Bsi bs en 01993 1 1 2005 + a1 2014 na + a1 2014

NA+A1:2014 to BS EN 1993-1-1:2005+A1:2014

BSI Standards Publication

UK National Annex to
Eurocode 3: Design of
steel structures
Part 1-1: General rules and rules
for buildings


NA+A1:2014 to BS EN 1993-1-1:2005+A1:2014

BRITISH STANDARD

Publishing and copyright information
The BSI copyright notice displayed in this document indicates when the
document was last issued.
© The British Standards Institution 2015.
Published by BSI Standards Limited 2015
ISBN 978 0 580 86667 8
ICS 91.080.10
The following BSI references relate to the work on this standard:
Committee reference CB/203
Draft for comment 15/30301400DC

Publication history
First published December 2008

Amendments issued since publication
Date

Text affected

30 June 2015National amendment A1:2014. See Introduction
for details


BRITISH STANDARD

NA+A1:2014 to BS EN 1993-1-1:2005+A1:2014

Contents
Introduction  1
NA.1Scope  1
NA.2 Nationally Determined Parameters  1
NA.3 Decisions on the status of informative annexes  8
NA.4 References to non-contradictory complementary information  9
Bibliography  10
Tables
Table NA.1 – Selection of buckling curve for a cross-section  5
Table NA.2 – Suggested limits for vertical deflections  6
Table NA.3 – Suggested limits for horizontal deflections  7
Table NA.4 – Scope and conditions of application of execution class  8 

 

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BRITISH STANDARD


BRITISH STANDARD



NA+A1:2014 to BS EN 1993-1-1:2005+A1:2014

National Annex (informative) to
BS EN 1993-1-1:2005, Eurocode 3: Design
of steel structures – Part 1-1: General rules
and rules for buildings

Introduction
This National Annex has been prepared by BSI Subcommittee CB/203,
Design & execution of steel structures. It is to be used in conjunction
with BS EN 1993-1-1:2005+A1:2014.
NA+A1:2014 to BS EN 1993-1-1:2005+A1:2014 supersedes
NA to BS EN 1993-1-1:2005, which is withdrawn.
The start and finish of text introduced or altered by National
Amendment 1 is indicated in the text by tags . Minor editorial
changes are not tagged.



NA.1Scope

This National Annex gives:
a) the decisions for the National Determined Parameters described
in the following subclauses of BS EN 1993-1-1:2005+A1:2014:
•
•
•
•
•
•
•
•
•

2.3.1(1)
3.1(2)
3.2.1(1)
3.2.2(1)
3.2.3(1)
3.2.3(3)B
3.2.4(1)B
5.2.1(3)
5.2.2(8)

•
•
•
•
•
•
•

•
•

5.3.2(3)
5.3.2(11)
5.3.4(3)
6.1(1)
6.1(1)B
6.3.2.2(2)
6.3.2.3(1)
6.3.2.3(2)
6.3.2.4(1)B

•
•
•
•
•
•
•
•
•

6.3.2.4(2)B
6.3.3(5)
6.3.4(1)
7.2.1(1)B
7.2.2(1)B
7.2.3(1)B
BB.1.3(3)B

C.2.2(3)
C.2.2(4)

b) Decisions on the status of BS EN 1993-1-1:2005+A1:2014
informative annexes; and
c) References to non-contradictory complementary information.



NA.2 Nationally Determined Parameters

NA.2.1
General
Decisions for the Nationally Determined Parameters decided in
BS EN 1993-1-1:2005+A1:2014 are given in clauses NA.2.2 to NA.2.27.

NA.2.2
Actions and environmental

influences
[BS EN 1993-1-1:2005+A1:2014, 2.3.1(1)]
There are no additional regional, climatic or accidental situations
to consider.

 

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NA+A1:2014 to BS EN 1993-1-1:2005+A1:2014

BRITISH STANDARD

NA.2.3
Other Steel material

and products
[BS EN 1993-1-1:2005+A1:2014, 3.1(2)]
If other steels are used, due allowance should be made for
variations in properties, including ductility and weldability. Further
information on the ductility requirements for steel is given in
BS EN 1993-1-1:2005+A1:2014, 3.2.2(1).
Steel castings and forgings may be used for components in bearings,
junctions and other similar parts. Castings should conform to
BS EN 10293 and forgings should conform to BS EN 10250-2. Further
guidance on steel castings is given in reference [1].
For higher strength steels see BS EN 1993-1-12.

NA.2.4
Material properties

[BS EN 1993-1-1:2005+A1:2014, 3.2.1(1)]
The nominal values of the yield strength fy and the ultimate strength
fu for structural steel should be those obtained from the product
standard. The ultimate strength fu should be taken as the lowest value
of the range given for Rm in the product standard. Further information
on the yield and ultimate strength for structural steel is also given in
NA.4.

NA.2.5

Ductility requirements

[BS EN 1993-1-1:2005+A1:2014, 3.2.2(1)]
a) Elastic global analysis
The limiting values for the ratio fu/fy, the elongation at failure and the
ultimate strain εu for elastic global analysis are given below.
fu/fy, H 1.10;
Elongation at failure not less than 15%;

εu H 15εy.
b) Plastic global analysis
Plastic global analysis should not be used for bridges. For buildings
the limiting values for the ratio fu/fy, the elongation at failure and the
ultimate strain εu for plastic global analysis are given below.
fu/fy H 1.15;
Elongation at failure not less than 15%;

εu H 20εy.
NA.2.6
Fracture toughness

[BS EN 1993-1-1:2005+A1:2014, 3.2.3(1)]
For buildings and other quasi-statically loaded structures the lowest
service temperature in the steel should be taken as the lowest air
temperature which may be taken as −5°C for internal steelwork and
−15°C for external steelwork.
For bridges the lowest service temperature in the steel should be
determined according to the NA to BS EN 1991-1-5 for the bridge
location. For structures susceptible to fatigue it is recommended that
the requirements for bridges should be applied.

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BRITISH STANDARD

NA+A1:2014 to BS EN 1993-1-1:2005+A1:2014
In other cases (e.g. the internal steelwork in cold stores) the lowest
service temperature in the steel should be taken as the lowest air
temperature expected to occur within the intended design life of
the structure.

NA.2.7
Toughness properties

for members in compression
[BS EN 1993-1-1:2005+A1:2014, 3.2.3(3)B]
The recommendations given in the NA to BS EN 1993-1-10 should
be used.

NA.2.8
Through-thickness

properties
[BS EN 1993-1-1:2005+A1:2014, 3.2.4(1)B]
The recommendations given in the NA to BS EN 1993‑1‑10 should
be used.

NA.2.9
Effects of deformed

geometry of the structure
[BS EN 1993‑1‑1:2005+A1:2014, 5.2.1(3)]
For plastic analysis of clad structures provided that the stiffening
effects of masonry infill wall panels or diaphragms of profiled steel
sheeting are not taken into account:
αcr H 10
For plastic analysis of portal frames subject to gravity loads only with
frame imperfections:
αcr H 5
provided the following conditions are satisfied:
a) The span, L, does not exceed 5 times the mean height of the
columns
b) hr satisfies the criterion:
(hr/sa)2 + (hr/sb)2 G 0.5
in which sa and sb are the horizontal distances from the apex
to the columns.
NOTE  For a symmetrical frame this expression simplifies to
hr G 0.25L.

NA.2.10
Structural stability

of frames
[BS EN 1993‑1‑1:2005+A1:2014, 5.2.2(8)]
This method should only be used for frames that comply with 5.2.2(6).
In such cases the sway moments in the beams and beam-to-column
connections should be multiplied by kr unless a smaller value is shown
to be adequate by analysis. kr may be evaluated using the following
expression provided that acr H 3.0:

kr =

1
1−

1
α cr

 

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NA+A1:2014 to BS EN 1993-1-1:2005+A1:2014

BRITISH STANDARD

NA.2.11
Design values of initial

local bow imperfection
[BS EN 1993‑1‑1:2005+A1:2014, 5.3.2(3)]
For elastic analysis of the cross-section, the initial imperfections
for an individual section about a particular axis should be
back‑calculated from the formula for the buckling curves given in
BS EN 1993-1-1:2005+A1:2014, 6.3 using the elastic section modulus.
For plastic analysis of the cross-section, the initial imperfections
for an individual section about a particular axis should be
back‑calculated from the formula for the buckling curves given
in BS EN 1993-1-1:2005+A1:2014, 6.3 using the full plastic section

modulus.

NA.2.12
Amplitude of imperfections

[BS EN 1993‑1‑1:2005+A1:2014, 5.3.2(11)]
The method given in BS EN 1993-1-1:2005+A1:2014, 5.3.2(11) should
not be used for buildings.

NA.2.13
Imperfections for

lateral-torsional bucking in bending
[BS EN 1993‑1‑1:2005+A1:2014, 5.3.4(3)]
The value of k should be taken as 1.0.

NA.2.14
Partial factors for structures not covered by BS EN 1993

Part 2 to Part 6 [BS EN 1993‑1‑1:2005+A1:2014, 6.1(1)]
For structures not covered by BS EN 1993 Part 2 to Part 6, the partial
factors should be appropriate for the structure and agreed with the
client.

NA.2.15
Partial safety factors

for buildings
[BS EN 1993‑1‑1:2005+A1:2014, 6.1(1)]
For buildings the following partial factors should be used:

γM0 = 1.00
γM1 = 1.00
γM2 = 1.10

NA.2.16
Imperfection factors

for lateral torsional buckling
[BS EN 1993‑1‑1:2005+A1:2014, 6.3.2.2(2)]
The recommended values given in BS EN 1993-1-1:2005+A1:2014,
Table 6.3 and Table 6.4 should be used.

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BRITISH STANDARD

NA+A1:2014 to BS EN 1993-1-1:2005+A1:2014

NA.2.17
Lateral torsional buckling

for rolled
sections or equivalent welded sections
[BS EN 1993‑1‑1:2005+A1:2014, 6.3.2.3(1)]
For buildings and bridges the following values of λLT,0 and β should be
used:
a) For rolled sections and hot-finished and cold-formed hollow
sections:
λLT,0 = 0.4

β = 0.75
b) For welded sections:
λLT,0 = 0.2
β = 1.00
BS EN 1993-1-1:2005+A1:2014, Table 6.5 should be replaced with
Table NA.1:

Table NA.1  Selection of buckling curve for a cross-section
Cross-section

Limits

Buckling
curve

Rolled doubly symmetric I and H sections and hot-finished
hollow sections

h/b G 2

b

2.0 < h/b G 3.1

c

h/b > 3.1

d

Angles (for moments in the major principal plane)

d

All other hot-rolled sections.

d

Welded doubly symmetric sections and cold-formed
hollow sections

h/b G 2

c

2.0 G h/b < 3.1

d

NA.2.18
Modification factor,

f
[BS EN 1993‑1‑1:2005+A1:2014, 6.3.2.3(2)]
The recommended expression for f should be used in which kc is
given by:
kc =

1
C1

where:
C1=

Mcr for the actual bending moment diagram
Mcr for a uniform bending moment diagram

values of C1 are given in the references listed in NA.4.

NA.2.19
The slenderness limit

λc0
[BS EN 1993‑1‑1:2005+A1:2014, 6.3.2.4(1)B]
For I, H, channel and box sections used in buildings the value of λc0
should be taken as 0.4.

 

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NA+A1:2014 to BS EN 1993-1-1:2005+A1:2014

BRITISH STANDARD

NA.2.20
Modification factor,

kfl

[BS EN 1993‑1‑1:2005+A1:2014, 6.3.2.4(2)B]
The value of the modification factor kfl should be taken as:
kfl = 1.0 for hot rolled I-sections;
kfl =1.0 for welded I-sections with h/b G 2;
kfl = 0.9 for other sections.

NA.2.21
Interactions factors

kyy, kyz, kzy and kzz
[BS EN 1993‑1‑1:2005+A1:2014, 6.3.3(5)]
The interaction factors kyy, kyz, kzy, kzz for doubly symmetric sections
may be determined using either alternative Method 1 (given in
BS EN 1993-1-1:2005+A1:2014, Annex A) or alternative Method 2
(given in BS EN 1993-1-1:2005+A1:2014, Annex B). Alternative
Method 2 (given in BS EN 1993-1-1:2005+A1:2014, Annex B) may also
be used for sections that are not doubly symmetric when modified in
accordance with NA.3.2.

NA.2.22
General method for

lateral and lateral
torsional buckling of structural components
[BS EN 1993‑1‑1:2005+A1:2014, 6.3.4(1)]
This method is only valid for nominally straight components subject to
in-plane monoaxial bending and/or compression.
In this method χop should be taken as the minimum value
of χ and χLT. Where χ is determined in accordance with
BS EN 1993-1-1:2005+A1:2014, 6.3.1 for lateral buckling and χLT is

determined in accordance with BS EN 1993-1-1:2005+A1:2014, 6.3.2
for lateral torsional buckling.

NA.2.23
Vertical deflections

[BS EN 1993‑1‑1:2005+A1:2014, 7.2.1(1)B]
Table NA.2 gives suggested limits for calculated vertical deflections
of certain members under the characteristic load combination due to
variable loads and should not include permanent loads. Circumstances
may arise where greater or lesser values would be more appropriate.
Other members may also need deflection limits.
On low pitch and flat roofs the possibility of ponding should be
investigated.

Table NA.2  Suggested limits for vertical deflections
Vertical deflection
Cantilevers

Length/180

Beams carrying plaster or other brittle finish

Span/360

Other beams (except purlins and sheeting rails)

Span/200

Purlins and sheeting rails

To suit the characteristics of particular cladding

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BRITISH STANDARD

NA+A1:2014 to BS EN 1993-1-1:2005+A1:2014

NA.2.24
Horizontal deflections

[BS EN 1993‑1‑1:2005+A1:2014, 7.2.2(1)B]
Table NA.3 gives suggested limits for calculated horizontal deflections
of certain members under the characteristic load combination due to
variable load. Circumstances may arise where greater or lesser values
would be more appropriate. Other members may also need deflection
limits.

Table NA.3  Suggested limits for horizontal deflections
Horizontal deflection
Tops of columns in single-storey buildings except
portal frames

Height/300

Columns in portal frame buildings, not
supporting crane runways

To suit the characteristics of the particular
cladding

In each storey of a building with more than one
storey

Height of that storey/300

NA.2.25
Dynamic effects

[BS EN 1993‑1‑1:2005+A1:2014, 7.2.3(1)B]
Reference should be made to specialist literature as appropriate. For
floor vibrations see NA.4.

NA.2.26
Hollow section buckling

lengths in lattice girders
[BS EN 1993‑1‑1:2005+A1:2014, BB.1.3(3)B]
The recommended values may be used and further information is
given in NA.4.



NA.2.27

Selection of execution class
[BS EN 1993-1-1:2005+A1:2014, C.2.2(3) and C.2.2(4)]

NA.2.27.1
General
BS EN 1993-1-1:2005+A1:2014, Table C.1 should not be adopted.
Decisions for the selection of reliability class and consequences class
are given in clause NA.2.27.2.
Decisions for the selection of execution class (EXC) are given in
clause NA.2.27.3.

NA.2.27.2
Selection of reliability class and consequences class
If the application of design rules in a particular part of BS EN 1993 is
specified in terms of reliability class (RC) or consequences class (CC),
such classes should apply.
Otherwise it should be assumed that the design rules in BS EN 1993
are safe for classes up to and including RC2 and CC2, as defined in
BS EN 1990.

 

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NA+A1:2014 to BS EN 1993-1-1:2005+A1:2014


NA.2.27.3

BRITISH STANDARD

Selection of execution class

Execution class should be selected taking into account the parts of
BS EN 1993 and other Eurocodes that are applicable to the design of
the structure.
The selection of execution class is given in Table NA.4.
NOTE 1  In order to ensure full compatibility with the design resistance
values in BS EN 1993, technical requirements in BS EN 1090-2 relating to
certain execution classes might need to be enhanced. Guidance is given
in PD 6705-2 for designs to BS EN 1993-2. Subject to the limitations in
its scope of materials and processes, PD 6705-2 might also be used to
provide guidance for other designs covered by Table NA.4. If BS EN 1998
applies to a design, Quantified Service Categories F71, F90 and F112 might
be deemed to apply to yielding/dissipative elements with ductility classes
DCL, DCM and DCH respectively.

Table NA.4  Scope and conditions of application of execution class
Parts of BS EN 1993 which are
applicable to the design of the
structure(1)

All relevant Parts
except Part 1-9 or
Part 1-12

All relevant Parts including Part 1-9
and/or Part 1-12

Other Eurocodes
applicable to the
design of the
structure(1) (in addition

to BS EN 1990 and
BS EN 1991)

Required

−

−

BS EN 1998

Optional

BS EN 1994

BS EN 1994

BS EN 1994

Execution classes

RC1, CC1,
RC2, CC2

Minimum EXC2

Generally EXC3

Generally EXC3

RC3, CC3

EXC3

Minimum EXC3

Minimum EXC3

Note:
(1)

  Or a distinct, clearly identifiable zone of a structure

No guidance on the scope of application of EXC1 is given. The scope
of application of EXC1 in the NOTE to BS EN 1993-1-1:2005+A1:2014,
C.2.2(4) is not endorsed for general use.
NOTE 2  The use of EXC1 generally provides a lower level of assurance
of attaining the design resistance values in BS EN 1993. If the proposed
specification of EXC1 by a specifier, either in full or in part, does not take
this into account, its use might result in a higher probability of structural
failure than is normally accepted for most structures in the UK.



NA.3 Decisions on the status of informative
annexes

NA.3.1
BS EN 1993‑1‑1:2005+A1:2014,

Annex A

BS EN 1993-1-1:2005+A1:2014, Annex A may be used. The scope
of Method 1 given in Annex A should be limited to doubly symmetric
sections.

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BRITISH STANDARD

NA+A1:2014 to BS EN 1993-1-1:2005+A1:2014

NA.3.2
BS EN 1993‑1‑1:2005+A1:2014,

Annex B

BS EN 1993-1-1:2005+A1:2014, Annex B may be used.
Where applied to sections that are not doubly symmetric λz and χ z
should be taken as the values of λ and χ from the highest value of λT
to BS EN 1993‑1‑1, 6.3.1.3 or λ to BS EN 1993‑1‑1, 6.3.1.4.
Where the sections are not I, H or hollow sections Class 1 and Class 2
sections should be designed as Class 3 sections.

NA.3.3
BS EN 1993‑1‑1:2005+A1:2014,

Annex AB

BS EN 1993-1-1:2005+A1:2014, Annex AB may be used.

NA.3.4
BS EN 1993‑1‑1:2005+A1:2014,

Annex BB

BS EN 1993-1-1:2005+A1:2014, Annex BB may be used.



NA.4 References to non-contradictory
complementary information
References cited in this National Annex to non-contradictory,
complementary information can be found at www.steel-ncci.co.uk.
Whilst this material is likely to be technically authoritative, not all
of it has been reviewed by the UK national committee, and users
should satisfy themselves of its fitness for their particular purpose. In
particular, they should be aware that material indicated as not having
been endorsed by the committee might contain elements that are in
conflict with the Eurocode.

 

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BRITISH STANDARD

Bibliography

Standards publications
For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including
any amendments) applies.
BS EN 1090-2, Execution of steel structures and aluminium
structures – Part 2: Technical requirements for the execution of steel
structures
BS EN 1990, Eurocode – Basis of structural design
BS EN 1991, Eurocode 1: Actions on structures
NA to BS EN 1991-1-5, UK National Annex to Eurocode 3: Design of
steel structures – Part 1-5: Plated structural elements
BS EN 1993 (Parts 2 to 6), Eurocode 3 – Design of steel structures
BS EN 1993-1-9, Eurocode 3: Design of steel structures – Part 1-9:
Fatigue
NA to BS EN 1993-1-10, UK National Annex to Eurocode 3: Design of
steel structures – Part 1-10: Material toughness and through-thickness
properties
BS EN 1993-1-12, Eurocode 3: Design of steel structures – Part 1-12:
Supplementary rules for high strength steels
BS EN 1994, Eurocode 4: Design of composite steel and concrete
structures
BS EN 1998, Eurocode 8: Design of structures for earthquake
resistance
BS EN 10025-2:2004, Hot rolled products of structural steels – Part 2:
Technical delivery conditions for non-alloy structural steels
BS EN 10250-2, Open steel die forgings for general engineering
purposes – Part 2: Non-alloy quality and special steels

BS EN 10293, Steel castings for general engineering uses
PD 6705-2. Published Document. Structural use of steel and
aluminium. Part 2: Recommendations for the execution of steel
bridges to BS EN 1090-2.


Other publications
[1] Castings in steel construction, SCI publication P 172, The Steel
Construction Institute, Silwood Park, Ascot, Berkshire SL5 7QN.

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