasreceived
increasing scientific attention in the last years indicating that
thepost-buckling hysteretic behaviour should primarily control the
potential of rebarsto dissipate seismic energy (Chai et al., 1998).
Testing of as-received material wasperformed in a 250KN MTS
servo-hydraulic rig at a frequency of 1 hertz and at threedifferent
(D1ranges, namely: 2, 5 and 8 per cent. The strain amplitude was
chosen inorder to replicate typical seismic response (Franchiet
al., 1996; Pipa and Vercesi, 1996;
Pipaet al., 1994). The above ranges should be considered as
mediocre since values ashigh as D1 28 per cent have been reported
(Sheng and Gong, 1997).
In addition, rebars were exposed in salt-spray environment
according to ASTMB117. This accelerated corrosion tests was
selected as being closer to the case where astructural member of a
building has experienced failure of its concrete cover while
itslocality is close to sea front. The salt solution was prepared
by dissolving five parts bymass of sodium chloride (NaCl) into 95
parts of distilled water. The pH of the salt spraysolution was such
that when dissolved at 358C the solution was in the pH range
of6.5-7.2. The duration of exposure was 45 and 90 days. After
exposure and prior totesting the specimens were cleaned from the
corrosion products. During all tests thehysteretic loop was
recorded. Typical results are shown in Figure 5.
In general the material experiences a continuous softening
degradation mechanism
up to failure. Further analysis is provided in the next section.
The total number ofcycles to failure is shown in Table II.
Herein, it is easily understood that at high strains, the effect
of corrosion incontrolling cyclic loading resistance becomes
independent to corrosion exposure.
Analysis of results and discussionThe breakdown of a hysteretic
loop in isotropic stress (R), backstress (X) and viscousstress (sv)
is known to provide an efficient tool in understanding the
mechanisms
Figure 3.Indicative analysis of pore
morphology
z
55
50
45
40
35
30
25
20
15
5
0
60
65
5045
40
35
30
25
20
15
10
5
0
10
(a) (b)
y/mmx/mm
0.016
00.0040
0.00400.0060
0.00800.01
0.0120.014
0.0080 0.00200
0.012
Notes:(a) The selected pore; (b) the corresponding 3D
morphology
Inelastic cyclicbehaviour
55
-
8/13/2019 1852606
5/11
Figure 4.
Point A
Point B
(a)
(b)
(c)
Notes:(a) Backscattered image of the cross section. Point A
indicates the location for EDX
analysis away from the pore (b) and Point B indicates the EDX
analysis at the pore (c)
IJSI1,1
56
-
8/13/2019 1852606
6/11
governing cyclic failure, especially in the case of large
plastic strains (Rees, 1981;Feaugeas, 1999; Kuhlmann-Wilsdorf and
Laird, 1979; Honycombe, 1968; Cottrell, 1953).The breakdown of a
hysteretic loop is schematically shown in Figure 6.
Plasticstraining in polycrystals develops dislocation walls and
subgrain boundaries. Theabove create long-range internal stresses
due to strain incompatibility and leads to
easier reverse flow. This mechanism is associated to the
backstress (also known asinternal). Additionally, the isotropic
stress is the stress locally required for adislocation to move and
is related to short range stresses like friction stress
(crystallattice, solutes, etc.) and stresses from dislocation
forests. Finally, the viscous stresscontrols the transition from
viscous rupturing to brittle fracture (Honycombe, 1968). Ingeneral,
the behaviour of the viscous stress indicates the creation and
propagation ofmicro-cracks in a stable manner related to the
potential external energy and theinstability (unsteady mode) in
terms of critical crack coalescence. It is also imperative
Figure 5.Typical behaviour of
hysteretic loop
S500s, = 8%, as-received
Strain
0.06 0.04 0.02 0.00 0.02 0.04 0.06
Stress(M
Pa)
800
600
400
200
0
200
400
600
800
Hysteretic loop Hysteretic loop
(a) (b)
S500s, = 5%, as-received
Strain
0.03 0.02 0.01 0.00 0.01 0.02 0.03
Stress(M
Pa)
800
600
400
200
0
200
400
600
800
S500s, = 8%, 45 days
Strain
0.06 0.04 0.02 0.00 0.02 0.04 0.06
Stress(MPa
)
800
600
400
200
0
200
400
600
800
Hysteretic loop Hysteretic loop
(c) (d)
S500s, = 5%, 45 days
Strain
0.03 0.02 0.01 0.00 0.01 0.02 0.03
Stress(MPa
)
800
600
400
200
0
200
400
600
800
Notes:(a)-(b) As-received at strain range of 8 and 5 per cent
and (c)-(d) the corresponding behaviour after
45 days of salt spray exposure; in every case, the loading
sequence is compression tension
Condition D1 2% D1 5% D1 8%
As-received 529 28 1045 days of exposure 335 26 990 days of
exposure 263 23 8
Table II.Average number of
cycles to failure (of threetests) of as-received and
corroded S500s
Inelastic cyclicbehaviour
57
-
8/13/2019 1852606
7/11
to note that the viscous stress can more clearly preserve
information regardingbuckling histories while components X and R
have the tendency to filter them viasuccessive accumulation
effects.
The hysteretic breakdown components are given by:
Xsmax se min
2 1
sv smax 2 se max 2
Rse max 2 se min
2 3
A typical response of viscous stress for the whole range of the
experimental matrix isshown in Figure 7.
Generally speaking, in every case, the viscous stress shows a
similar tendency toincrease, to saturate and finally to decrease.
In the as-received condition it can be clearlyseen that the rate
towards saturation increases with strain. In this case the effect
ofmaterial to control buckling canbe seen at the viscous stress of
the first cycle. The termcontrol is used in quotation marks since
buckling is assumed to take place as a post-yieldcondition. Herein,
at D1 2 per cent the viscous stress initiates at 49 MPa followed
by65 and 85 MPa for D1 5 and 8 per cent, respectively. After 45
days of salt sprayexposure, the corresponding initial viscous
stress values are 80, 96 and 105 MPaindicating increasing tendency
to buckling. In the case, however, of 90 days, the initialviscous
stress value, at around 120 MPa, becomes independent to strain
range indicatingthat the response of the rebars to the first
loading cycle is common. This could beattributed to the fact that
after 90 days of exposure the rebars have developed severestress
concentrations (pitting) which in turn has induced an additional
geometric affectto their buckling behaviour (Apostolopoulos and
Papadakis, 2007).
Figure 6.Partitioning of hystereticloop according to
Cottrell(1953)
R
Elastic part X
semax
semin
e
smaxs
sV
Notes:The parameters smax
, semax
and semin
are the peak stress and the upper and
lower bound of the elastic part of half the hysteretic loop,
respectively
IJSI1,1
58
-
8/13/2019 1852606
8/11
In all cases, the reader can identify that there is a value of
viscous stress atapproximately 150 MPa over which the viscous
stress tends to saturation. Once thisvalue is reached the ability
of the rebar to dissipate energy via positioning andmovement of
dislocations has been exhausted (ductility exhaustion)
whilemicro-cracking is eminent. The development of micro-cracking
will gradually relaxthe viscous stress up to the point where the
density of micro-cracks is such as to lead tolocal interaction
effects (strain amplification) and crack coalescence (failure
eminent). Itis therefore reasonable to assume the viscous stress
value of 150 MPa is critical for theremaining energy dissipation
capacity of S500s. To further reinforce the above rationalit is
imperative to note that:
. The value is independent to corrosion exposure, same value is
obtained also forthe as-received and pre-corroded rebars.
. The value is independent to strain range. The latter is found
barely to control thenumber of cycles to critical value.
Fractographic analysisTo better understand the progression of
damage and the effect of porosity found in theas-received rebar
fractographic analysis was performed. Figure 8(a) shows the
fracture
Figure 7.Behaviour of viscous
stress with strain rangeand exposure time
Cycles to failure
1 10 100 1,000
Viscousstress(MPa)
40
60
80
100
120
140
160
180
(a)
Cycles to failure
1 10 100 1,000
(b)
Viscousstress(MPa)
40
60
80
100
120
140
160
180
200
S500s, = 8%, as-receivedS500s, = 5%, as-receivedS500s, = 2%,
as-received
S500s, = 2%, 45 daysS500s, = 5%, 45 daysS500s, = 8%, 45 days
Cycles to failure
1 10 100 1,000
(c)
Viscousstress(M
Pa)
20
40
60
80
100
120
140
160
180
200
S500s, = 2%, 90 daysS500s, = 5%, 90 daysS500s, = 8%, 90 days
Notes:(a) As-received; (b) 45 days; (c) 90 days; the arrows
indicate the transition towards brittle
fracture; the rectangular section is used to indicate a bound of
values where the viscous stress is
independent to strain range and corrosion exposure
Inelastic cyclicbehaviour
59
-
8/13/2019 1852606
9/11
surface of the as-received rebar at D1 2 per cent. Herein, the
black arrows indicatemultiple-crack initiation. The white arrow
indicates rupture parallel to loading direction.
The rupture can be attributed to the presence of pores found
ahead of the crack tip. Similarbehaviour is shown in the case of
the as-received D1 5 per cent, Figure 8(b). Herein, therole of
porosity is further reinforced by the presence of ruptures found
away from thecracks. In this case, the ruptures were the result of
the higher strain range. Similarbehaviour was found in the case of
as-received rebars at D1 8 per cent. In the case of45 days at D1 5
per cent, failure was due to a synergistic effect of
cracking/ruptures,Figure 8(c) as well as embrittlement zones,
Figure 8(d). Extensive embrittlement was alsofound in the case of
90 days at D1 2 per cent, Figure 8(e). Embrittlement was never
Figure 8.Indicative images takenfrom the fracture surfaceof
as-received andcorroded S500s
(a) (b)
(c) (d)
(e)
Rupture
parallel to
loading
Fatigue cracking
Ruptures
Embrittlement
Crack
Ruputure
Crack
Ruputure
IJSI1,1
60
-
8/13/2019 1852606
10/11
observed in the as-received state. In every case, embrittlement
zones were observed at amaximum depth of 0.34 millimeter and 0.8
millimeter for the case of 45 and 90 days,respectively, (martensite
layer). The embrittlement shall be related to the production
ofhydrogen during the iron dissolution in the pitting process
(Broomfield, 2007).
ConclusionsIn this work, the inelastic cyclic behaviour of
ribbed S500s tempcore steel reinforcementis presented. In the
as-received state the material was found to contain
extensiveporosity potentially due to trapped oxygen. Cu residues
were also found at the poresrelated to the scrap metal. Rebars were
subjected to inelastic fully reversed loading atdifferent strain
ranges and comparison of the hysteretic loops was performed into
thoserepresenting the as-received state and after 45 and 90 days of
slat-spray exposure.
The results indicate that only in the case of D1 2 per cent
there is a cleardegradation due to corrosion in terms of cycles to
failure. In the case ofD1 5 and 8 percent, the total cycles to
failure appear to be independent to corrosion time. Breakdown ofthe
hysteretic loops and examination of the viscous stress indicate
that there is a criticalvalue of 150 MPa after which failure of the
S500s is eminent due to rupturing.Progression towards such critical
value was found to be the main controlling parametertowards the
ability of S500s to dissipate energy with time. Fractographic
analysisrevealed that failure in the as-received state was due to
the synergistic effect of crackprogression and porosity ruptures.
In the corroded state, hydrogen embrittlement zoneswere also
identified as an additional damage mechanism. Yet, the critical
value of theviscous stress was found to be independent to hydrogen
embrittlement predominantlydue to its limited depth of
penetration.
References
ACI Committee 215 (1974), Considerations for design of concrete
structures subjected to fatigue
loading, ACI J. Proc., Vol. 71, pp. 97-121.Apostolopoulos, C.A.
(2007), Mechanical behaviour of corroded reinforcing steel bars
S500s
tempcoreunder low cycle fatigue, Construction and Building
Materials, Vol. 21, pp. 1447-56.
Apostolopoulos, C.A. and Papadakis, V.G. (2007), Consequences of
steel corrosion on theductility properties of reinforcement bar,
Construction and Building Materials, Vol. 22No. 12, pp.
2316-24.
Apostolopoulos, C.A., Papadopoulos, M.P. and Pantelakis, S.G.
(2006), Tensile behaviour ofcorroded reinforcing steel bars
BSt500s, Construction and Building Materials, Vol. 20No. 9, pp.
782-9.
Broomfield, J. (2007), Corrosion of Steel in Concrete, 2nd ed.,
Taylor and Francis, London.
Chai, Y.H. (2005), Incorporating low cycle fatigue model into
duration-dependent inelasticdesign spectra, Earthquake Engng.
Struct. Dyn., Vol. 34, pp. 83-96.
Chai, Y.H., Faifar, P. and Romstad, K.M. (1998), Formulation of
duration-dependent inelasticseismic design spectrum,J. Struct.
Engng (ASCE), Vol. 124 No. 8, pp. 913-21.
Chang, G. and Mander, J. (1994), Seismic energy based fatigue
damage analysis of bridgecolumns: part I evaluation of seismic
capacity, NCEER Technical Report: 000694,National Center for
Earthquake Engineering Research, State University of New
York,Buffalo, NY.
Chang, J.J., Yeih, W. and Huang, R. (1999), Degradation of the
bond strength between rebar andconcrete due to the impressed
cathodic current,J. Marine Sci. Tech., Vol. 7 No. 2, pp. 89-93.
Inelastic cyclicbehaviour
61
-
8/13/2019 1852606
11/11
Cottrell, A.H. (1953), Dislocation and Plastic Flow in Crystals,
Oxford University Press, Oxford.
ELOT 971 (1994), Weldable Steels for the Reinforcement of
Concrete, Hellenic GovernmentGazette, Athens, April 1.
EUROFER (2007), Networking in European Steel Research, Hellenic
Government Gazette,
Athens.
Fang, C., Lundgren, K., Chen, L. and Zhu, C. (2004), Corrosion
influence on bond in reinforcedconcrete, Cement Concr. Res., Vol.
34 No. 11, pp. 2159-67.
Feaugeas, X. (1999), On the origin of tensile flow stress in the
stainless steel AISI 316L at 300K:back stress and effective stress,
Acta Mater., Vol. 47 No. 13, pp. 3617-32.
Filipou, F.C., Popov, E.P. and Bertero, V.V. (1983), Effect of
bond deterioration on hystereticbehaviour of reinforced concrete
joints, Report UCB/EERC-83/19, EarthquakeEngineering Research
Centre, University of California, Berkeley, CA.
Franchi, A., Riva, P., Ronca, P., Roberti, R. and La Vecchia, M.
(1996), Failure modalities ofreinforcement bars in reinforced
concrete elements under cyclic loading, Studi e rocerche,Vol. 17,
pp. 157-87.
Hellenic Regulation for the Technology of Steel in Reinforced
Concrete (2008), HellenicGovernment Gazette 2113/B/13.10.2008,
Hellenic Government Gazette, Athens.
Highway Research Board (1962), The AASHO road test report 4
bridge research, SpecialReport 61 D, Highway Research Board,
National Research Council, Washington, DC.
Honycombe, R.W. (1968),Plastic Deformation of Metals, St Martins
Press, New York, NY.
Kuhlmann-Wilsdorf, D. and Laird, C. (1979), Dislocation
behaviour in fatigue: II friction stressand back stress as inferred
from an analysis of hysteretic loops,Mat. Sci. Engng., Vol. 37,pp.
111-20.
Maslehuddin, M., Ibrahim, I.M., Huseyin, S. and Al-Mana, A.L.
(1983), Influence of atmosphericcorrosion on the mechanical
properties of reinforcing steel, Constr. Build. Mater., Vol. 8No.
1, pp. 35-41.
Ordaz, M. and Singh, S.K. (1993), Source spectra and spectral
attenuation of seismic waves from
Mexican earthquakes, and evidence of amplification in the hill
zone of Mexico City,Bulletin of the Seismological Society of
America, Vol. 82, pp. 24-43.
Pipa, M. and Vercesi, A. (1996), Cyclic tests of grade B400 and
B500 tempcore bars, PREC8Report, LNEC, Lisbon.
Pipa, M., Carvalho, E.C. and Otes, A. (1994), Experimental
behaviour of R.C. Beams with grade500 steel,Proceedings of 10th
European Conference on Earthquake Engineering, Vienna.
Rees, D.W.A. (1981), Anisotropic hardening theory and the
Bauschinger effect,J. Strain Anal.,Vol. 16 No. 2, pp. 85-95.
Sheng, G.M. and Gong, S.H. (1997), Investigation of low cycle
fatigue behavior of buildingstructural steels under earthquake
loading,Acta Metall. Sin. (English letters), Vol. 10No. 1,pp.
51-5.
Tilly, G.P. (1979), Fatigue of steel reinforcement bars in
concrete: a review, Fatigue ofEngineering Materials and Structures,
Vol. 2, pp. 251-68.
Corresponding authorCh. Alk. Apostolopoulos can be contacted at:
[email protected]
IJSI1,1
62
To purchase reprints of this article please e-mail:
[email protected] visit our web site for further
details: www.emeraldinsight.com/reprints
