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SCI P427 - Structural Steel Reuse: assessment, testing and design principles.

Authors:
  • Pell Frischmann

Abstract

This document has been prepared to help facilitate the reuse of structural steel sections reclaimed from existing building structures. The principal focus of this protocol is the reclamation and reuse of individual members within a new structure, rather than the reuse of an entire building structure in a new location. The protocol proposes a system of investigation and testing to establish material characteristics, with advice for designers completing member verifications of reclaimed steelwork. The protocol places important responsibilities on the holder of reclaimed steelwork including identification, assessment, control procedures and declarations of conformity. The protocol is founded on the principle that given appropriate determination of material characteristics and tolerances, re-fabricated reclaimed steelwork can be fabricated and CE marked in accordance with BS EN 1090[1].
1
STRUCTURAL
STEEL REUSE
ASSESSMENT, TESTING AND DESIGN PRINCIPLES
2
3
STRUCTURAL
STEEL REUSE
ASSESSMENT, TESTING AND DESIGN PRINCIPLES
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Publication Number: SCI P427
ISBN 13: 978-1-85942-243-4
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i
D G Brown BEng, CEng, MICE
R J Pimentel MEng, MSc
M R Sansom BEng, PhD, CEnv, MICE
SCI PUBLICATION P427
STRUCTURAL
STEEL REUSE
ASSESSMENT, TESTING AND DESIGN PRINCIPLES
iii
The environmental advantages of re-using reclaimed structural steel are considerable,
compared to the common practice of recycling by re-melting scrap. There are also
potential cost savings compared to the use of new steel.
This protocol recommends data collection, inspection and testing to ensure that
reclaimed structural steelwork can be reused with condence. Certain conservative
assumptions about the material characteristics may be made, or testing should be
undertaken to determine the properties with greater condence.
The reuse of reclaimed steel is limited to applications where the reclaimed members
were not subjected to fatigue, for example, steelwork from bridges. Reclaimed steel
from structures which have experienced extreme loads such as re or impact are not
considered to be suitable for reuse and therefore are not covered by this protocol. Steel
used in construction before 1970 is excluded from these recommendations.
This protocol recommends that steelwork is reclaimed in groups of members that
have the same form, size, original function and are from the same source structure,
as described in Section 6.1. Assembling groups in this way allows certain material
properties to be established by testing one or more representative members from
the group.
It is recommended that the only modication necessary for structural design is to verify
buckling resistance using γM1,mod=1.15 γM1. This might lead to changes in the structural
solution required for a given design scenario (for example additional restraints might
be required) but not necessarily a change in member size, as member buckling might
not be the critical verication. Within the protocol scope, described in Section 2, the
use of γM0 and γM2 values proposed in the National Annex to EN 1993-1-1 is considered
to be appropriate for reclaimed steel.
This protocol notes that material characteristics declared under CE marking procedures
are designed to ensure that the material is as specied in design. When using
reclaimed steel, the design is based on the material properties (either tested or based
on conservative assumptions), maintaining the relationship between the design
assumptions and material resistance with an adequate level of reliability.
This protocol recommends that re-certied and re-fabricated reclaimed structural
steelwork can be CE Marked in accordance with BS EN 1090.
SUMMARY
iv
v
CONTENTS
SUMMARY iii
1 INTRODUCTION 1
2 OBJECTIVE AND SCOPE 3
2.1 Drivers for re-use of structural steelwork 3
2.2 Reclaim, stock and re-use process 4
2.3 Alternative specification of source material 5
3 CE MARKING OF RECLAIMED
STRUCTURAL STEELWORK 7
3.1 CE Marking 7
3.2 CE Marking of reclaimed steel 8
3.3 Declaration of properties 8
3.4 Material properties to be declared for
reclaimed steelwork 8
3.5 Commentary on the required properties 9
4 DESIGN RECOMMENDATIONS 13
4.1 Structure scope 13
4.2 Ductility and residual strains 13
4.3 Global analysis 13
4.4 Cross sectional resistance 14
4.5 Buckling resistance 14
4.6 Steel toughness and sub-grade 14
4.7 Revised thickness limits for use
outside the UK 15
4.8 Connection design 15
5 ASSESSMENT OF RECLAIMED
STEELWORK FOR REUSE 19
5.1 Introduction 19
5.2 Preliminary assessment 19
5.3 Admissibility of reclaimed steelwork 19
5.4 Assessment and initial data collection 20
5.5 Inspection requirements undertaken
by stock holder 0
6 RESPONSIBILITIES OF THE
HOLDER OF STOCK 23
6.1 Member grouping 23
6.2 Records 24
6.3 Declarations 24
7 TEST PROGRAMME 27
7.1 Introduction 27
7.2 Non-statistical and statistical testing 27
8 FABRICATION ISSUES 31
8.1 General comments 31
8.2 Existing coatings on reclaimed steelwork 31
8.3 Bolt holes and welds in reclaimed steel 31
8.4 Existing connections 32
9 REFERENCES 35
APPENDIX A
DESIGN RECOMMENDATIONS 39
A.1 ENV 1993-1-1 background 39
A.2 The value of
γM1
39
A.3 The values of
γM0
and
γM2
40
A.4 Consequence class 1 structures 40
A.5 Consequence class 2 structures 40
A.6 Consequence class 3 structures 40
APPENDIX B
DATA RECORDS AND INFORMATION 43
B.1 Data records 43
APPENDIX C
STRENGTH AND ELONGATION 47
C.1 Measured strength and assumed
steel grade 47
C.2 Non-destructive hardness tests 48
C.3 Destructive tensile tests: non-statistical
and statistical testing regimes 50
APPENDIX D
IMPACT TOUGHNESS 53
D.1 Destructive tests 53
APPENDIX E
CHEMICAL COMPOSITION 55
E.1 Introduction 55
E.2 Non-destructive tests to establish
chemical composition 55
E.3 Destructive tests to establish chemical
composition 55
APPENDIX F
GEOMETRIC TOLERANCES 57
F.1 Cross section dimensions 57
F.2 Bow imperfections (lack of straightness) 57
vi
1
This document has been prepared to help facilitate the reuse of structural steel
sections reclaimed from existing building structures. The principal focus of this protocol
is the reclamation and reuse of individual members within a new structure, rather than
the reuse of an entire building structure in a new location.
The protocol proposes a system of investigation and testing to establish material
characteristics, with advice for designers completing member verications of reclaimed
steelwork. The protocol places important responsibilities on the holder of reclaimed
steelwork including identication, assessment, control procedures and declarations of
conformity.
The protocol is founded on the principle that given appropriate determination of
material characteristics and tolerances, re-fabricated reclaimed steelwork can be
fabricated and CE marked in accordance with BS EN 1090[1].
INTRODUCTION
2
3
The objective of this protocol is to facilitate the increased uptake of structural
steel reuse. Reuse involves reclaiming steelwork, establishing material properties,
maintaining records of the reclaimed material and declaring material properties. This
protocol also covers the use of material manufactured to an alternative specication,
i.e. not manufactured to a European product standard.
The scope of this protocol covers steel reclaimed from any geographical location, as
material characteristics are established by test. Although the primary focus of the
protocol assumes the reclaimed steelwork will be used in construction in the UK (and
thus British Standards are referenced), the document has been prepared to facilitate
reuse in any country which has adopted the Eurocode suite of Standards.
The scope of this protocol is limited to:
Steelwork erected after 1970;
Steelwork which has not been subject to fatigue, e.g. not reclaimed from bridges;
Steelwork which has not been subject to signicant strains, e.g. plastic hinges;
Steelwork without signicant loss of section due to corrosion;
Steelwork which has not been exposed to re.
This protocol anticipates that the primary use of reclaimed steelwork will be as plain
members, i.e. with existing connections removed or redundant, used within a new
structure. However, the reuse of steelwork with existing connections is not excluded,
nor the reuse of a complete (or partial) structure, re-erected in a different location.
2.1 Drivers for re-use of structural steelwork
Structural steel sections are robust and dimensionally stable elements that are
generally bolted together to form structural assemblies which are inherently
demountable. As such, structural steel is seen as an obvious candidate for reclamation
and reuse as opposed to the current, common practice of recycling by remelting.
Reusing structural steel yields signicant environmental savings compared to recycling.
There is growing pressure on the construction industry to be more resource efcient,
reduce waste and to lower embodied carbon impacts. More recently, circular economy
concepts are being promoted, particularly at the EU level, with a roadmap developed to
support a shift towards a resource efcient, low carbon European economy. Increased
OBJECTIVE AND SCOPE
4
OBJECTIVE AND SCOPE
structural steel reuse will support both of these aims and stimulate new business
opportunities in the UK in particular, by substituting steel imports.
Although new steel and scrap steel prices are volatile, analysis reveals that the long-
term price (2000-2016) differential between the cost of UK structural steel and scrap
sections is over £300 per tonne. This represents the potential prot opportunity
through structural steel reuse. Although additional costs (relative to recycling) will be
incurred through deconstruction, testing, storage, re-fabrication, etc. structural steel
reuse can yield cost savings or at least provide an economical feasible alternative to
the use of ‘new’ structural steel.
This protocol aims to help facilitate the widespread uptake of structural steel reuse.
2.2 Reclaim, stock and reuse process
Although the procedures described in this protocol relate to steel sections reclaimed
from an existing structure, the process is equally applicable to unused ‘new’ steel,
for example, resulting from a cancelled project. Fabricated (but not erected) steel is
likely to have known provenance and comprehensive documentation, which will be
reected in less onerous design constraints compared to reclaimed steelwork. If steel
has been fabricated but not erected, it is likely that material properties and fabrication
procedures will be documented and can be assumed to be appropriate. This is
especially true for steelwork fabricated since July 2014, when CE marking of structural
steelwork according to BS EN 1090 became mandatory.
The overall process from reclamation of steelwork to re-use in another structure is
summarised below. Subsequent sections and appendices provide more detail.
Overall process
1. A building is offered for salvage of the steelwork for reuse. Considerations include
the acceptability of the source material, (see Section 5.3), the demountability of
the structure, the increased cost of careful demolition, etc.
2. A business case is established between the stockholder and the company
responsible for demolition.
3. Important details of the anticipated reclaimed steel are recorded as described in
Section 5.4.
4. Reclaimed steelwork is received by the stock holder, grouped and listed as
described in Section 6.1. The necessary grouping has an important impact on the
extent of testing required.
5. Members are inspected and tested in accordance with Section 7, with the
information appended to the stock data. The testing regime involves non-
destructive and/or destructive testing, with the opportunity to make conservative
assumptions about certain material characteristics. The seller of the stock is
responsible for declaring the necessary characteristics as the material is sold.
5
6. Material is sold, with an accompanying declaration of the material characteristics
by the holder of the reclaimed stock. The declaration covers all relevant material
properties which allow the fabricated steelwork to be CE marked to BS EN 1090
(see Section 3).
7. Structural design and member verication are completed with certain
modications, following the recommendations provided in Section 4.
2.3 Alternative specication of source material
Unused (not fabricated) steel might be placed on the market having been
manufactured to an alternative product standard, for example steel manufactured
to an American, or offshore manufacturing standard. This unused material would be
expected to have appropriate original certication declaring the material properties.
If the material can be shown to comply in all respects with a weldable structural steel
reference standard (as listed in Section 1.2.2 of BS EN 1993-1-1[2]), and tolerances
within the limitations of BS EN 1090-2[3], the material can be used in design, using the
procedures specied in BS EN 1993-1-1 and without modication of the γM1 value as
proposed for reclaimed steelwork (see Section 4.5).
A declaration of the material properties must be provided by the stockholder.
6
7
3.1 CE Marking
CE Marking of structural steelwork is addressed in BS EN 1090-1. All fabricated
steelwork placed on the EU market must be CE Marked. Basic material (rolled sections,
plate, etc.) must be CE Marked to the relevant product standard and the fabricated
steelwork must be CE Marked to BS EN 1090-1.
Steel manufacturers declare that their product meets the relevant product standard;
steelwork contractors declare that the fabricated steelwork meets the requirements of
the execution standards BS EN 1090-1 and BS EN 1090-2.
BS EN 1090-2 generally anticipates that ‘new’ steelwork is used in construction works,
as stated in clause 5.1. Reclaimed steelwork must clearly be treated differently, as it
might have been manufactured to a withdrawn standard and is most unlikely to have
any documented test results from time of manufacture. BS EN 1090-2 sanctions the
use of other materials by stating that: “If constituent products that are not covered by
the standards listed are to be used, their properties are to be specied. The relevant
properties to be specied shall be taken from the following list:
a. Strength (yield and tensile);
b. Elongation;
c. Stress reduction of area requirements (STRA), if required;
d. Tolerances on dimensions and shape;
e. Impact strength or toughness, if required;
f. Heat treatment delivery condition;
g. Through thickness requirements (Z-quality), if required;
h. Limits on internal discontinuities or cracks in zones to be welded if required.
In addition, if the steel is to be welded, its weldability shall be declared as follows:
i. Classication in accordance with the materials grouping system dened in
CEN ISO/TR 15608 or;
j. A maximum limit for the carbon equivalent of the steel, or;
k. A declaration of its chemical composition in sufcient detail for its carbon
equivalent to be calculated.”
CE MARKING
OF RECLAIMED
STRUCTURAL
STEELWORK
8
CE MARKING OF RECLAIMED
STRUCTURAL STEELWORK
BS EN 1090-2 requires that documentation must be used to declare the relevant
material characteristics. It is mandatory that this documentation is provided by the
holder of the stock when selling the material.
3.2 CE Marking of reclaimed steel
There will be no difference in the fabrication processes, procedures, standards or
tolerances for either new steel or reclaimed steel. It is therefore appropriate that
re-fabricated, reclaimed structural steelwork can be CE Marked in accordance with
BS EN 1090.
In addition to careful control of the fabrication process, material properties must be
declared according to BS EN 1090-2 clause 5.1. When using reclaimed steel, this is
the stockholder’s responsibility.
3.3 Declaration of properties
The purpose of declaring material properties is so that the material used in
construction meets the appropriate standard and that properties required by design
are conrmed, e.g. the required material strength assumed in the member verications
has actually been provided.
Generally, a structural designer species certain material characteristics (which have
been assumed in the design process), which are then conrmed as actually used in
the structure by the declaration of properties. With reclaimed structural steel, the
relationship is reversed, so that the design verications are based on the properties
(either tested or conservatively assumed) of the reclaimed elements. In either
approach the objective of the declaration of material properties is to ensure that the
design assumptions are compatible with the material.
The requirements of BS EN 1090-2 and the testing regime for reclaimed steelwork are
discussed in Section 3.4.
3.4 Material properties to be declared for
reclaimed steelwork
The test regime described in Section 7 is intended to allow the necessary material
properties according to BS EN 1090-2 clause 5.1 to be declared, based on dimensional
survey, by non-destructive tests, by destructive tests or by making conservative
assumptions. A summary of the necessary material properties and how they are to be
assessed is presented in Table 3.1.
Section 3.5 provides a commentary on each material property that must be declared.
9
3.5 Commentary on the required properties
3.5.1 Strength
Yield strength and ultimate strength should be determined by non-destructive and
destructive tests. The use of non-destructive tests is limited to establishing the steel
grade. The declared yield strength and ultimate strength should be the values specied
in product standards appropriate for that grade, not the values determined from the
tests. Because the protocol is limited to steel used in construction after 1970, the yield
strengths and ultimate strengths taken from the product standard are considered to
be reliable.
Non-destructive testing is also used to identify any inconsistencies between members
within a group. Within this protocol, a group is a number of reclaimed members, having
Item Property To be
declared Procedure
a) Strength (yield and tensile) Ye s Determined by destructive and non-
destructive tests.
b) Elongation Yes Determined by destructive tests.
c) Stress reduction of area
requirements (STRA)
If
required Generally not required to be declared.
d) Tolerances on dimensions
and shape Ye s Based on dimensional survey.
e) Impact strength or
toughness
If
required
If required, determined by destructive
tests. Conservative assumption as the
default.
f) Heat treatment delivery
condition Yes Conservative assumption as the default.
g) Through thickness
requirements (Z-quality)
If
required Generally not required to be declared.
h)
Limits on internal
discontinuities or cracks in
zones to be welded
If
required Generally not required to be declared.
In addition, if the steel is to be welded, its weldability shall be declared as follows:
i)
Classification in accordance
with the materials grouping
system defined in
CEN ISO/TR 15608, or
Yes
Not applicable for reclaimed steelwork.
j)
A maximum limit for the
carbon equivalent of the
steel, or;
Maximum to be declared from
manufacturer’s test certificates.
k)
A declaration of its chemical
composition in sufficient
detail for its carbon
equivalent to be calculated
Determined by non-destructive and
destructive tests.
Table 3.1 – Material
properties to
be declared for
reclaimed steelwork
according to
BS EN 1090-2
10
CE MARKING OF RECLAIMED
STRUCTURAL STEELWORK
the same form, original function, size and details, from the same building and being
less than 20 tonnes in total. More details on member groups are given in Section 6.1.
Destructive tests are used to establish the yield strength and ultimate strength of one
or more representative samples from the group (see Section 7.2) to conrm the correct
material grade for the group has been identied.
3.5.2 Elongation
The use of reclaimed steelwork is limited to applications where signicant ductility
is not required, i.e. plastic global analysis is not recommended, and is limited to the
reuse of relatively ‘modern’ steel (see Section 5.3). The demands on elongation are
therefore limited, and likely to be met by the reclaimed steelwork.
Elongation must be specied according to BS EN 1090-2 clause 5.1 and determined by
destructive testing.
3.5.3 Tolerances on dimensions and shape
Reclaimed elements must be checked against geometric tolerances. Elements within
tolerance are acceptable and satisfy the assumptions made in the design standard.
Table 3.2 lists the standards to be used when assessing dimensions and tolerances.
Products Dimensions Tolerances
I and H sections EN 10365[4] EN 10034[5]
Hot-rolled taper flange I
sections
EN 10365 EN 10024[6]
Channels EN 10365 EN 10279[7]
Equal and unequal leg angles EN 10056-1[8] EN 10056-2[9]
T Sections EN 10055[10] EN 10055
Plates, flats, wide flats - EN 10029[11]
EN 10051[12]
Bars and rods
EN 10017[13], EN 10058[14],
EN 10059[15], EN 10060[16],
EN 10061[17]
EN 10017, EN 10058,
EN 10059, EN 10060,
EN 10061
Hot finished hollow sections EN 10210-2 [18] EN 10210-2
Cold formed hollow sections EN 10219-2 [19] EN 10219-2
Fabricated profiles and
member bow imperfections
EN 1090-2 EN 1090-2
3.5.4 Through thickness requirements
Through thickness properties are generally not required for reclaimed sections, such
as beams or columns. Some joint details may require the steel plate to have through
thickness properties. If through thickness properties are required, reclaimed plate
must be tested as specied in BS EN 1993-1-10[20].
Table 3.2 –
Dimensions and
tolerances for
structural steelwork
11
3.5.5 Impact strength or toughness
A certain impact strength or toughness (commonly known as the Charpy value) might
be required for a specic project, such as for thick, highly stressed steelwork exposed
to low temperatures. However, for internal steelwork which is not subjected to fatigue, a
conservative assumption about the material toughness is appropriate.
If material toughness must be determined, destructive tests are required in accordance
with the requirements of the relevant standard, e.g. Clause 10.2.2 of BS EN 10025-1.
3.5.6 Heat treatment delivery condition of hollow sections
Hollow sections are cold formed to BS EN 10219[21] or hot nished to BS EN 10210[22].
Conservatively, it is recommended that all reclaimed hollow sections are assumed to
be cold formed according to EN 10219.
3.5.7 Declaration of chemical composition
Chemical composition is important to establish the durability and particularly
the weldability of the reclaimed structural steel. The stockholder must provide a
declaration of chemical composition, based on non-destructive and destructive tests.
The chemical composition declaration must provide measures of certain chemical
elements according to the relevant standard. The intent of this declaration is to
enable the carbon equivalent value (CEV) to be calculated, which is a key measure
of weldability.
12
13
This section summarises the recommendations for structural design and verication of
reclaimed structural steel members.
4.1 Structure scope
This protocol has been prepared on the basis that reclaimed steel can be used
in Consequence class 1, 2 or 3 structures (see Table B1 of BS EN 1990). Use of
reclaimed steelwork in Consequence class 3 structures places additional requirements
on the testing regime to determine material characteristics.
Reclaimed steel should not be used in structures subject to fatigue, or in plastically
analysed structures which rely on the formation of plastic hinges. Similarly, the use of
reclaimed steel in structures subject to seismic loading is excluded, unless the steel
plays no part in resisting the seismic action, for example as a pin-ended oor beam.
4.2 Ductility and residual strains
Elongation of steel is a mandatory declaration according to clause 5.1 of BS EN 1090-2
and must be determined by a destructive test.
Plastic global analysis is not recommended when reclaimed steel is reused. The
limitations on the ratio between the ultimate strength (fu) and the yield strength (fy) as
well as the minimum elongation appropriate for elastic global analysis are given in the
National Annex to EN 1993-1-1.
Careful visual inspection of every reclaimed member, and assessment against the
tolerances referenced in Section 3.5.3 should ensure that the element has not
undergone plastic deformations and therefore the residual strains, and reserves of
ductility, are no different to that of ‘new’ steel.
4.3 Global analysis
Designers should not undertake plastic global analysis, as this demands a high level of
ductility. Although elongation of steel will be demonstrated by test, it is still considered
prudent to restrict practice to elastic global analysis.
DESIGN
RECOMMENDATIONS
14
DESIGN RECOMMENDATIONS
4.4 Cross sectional resistance
Reclaimed steel is assumed to be sufciently ductile to permit the use of a plastic
cross-sectional resistance, for example, in bending or shear. The design resistances
presented in BS EN 1993-1-1 should be used.
For cross sectional resistance, the National Annex recommended values for γM0 and
γM2 should be used for steelwork erected after 1970 that complies with this testing
protocol. Further guidance and background is provided in Appendix A.
4.5 Buckling resistance
For reclaimed steel, a modied value of γM1,mod=1.15 γM1 is recommended, which
reects the increased uncertainty when using reclaimed steel.
Justication for this recommendation is given in Appendix A.
For ‘new’ steel, for example from a cancelled project - not erected, which has
appropriate documentation, the current value of γM1 from the National Annex to
EN 1993-1-1 should be used. The UK National Annex[23] recommends γM1=1.00.
4.6 Steel toughness and sub-grade
It is assumed that all steel used in construction since 1970 has a minimum Charpy
V-notch impact value of 27 J at 20°C, which corresponds to the JR subgrade
according to BS EN 10025. The reclaimed steel sub-grade may be assumed to be JR
without testing.
Clause 5.1 of BS EN 1090-2 states that a declaration of steel subgrade is not
mandatory. Where the declaration of the reclaimed steel subgrade is required,
for example, for external steelwork exposed to low temperatures, the steel
subgrade needs to be determined by tests. Tests and relevant documentation is a
stockholder responsibility.
Since the scope for the reuse of reclaimed steel is limited to structures where fatigue
is not a design consideration (Section 4.1), the limiting thickness values presented
in SCI Publication P419[24] are recommended for use in the UK. SCI P419 adopts the
procedures of the Eurocode, but reduces the calculated crack growth for applications
where fatigue is not a design consideration.
For internal steelwork used in the most onerous circumstances (“Combination 10”):
S275 JR – the limiting thickness is 77.5 mm
S355 JR – the limiting thickness is 35 mm
15
For external steelwork used in the most onerous circumstances (“Combination 10”):
S275 JR – the limiting thickness is 32.5 mm
S355 JR – the limiting thickness is 16.5 mm
“Combination 10” refers to the column identication provided in Table 2 and Table 3 of
PD 6695-1-10[25] and Table 5.1 and Table 5.2 of SCI P419.
The preceding values fully respect the requirements of the UK National Annex. For less
severe details, and lower stress levels, i.e. a lower combination, the limiting thickness
increases and SCI P419 should be consulted for a less onerous value.
4.7 Revised thickness limits for use outside the UK
The thickness limits given in SCI P419 and summarised in Section 4.6 are only
appropriate for the UK, as they include all the provisions of the UK National Annex to
BS EN 1993-1-10.
Table 4.1 follows the same format as Table 2.1 of EN 1993-1-10, but adopts the
reduced crack growth assumed in SCI publication P419. The values in Table 4.1 can
be used in countries other than the UK, when fatigue is not a design consideration,
subject to any requirements of the specic National Annex of the country
of construction.
4.8 Connection design
This protocol anticipates that the primary use of reclaimed steelwork will be as plain
members, i.e. with existing connections removed or redundant.
If new connections to the reclaimed steelwork require welding of some components,
the carbon equivalent value (CEV) will be required in order to develop appropriate
welding procedures. The chemical composition of the steelwork is a mandatory
declaration according to clause 5.1 of BS EN 1090-2. The declared CEV should be
the maximum value determined from the non-destructive and destructive tests (see
Appendix E). A high CEV will generally not be detrimental unless the joint has a high
combined thickness (the sum of the thickness of all the elements meeting at the joint).
If connections are to be re-used, previous research[26] indicates that it may be assumed
that the strength of the weld material is at least equal to the base steelwork . This
advice does not cover workmanship – it is recommended that any existing welds that
are to be reused are carefully inspected and tested.
16
DESIGN RECOMMENDATIONS
Table 4.1 – Limiting
thickness values
when fatigue
is not a design
consideration
Reference temperature, TEd (°C)
Charpy energy
CVN
10 0 -10 -20 -30 -40 -50 10 0 -10 -20 -30 -40 -50 10 0 -10 -20 -30 -40 -50
Steel
grade
Sub
Grade at T (°C) Jmin 𝜎Ed = 0.75 fy(t)𝜎Ed = 0.5 fy(t)𝜎Ed = 0.25 fy(t)
S235
JR 20 27 200 200 200 195 125 87 63 200 200 200 200 200 200 161 200 200 200 200 200 200 200
J0 0 27 200 200 200 200 200 195 125 200 200 200 200 200 200 200 200 200 200 200 200 200 200
J2 -20 27 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200
S275
JR 20 27 200 200 200 133 91 64 47 200 200 200 200 200 170 121 200 200 200 200 200 200 200
J0 0 27 200 200 200 200 200 133 91 200 200 200 200 200 200 200 200 200 200 200 200 200 200
J2 -20 27 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200
M,N -20 40 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200
ML, NL -50 27 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200
S355
JR 20 27 200 177 114 77 54 40 30 200 200 200 200 147 104 76 200 200 200 200 200 200 200
J0 0 27 200 200 200 177 114 77 54 200 200 200 200 200 200 147 200 200 200 200 200 200 200
J2 -20 27 200 200 200 200 200 177 114 200 200 200 200 200 200 200 200 200 200 200 200 200 200
K2,M, N -20 40 200 200 200 200 200 200 177 200 200 200 200 200 200 200 200 200 200 200 200 200 200
ML, NL -50 27 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200
S460
Q -20 30 200 200 200 200 147 96 65 200 200 200 200 200 200 187 200 200 200 200 200 200 200
M, N -20 40 200 200 200 200 200 147 96 200 200 200 200 200 200 200 200 200 200 200 200 200 200
QL -40 30 200 200 200 200 200 200 147 200 200 200 200 200 200 200 200 200 200 200 200 200 200
ML, NL -50 27 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200
QL1 -60 30 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200
S690
Q 0 40 200 137 89 58 40 28 20 200 200 200 174 115 78 55 200 200 200 200 200 200 200
Q -20 30 200 200 137 89 58 40 28 200 200 200 200 174 115 78 200 200 200 200 200 200 200
QL -20 40 200 200 200 137 89 58 40 200 200 200 200 200 174 115 200 200 200 200 200 200 200
QL -40 30 200 200 200 200 137 89 58 200 200 200 200 200 200 174 200 200 200 200 200 200 200
QL1 -40 40 200 200 200 200 200 137 89 200 200 200 200 200 200 200 200 200 200 200 200 200 200
QL1 -60 30 200 200 200 200 200 200 137 200 200 200 200 200 200 200 200 200 200 200 200 200 200
17
18
19
5.1 Introduction
All structural steel reclaimed for reuse, is to be inspected and tested. Central to
the testing regime is the grouping of fundamentally identical members into groups,
whereby one (or more) members are assumed to be representative of the entire group,
thus moderating the requirements for testing. The data to be recorded, initially and
after subsequent testing, is set out in Appendix B.
Without traceability of each component, the value of the reclaimed material will
be compromised. It is therefore important for material stockists to maintain full
traceability of the reclaimed steelwork, including the grouping and labelling of
members.
5.2 Preliminary assessment
Assessment of the reclaimed steelwork begins before the existing structure is
deconstructed, with the collection of relevant data. Section 5.4 describes the initial
data to be collected, and Section 7 the general principles of the testing regime.
In addition to the assessment of the steel elements, the preliminary assessment
should consider the method of deconstruction and a safe method of work.
5.3 Admissibility of reclaimed steelwork
The following scope for reclaimed steel is necessary to complement recommendations
in this protocol:
Steelwork no older than 1970;
No built-up members (unless welds are tested);
No spliced members (the individual lengths of a member with a bolted or welded
splice can be disassembled/cut and reclaimed; otherwise, welds need to be tested);
ASSESSMENT
OF RECLAIMED
STEELWORK FOR REUSE
20
ASSESSMENT OF RECLAIMED
STEELWORK FOR REUSE
No signicant section loss due to corrosion (loss exceeding 5% of the element
thickness is considered signicant);
No signs of re exposure;
No evidence of plasticity observed in the steel surface or corrosion protection;
Members must meet the geometric tolerances of BS EN 1090-2 (straightening can
be performed if tolerances are not met).
The limitation to steel produced after 1970 relates to the material properties assumed
by modern design standards. Steel from 1970 was considered as part of the Eurocode
programme and the development of product and design standards. It is therefore
assumed that steel produced after 1970 meets the material properties assumed in
product standards such as BS EN 10025 and BS EN 10219.
5.4 Assessment and initial data collection
Before deconstruction and reclamation of the steelwork, data about the existing
structure is to be collected, and visible steelwork assessed. The following data should
be recorded from the existing structure and steelwork:
A description of the structure and its use. This should include a description of how
the building is stabilised;
The age of the structure, which may be from records, or local information;
A preliminary listing of the steel members;
A preliminary inspection of the members for damage, obvious repairs, signicant
corrosion;
Any evidence of plasticity.
5.5 Inspection requirements undertaken by stock
holder
After reclamation, the responsibility of the holder of the stock is to inspect every
member and maintain records that include:
Dimensions (cross section and length);
Straightness (assessed against the tolerances);
Any signicant loss of section;
Signs of damage, or plastic strain.
21
22
23
The organisation holding the reclaimed steel stock has important responsibilities
involving the examination and testing of the steelwork, including maintaining the
grouping of reclaimed members, keeping of comprehensive records and formal
declarations of material properties when the reclaimed steelwork is distributed into the
supply chain.
A listing of the necessary records is provided in Appendix B.
6.1 Member grouping
Reclaimed steel members are to be considered as a group, provided they are from the
same original source structure and meet the following requirements:
Structural steel erected after 1970;
Of the same serial size;
Same structural function, e.g. rafters, oor beams, columns, bracings, etc.;
Identical detailing (length, connections, etc.).
If steelwork originally manufactured to an alternative specication, e.g. an American
product standard rather than a BS EN, is to be placed on the market (see Section
2.3), material manufactured to different product standards should not be mixed within
a group – the source and manufacturing standard of all material in a group should
be consistent.
A group should comprise a maximum of 20 tonnes. Several groups of 20 tonnes will
be required if large numbers of the same member are reclaimed. Grouping in this way
allows certain material characteristics to be established for the group by testing one or
more representative members from the group.
In this protocol, the concept of a ‘group’ has special signicance, as outlined above.
In product standards such as BS EN 10025-2, a similar term is ‘test unit’, indicating
a collection of steel products of a specied total maximum weight of the same form,
grade and quality and delivery condition. A ‘test unit’ can contain products of various
thickness, whereas in this protocol, a ‘group’ is limited to members of the same serial
size. In product standards, tests are specied to be undertaken from samples in
RESPONSIBILITIES OF
THE HOLDER OF STOCK
24
RESPONSIBILITIES OF THE
HOLDER OF STOCK
the test unit; in this protocol, tests are specied to be undertaken from samples in
the group.
6.2 Records
Records must be maintained for each group of reclaimed structural steel members,
including:
Details of the source structure;
Unique identication of the group to which reclaimed members belong;
Unique identication of every single element within the group;
Records of physical inspection, including tolerances on cross-section and bow
imperfections;
Hardness test result and consequent material grade for each individual member;
Destructive tensile tests results for yield strength, ultimate strength and elongation;
Non-destructive and destructive tests to determine the CEV;
Any assumed material properties such as sub-grade or heat treatment
delivery conditions.
6.3 Declarations
When reclaimed steelwork is distributed into the supply chain, it must be accompanied
by a formal declaration, following the requirements of BS EN 1090-2.
The declaration must make clear which properties have been assumed, and which
have been determined by test, noting that the determination is by group and in
accordance with the guidance in this protocol.
25
26
27
7.1 Introduction
This section describes the tests to be undertaken by the holder of the reclaimed
steelwork. It is required that the company holding the stock maintains appropriate
records of test results, and makes appropriate formal declarations of the test results
when the steel is sold.
A comprehensive listing of the data to be recorded is given in Appendix B.
Details of the testing requirements are presented in Appendices C to F, referenced in
Table 7.1.
Products Appendix
Yield strength, ultimate strength and elongation C
Impact toughness (if required) D
Product analysis to determine CEV E
Section dimensions and member straightness F
7.2 Non-statistical and statistical testing
The recommendations of this protocol require 100% non-destructive testing of the
reclaimed structural members in combination with non-statistical or statistical
destructive testing.
The non-destructive testing of all reclaimed members establishes that a group of
members (see Section 6.1) can be represented by destructive test results from one or
more representative members from the group.
Non-statistical testing requires just one destructive test, taken from a member in each
group, to conrm the results obtained from the non-destructive tests. Non-statistical
testing is recommended for Consequence class 1 or 2 structures. Non-statistical
testing is equivalent to the requirements for ‘new’ steel specied in the product
standard.
Statistical testing requires more destructive testing to assess material characteristics
in accordance with BS EN 1990. Statistical testing is recommended for reclaimed steel
TEST PROGRAMME
Table 7.1 – Testing
requirements
28
TEST PROGRAMME
to be used in Consequence class 3 buildings, or when the provenance or quality of the
original source material is considered to be unreliable. Statistical testing exceeds the
requirements for ‘new’ steel specied in the product standard.
Table 7.2 relates the recommended testing approach for yield strength, ultimate
strength, elongation and chemical composition to Consequence class.
Consequence
class NDT Minimum
number of DT Acceptance approach
CC1 All members to
be subject to
non-destructive
tests to establish
yield strength,
ultimate strength
and CEV
1 Non-statistical (maximum
value of CEV)
CC2 1 Non-statistical (maximum
value of CEV)
CC3
3 Statistical for yield strength,
ultimate strength and
elongation (maximum
value of CEV)
Table 7.2 – Testing
approach related to
Consequence class
29
30
31
8.1 General comments
All fabricated steelwork should conform to the requirements of BS EN 1090-2.
8.2 Existing coatings on reclaimed steelwork
In most situations, it is envisaged that any existing coating is to be entirely removed
prior to fabrication. The reuse of steelwork with its original protection is likely to
be limited to situations when the entire structure is dismantled, relocated and
reconstructed, largely in its original form.
If the reuse of steelwork with corrosion protection is considered, the following issues
should be considered:
Existing corrosion protection systems are likely to need remedial work after
dismantling the structure, and after any fabrication activity;
Existing corrosion protection systems might contain hazardous substances,
prohibited under current legislation;
Although corrosion protection systems for internal steelwork might be more durable
than originally anticipated, the original level of protection is likely to have diminished
and to be less than recommended under current guidance.
Fire protection coatings are highly sensitive to humidity and are uniquely linked to
the original member. For both of these reasons, no reliance should be placed on any
original re protection coatings.
8.3 Bolt holes and welds in reclaimed steel
The reuse of members with holes for structural bolts is permitted if all geometric and
design requirements according to BS EN 1993-1-1 and BS EN 1993-1-8[27] are fullled.
If bolt holes are located within the critical cross-section and reduce the cross-section
by more than 15%, the net cross-sectional properties should be used in member
verication.
FABRICATION ISSUES
32
FABRICATION ISSUES
As a detailing recommendation for reclaimed steel with existing holes, new connections
within 100 mm of existing holes should be avoided.
If present, larger holes, e.g. for passage of services, must be assessed on an individual
basis during member verication.
In general, it is recommended that redundant welded ttings, e.g. stiffeners or cleats,
need not be removed.
8.4 Existing connections
Special care is needed if existing connections are to be re-used. In particular, any
welding should be subject to careful inspection and test.
The steel grade of connecting plates and other ttings should be assessed by non-
destructive tests following the recommendations in Appendix C.3. The steel elongation
is assumed to be at least equal to that obtained for the main structural members.
As a general recommendation, at least the same amount of weld testing required
by BS EN 1090-2 (Table 24) should be applied to reclaimed steel elements. Visual
inspection of 100% of the welds is recommended.
33
34
35
[1] BS EN 1090-1:2009+A1:2011. Execution of steel structures and aluminium structures.
Requirements for conformity assessment of structural components, BSI.
[2] BS EN 1993-1-1:2005+A1:2014. Eurocode 3: Design of steel structures, Part 1-1: General
rules and rules for buildings, BSI.
[3] BS EN 1090-2:2018. Execution of steel structures and aluminium structures Technical
requirements for steel structures, BSI.
[4] BS EN 10365:2017. Hot rolled steel channels, I and H sections. Dimensions and masses, BSI.
[5] BS EN 10034:1993. Structural steel I and H sections. Tolerances on shape and dimensions,
BSI.
[6] BS EN 10024:1995. Hot rolled taper ange I sections. Tolerances on shape and dimensions,
BSI.
[7] BS EN 10279:2000. Hot rolled steel channels. Tolerances on shape, dimension and mass,
BSI.
[8] BS EN 10056-1:2017. Structural steel equal and unequal leg angles. Dimensions, BSI.
[9] BS EN 10056-2:1993. Specication for structural steel equal and unequal angles. Tolerances
on shape and dimensions, BSI.
[10] BS EN 10055:1996. Hot rolled steel equal ange tees with radiused root and toes.
Dimensions and tolerances on shape and dimensions, BSI.
[11] BS EN 10029:2010. Hot-rolled steel plates 3 mm thick or above. Tolerances on dimensions
and shape, BSI.
[12] BS EN 10051:2010. Continuously hot-rolled strip and plate/sheet cut from wide strip of non-
alloy and alloy steels. Tolerances on dimensions and shape, BSI.
[13] BS EN 10017:2004. Steel rod for drawing and/or cold rolling. Dimensions and tolerances, BSI.
[14] BS EN 10058:2018. Hot rolled at steel bars and steel wide ats for general purposes.
Dimensions and tolerances on shape and dimensions, BSI.
[15] BS EN 10059:2003. Hot rolled square steel bars for general purposes. Dimensions and
tolerances on shape and dimensions, BSI.
REFERENCES
36
REFERENCES
[16] BS EN 10060:2003. Hot rolled round steel bars for general purposes. Dimensions and
tolerances on shape and dimensions, BSI.
[17] BS EN 10061:2003. Hot rolled hexagon steel bars for general purposes. Dimensions and
tolerances on shape and dimensions, BSI.
[18] BS EN 10210-2:2019. Hot nished steel structural hollow sections. Tolerances, dimensions
and sectional properties, BSI.
[19] BS EN 10219-2:2019. Cold formed welded steel structural hollow sections. Tolerances,
dimensions and sectional properties, BSI.
[20] BS EN 1993-1-10:2005. Eurocode 3. Design of steel structures. Material toughness and
through-thickness properties, BSI.
[21] BS EN 10219-1:2006. Cold formed welded structural hollow sections of non-alloy and ne
grain steels. Technical delivery requirements, BSI.
[22] BS EN 10210-1:2006. Hot nished structural hollow sections of non-alloy and ne grain steels.
Technical delivery requirements, BSI.
[23] NA+A1:2014 to BS EN 1993-1-1:2005+A1:14 UK National Annex to Eurocode 3. Design of
steel structures. General rules and rules for buildings, BSI, 2014.
[24] SCI P419 Brittle fracture selection of steel sub-grade to BS EN 1993-1-10, SCI, 2018.
[25] PD 6695-1-10 Recommendations for the design of structures to BS EN 1993-1-0, BSI, 2009.
[26] SIA 269/3:2011. Existing structures – Steel structures, SIA Zurich.
[27] BS EN 1993-1-8:2005. Eurocode 3. Design of steel structures. Design of joints, BSI.
[28] Standardisation of safety assessment procedures across brittle to ductile failure modes
(SAFEBRICTILE) RFCS project RFSR-CT-2013-00023.
[29] An Evaluation of Mechanical Properties with the Hardness of Building Steel Structural
Members for Reuse by NDT Masanori Fujita and Keiichi Kuki; Metals 2016.
[30] BS EN ISO 18265:2013 Metallic materials. Conversion of hardness values, BSI.
37
CREDITS
18 Schiphol bus station
vi Photo courtesy of North Lincs
Structures
22 Fokker distribution centre,
Schiphol airport
26 NTS warehouse, Thirsk Photo
courtesy of Cleveland Steel
and Tubes
iv Cleveland Steel and Tubes
stockyard, Thirsk Photo
courtesy of Cleveland Steel
and Tubes
38
39
A.1 ENV 1993-1-1 background
The data used to develop the Eurocode material factors reviewed material test results
taken between 1969 and 1989. In ENV 1993-1-1, a value of γM1= 1.10 was initially
proposed, with values of γM0= 1.00 for major axis bending and γM0= 1.10 for minor
axis bending. The introduction of a different approach for lateral torsional buckling
curves allowed the reduction from γM1= 1.10 to γM1= 1.00 . Later, it was proposed that
by taking into account strain hardening, it was possible to justify the use of γM0= 1.00
for both major and minor axis bending. These are the material factors currently
recommended by the Eurocode.
A.2 The value of γM1
The buckling resistance of a member is based on the design strength, the cross
sectional properties and a choice of buckling curve. The choice of buckling curve is
associated with an initial imperfection which allows for physical imperfections, residual
stresses, cross sectional variations, etc.
The procedures recommended in this protocol are intended to ensure that the
assumed design strength is conservative. Members must meet the dimensional and
straightness tolerances in BS EN 1090-2, meaning that the choice of buckling curve is
the same for both new and reclaimed steel. Since the reclaimed steel is limited to steel
used in construction after 1970, it is assumed that the residual stresses will not be
signicantly different from the stresses present when the design models in
ENV 1993-1-1 were developed and calibrated.
Nevertheless, some degree of uncertainty is inevitably associated with the use of
reclaimed steelwork. In addition to member straightness, other imperfections in the
cross sections or torsional imperfections can contribute to a reduced resistance due
to the increase of second order effects. Even if all geometric tolerances are satised,
a degree of uncertainty will remain as the assessment processes are likely to be
less reliable than those undertaken for the continuous production of new steel. A
conservative value of γM1 is suggested in this protocol to address this uncertainty.
APPENDIX A
DESIGN
RECOMMENDATIONS
40
APPENDIX A
The recommended value for γM1,mod is based on increasing the target reliability index
(β) from 3.8 to 4.3 for a 50-year reference period (see Table B2 of BS EN 1990). The
recommendation for γM1,mod (for all steel grades) is based on principles expressed in
BS EN 1990 with a conservative assumption for the partial factor associated with the
uncertainty of the resistance model (γRd).
The recommended value of γM1,mod is given by:
γM1,mod= KγM1 x γM1, where KγM1= 1.15.
For the UK and based on the recommended value of γM1 in BS EN 1993-1-1,
γM1,mod= 1.15.
Adoption of γM1,mod will only have an impact on the design of members where buckling
is the critical verication. For members subject to buckling, it might be necessary to
introduce additional intermediate restraints if the original buckling resistance is to be
maintained in the redesigned reclaimed steel member.
A.3 The values of γM0 and γM2
As ENV 1993-1-1 was based on tests performed on steel produced as early as 1969,
it is reasonable to assume that there are no concerns with cross section resistance for
reclaimed steel from the subsequent decades.
No change in the recommended value for γM0 or γM2 is therefore proposed for
verication of cross sections in accordance with BS EN 1993-1-1. The cross sectional
resistance depends on dimensional characteristics and material strength, which have
both been veried for every reclaimed member.
A.4 Consequence class 1 structures
The recommended value of KγM1= 1.15 should be used for Consequence class 1
structures such as agricultural buildings. It is recommended that the factor KFI= 0.90
(see BS EN 1990 Table B3) is applied to all partial factors if designing a Consequence
class 1 structure.
A.5 Consequence class 2 structures
The recommended value of KγM1= 1.15 should be used for Consequence class 2
structures.
A.6 Consequence class 3 structures
41
The recommended value of KγM1= 1.15 should be used for Consequence class 3
structures.
Although BS EN 1990 allows designers to apply the factor KFI = 1.10 to all partial
factors (see EN 1990 Table B3) when designing a Consequence class 3 structure,
normal practice in the UK is to increase design supervision and inspection during
execution (Tables B4 and B5 of BS EN 1990) as an alternative to the KFI factor.
42
43
B.1 Data records
The following data should be recorded and associated with each structural member:
Building information
Building age, location
Form of construction, e.g. braced, continuous, etc.
Any related information, such as drawings, modications, records.
Individual members
Section size,
Length,
Group (see Section 6.1),
Member individual identication,
Tolerance check (section dimensions and bow imperfections)
Comments, e.g. stiffeners or fabricated features,
Coating;
Coating type (and thickness if determined),
Condition of coating,
Material properties;
Material properties shall be determined by non-destructive tests and/or by destructive
tests. The test results, together with any derived values, shall be recorded for the
following properties:
Yield and ultimate strengths (non-destructive and destructive tests),
Elongation (destructive tests),
Chemical composition (non-destructive and destructive tests),
Carbon Equivalent Value (CEV),
Impact toughness (by destructive tests, if required).
APPENDIX B
DATA RECORDS AND
INFORMATION
44
APPENDIX B
Conservative assumptions may be made to dene:
Impact toughness (assumed, if not tested)
Heat treatment.
The product standard used to infer relevant material properties shall be stated, e.g.
BS EN 10025 or BS EN 10219.
Stockholder records
Stockholder details (name and other relevant information);
Internal report/documentation number (based on stockholder records);
Other quality records (testing laboratories, etc.).
45
46
47
Within this protocol, material strength and elongation are assessed by both destructive
and non-destructive tests. In the following section guidance is provided on both types
of testing.
C.1 Measured strength and assumed steel grade
The results of non-destructive and destructive tests should be compared with the
values presented in Table C.1 in order to determine the steel grade. The values in
Table C.1 have been developed from reference[28].
Yield strength
(N/mm2)
Ultimate strength
(N/mm2)
Steel grade Minimum Mean Minimum Mean fy/ fu
mean Standard
S235 267 293 397 432 1.47 EN 10025-2;
EN 10219
S275 313 343 452 492 1.43 EN 10025-2;
EN 10219
S355 391 426 505 540 1.26 EN 10025-2;
EN 10219
S460 490 529 560 595 1.12 EN 10025-3/4;
EN 10219
The values in Table C.1 are appropriate for steel with thicknesses between 3 mm and
60 mm.
Every element within a group must comply with the minimum yield strength from
Table C.1 in order for the associated grade to be assumed.
APPENDIX C
STRENGTH AND
ELONGATION
Table C.1 – Steel
grade identication
from test results
48
APPENDIX C
C.2 Non-destructive hardness tests
Every reclaimed member is to be subjected to a non-destructive hardness test in
order to establish a value for the yield strength and the ultimate strength of the
steel. A relationship exists between measured hardness and steel strength which
is considered sufciently accurate to establish the material grade. The relationship
between measured hardness and material strength depends on the type of hardness
test performed.
Hardness testing should be completed on the anges of reclaimed elements, at
locations of lower stress in service. For simply supported beams, locations near the
end of the element are recommended. Any surface treatment must be removed from
the area to be tested.
The material hardness should be taken as the mean of three measurements in the
same location.
Results from each member in a group should be assessed in accordance with
BS EN 1990 to determine the representative value for the whole group. Once the
hardness value for the group has been established, the yield strength and ultimate
strength should be calculated and compared with Table C.1 to establish the
steel grade.
C.2.1 Assessment of hardness test results
The hardness of an individual member should be taken as the average of three
measurements. If this average value for an individual member differs by more than
10% from the average value for the group of members, the inconsistent member
should be removed from the group.
The characteristic value of hardness Hv of the entire group should be determined
using Table D1 from BS EN 1990, assuming “Vx unknown” and calculated using the
following expression:
Hv = mknVx
where:
Hv is the characteristic value of hardness for the group
m is the sample mean value (mean hardness of the members within the group)
Vx is the standard deviation of the results
kn is taken from Table D1 of BS EN 1990 for “Vx unknown”, presented as Table C.2
49
Number of
members in
the group (n)
1 2 3 4 5 6 8 10 20 30
Vx unknown - - 3.37 2.63 2.33 2.18 2.00 1.92 1.76 1.73 1.64
C.2.2 Correlation between hardness and material strength
If the Vickers hardness is tested, the following relationship between hardness and
strength can be used to estimate the material properties[29]:
fy = 2.70 Hv – 71
fu = 2.50 Hv + 100
where:
Hv is the Vickers hardness value for the group, determined in accordance with C.2.1
fy is the yield strength
fu is the ultimate strength
BS EN ISO 18265[30] can also be used to estimate ultimate strength based on hardness
values.
C.2.3 Calculation example
In this example, 20 steel members have been identied as a group. Each member
was subject to a non-destructive hardness test. Three measurements were taken
from each member and the mean result calculated. The mean of the 20 results was
calculated as 169.5. The standard deviation was calculated as 5.06.
As 20 members have been tested, n = 20 and kn = 1.76
For the group, Hv = 169.5 – 1.76 × 5.06 = 160.6
If Hv = 160.6, then according to Section C.2.2:
fy = 2.7 × 160.6 – 71 = 362 N/mm2
and
fu = 2.5 × 160.6 + 100 = 502 N/mm2
According to Table C.1 the steel is identied as S275, as the yield strength is greater
than 313 kN/mm2 and the ultimate strength is greater than 452 kN/mm2.
Table C.2 – Values
of kn for the 5%
characteristic
value (BS EN 1990
Table D1).
50
APPENDIX C
C.3 Destructive tensile tests: non-statistical and
statistical testing regimes
C.3.1 General guidance for destructive testing
The location of samples for destructive tests should be selected according to the
recommendations of the product standard. Annex A of BS EN 10025-1 provides
guidance for hot rolled members and plates. Annex C of BS EN 10219-1 provides
guidance for hollow sections.
Destructive tensile tests are used to determine the following properties of the steel:
Yield strength,
Ultimate strength,
Yield to ultimate ratio,
Elongation at failure.
The declared yield strength, ultimate strength and elongation should be based on
the results of the destructive tests, not on the non-destructive tests. The declared
yield strength and ultimate strength should be the strengths given in the appropriate
product standard for the determined steel grade, which is identied using results of the
destructive tests, not on the non-destructive tests
C.3.2 Non-statistical testing
In addition to the 100% non-destructive testing of every member, a single destructive
test (taken from any member in the group) is required to conrm the assessment
described in Section C.2. A single test has no statistical value, and is therefore
described as ‘non-statistical’.
Non-statistical destructive testing (i.e. one single destructive test from a group) is
recommended for steel to be used in Consequence class 1 or Consequence class
2 structures.
C.3.3 Statistical testing
If reclaimed steel is to be used in Consequence class 3 structures, a greater degree of
reliability is required. In addition to the 100% non-destructive testing of every member,
the mechanical properties of the steel members should be determined by increasing
the number of destructive tests, and completing an assessment in accordance with
BS EN 1990.
A minimum of three destructive tests are required, taken from members within a group.
Increasing the number of tests will improve the precision of the calculated values and
will generally result in higher values.
51
The characteristic value of yield strength and ultimate strength of the entire group
should be determined using Table D1 from BS EN 1990, assuming “Vx known” and
calculated using the following expression:
Xd = mknVx
where:
Xd is the characteristic value of interest (yield strength, or ultimate strength),
m is the sample mean value;
Vx is the standard deviation;
kn is taken from Table D1 of BS EN 1990 for “Vx known”, presented as Table C.3
Number of
tests 1 2 3 4 5 6 8 10 20 30
V
x known - - 1.89 1.83 1.80 1.77 1.74 1.72 1.68 1.67 1.64
The use of “Vx known” is justied because the coefcient of variation for both yield
strength and ultimate strength is known.
If statistical testing is completed, the calculated values from the destructive tests
should be used to determine the steel grade from Table C.1.
Table C.3 – Values
of kn for the 5%
characteristic
value (BS EN 1990
Table D1)
52
53
D.1 Destructive tests
Unless destructive tests are conducted, it should be assumed that the steel is
subgrade JR. There may be economic benets in completing destructive tests
to demonstrate that reclaimed steel is of a tougher sub-grade, particularly on
thicker sections.
If required, destructive tests should be used to establish the steel sub-grade of
members within a group, based on the testing of one representative member. In
accordance with BS EN 10025-1, six samples are required for testing purposes, taken
from locations identied in Annex A of BS EN 10025-1.
APPENDIX D
IMPACT TOUGHNESS
54
55
E.1 Introduction
The chemical composition of reclaimed steel should be determined so that the Carbon
Equivalent Value (CEV) can be calculated using the expression given in BS EN 10025-1
Section 7.2.3 or BS EN 10219-1 Section 6.6.1.
The chemical composition should be assessed using non-destructive and destructive
techniques. The CEV for the group should be taken as the maximum CEV from any test,
including both the non-destructive test results and the destructive test results.
The chemical composition of each individual member should be tested and recorded. If
the measured carbon or manganese content for an individual member differs by more
than 10% from the average value for the group, the inconsistent member should be
removed from the group.
The anticipated chemical composition of a specic steel can be found in Section 6.6.1
of the relevant part of BS EN 10025 and BS EN 10219.
E.2 Non-destructive tests to establish chemical
composition
Optical emission spectroscopy can be used to determine the chemical composition
of a steel member. Although this technique is considered to be a non-destructive test
method, a small burr is left on the surface of the steel.
E.3 Destructive tests to establish chemical
composition
The chemical composition of the steel can be established by analysing swarf from a
drilled cavity. The member should be drilled in a low stress location.
For Consequence class 1 and Consequence class 2 structures, destructive tests on
one representative member should be used to establish the chemical composition for
all members in the group.
For Consequence class 3 structures, where a minimum of three destructive tests are
recommended (see Table 7.2), no statistical analysis should be undertaken.
APPENDIX E
CHEMICAL
COMPOSITION
56
57
F.1 Cross section dimensions
The cross sectional dimensions (depth, breadth, ange thickness, web thickness, wall
thickness, etc.) must be measured for all members. A declaration of the measured
dimensions must be provided by the stockholder.
If the section dimensions fall outside the permitted deviations according to the product
standard (see Table 3.2), the measured dimensions should be used to determine the
cross sectional properties.
F.2 Bow imperfections (lack of straightness)
The straightness of every member, in both axes, should be measured and compared
with the permitted deviations in BS EN 1090-2. Members falling outside the permitted
deviations should be straightened as part of the fabrication process.
APPENDIX F
GEOMETRIC
TOLERANCES
59
60
61
62
The environmental advantages of re-using reclaimed structural steel are considerable, compared
to the common practice of recycling.
The publication proposes a system of investigation and testing to establish material characteristics,
with advice for designers completing member verications of reclaimed steelwork. It places
important responsibilities on the holder of reclaimed steelwork including identication,
assessment, control procedures and declarations of conformity.
The protocol is founded on the principle that given appropriate determination of material
characteristics and tolerances, (re)fabricated reclaimed steelwork can be fabricated and CE
marked in accordance with BS EN 1090.
STRUCTURAL STEEL REUSE –
ASSESSMENT, TESTING AND DESIGN PRINCIPLES
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... Nonetheless, the requirements of AISC 360-10 in Appendix 5, which is devoted to evaluate the existing structures and the Mechanical Testing of ASTM A370 can be followed to run a testing program when the original drawings and specifications of the building are not available [13]. In the last two decades some prominent engineering institutions have established design guidelines to the design for deconstruction practice, for instance SCI, the Steel Construction Institute [14], CIRIA, a British Construction Research Association [15], [16]. ...
... It is highly important to mention that reclaimed steel should not be employed in structures subject to earthquakes, fatigue, or in plastic design which depends on formation of plastic hinges. The SCI [14] suggests a protocol based on that reclaimed steel can be used in Consequence class 1, 2 or 3 structures given in Table B1 of BS EN 1990 [18]. Only new steel sections are allowed to be used for curved members, because the reclaimed steel must not processed through a bending machine. ...
... For the ultimate limit states, the particular partial factors γMi for buildings of both new and reused steelwork can be given in Table 1. Reclaimed steel [14] γM0 ...
Article
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Design for deconstruction, Reclaimed (salvaged) steelwork, Embodied energy, Sustainable development, CO2 emission. The aim of this research is to investigate the sustainability of design for deconstruction on saving: natural raw materials, embodied energy and carbon emission of steel buildings. A methodology is devised to account for designed for upcoming reclaim at the early planning phase. The procedure is relied on PAS2050 method. A steel structure building of two bays of size (6m x 8m) and of 4m height is devoted as a case study to assess the methodology. In this case study, three different floor systems are suggested: composite steel deck, hollow core precast concrete planks, and demountable precast composite floor system. The reduced quantity of embodied carbon energy is estimated through considering the steel building. The calculation of embodied carbon of the three models is relied on records of the Inventory of Carbon and Energy (ICE). The results show that CO2 emissions from the building can be dropped around 50%, when design for deconstruction strategy is considered. Design standards and codes lack a little procedure to follow. Therefore, this study also outlines some helpful specifications, guidelines, and detailing of design for deconstruction of steel buildings.
... Nonetheless, the requirements of AISC 360-10 in Appendix 5, which is devoted to evaluate the existing structures and the Mechanical Testing of ASTM A370 can be followed to run a testing program when the original drawings and specifications of the building are not available [13]. In the last two decades some prominent engineering institutions have established design guidelines to the design for deconstruction practice, for instance SCI, the Steel Construction Institute [14], CIRIA, a British Construction Research Association [15], [16]. ...
... It is highly important to mention that reclaimed steel should not be employed in structures subject to earthquakes, fatigue, or in plastic design which depends on formation of plastic hinges. The SCI [14] suggests a protocol based on that reclaimed steel can be used in Consequence class 1, 2 or 3 structures given in Table B1 of BS EN 1990 [18]. Only new steel sections are allowed to be used for curved members, because the reclaimed steel must not processed through a bending machine. ...
... For the ultimate limit states, the particular partial factors γMi for buildings of both new and reused steelwork can be given in Table 1. Reclaimed steel [14] γM0 ...
Article
Full-text available
The aim of this research is to investigate the sustainability of design for deconstruction on saving: natural raw materials, embodied energy and carbon emission of steel buildings. A methodology is devised to account for designed for upcoming reclaim at the early planning phase. The procedure is relied on PAS2050 method. A steel structure building of two bays of size (6m x 8m) and of 4m height is devoted as a case study to assess the methodology. In this case study, three different floor systems are suggested: composite steel deck, hollow core precast concrete planks, and demountable precast composite floor system. The reduced quantity of embodied carbon energy is estimated through considering the steel building. The calculation of embodied carbon of the three models is relied on records of the Inventory of Carbon and Energy (ICE). The results show that CO2 emissions from the building can be dropped around 50%, when design for deconstruction strategy is considered. Design standards and codes lack a little procedure to follow. Therefore, this study also outlines some helpful specifications, guidelines, and detailing of design for deconstruction of steel buildings.
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Using reclaimed structural steel on a project is an effective strategy to cut the environmental impacts associated with the production of new steel. This practice cannot be generalised to all structural steel however, as not all components can be effectively or safely reused. This paper focuses on single-storey buildings, which are particularly attractive for reclaiming and reusing structural steel. Functional reusability requirements are set out below, in particular, the requirements related to the adequacy and reliability assessment of the reclaimed steel, to ensure that (i) the reclaimed material satisfies the performance requirements, which are essential for the mechanical, physical, dimensional, and/or other relevant properties of steel materials to ensure their adequacy to be used in structural design to EN 1993, (ii) the salvaged material meets the quality requirements from nominal specifications to ensure their reliability to be used in the structural design to EN 1993, and (iii) structures made from reclaimed steel have continued integrity.
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