untitled

NA to BS EN 1991-1-5:2003

Contents

Introduction 1

NA.1

Scope 1

NA.2

Nationally Determined Parameters 1

NA.3

Decisions on the status of BS EN 1991-1-5:2003 informative
annexes C and D 7

Bibliography 10

List of figures
Figure NA.1 – Isotherms of minimum shade air temperature (°C) 8
Figure NA.2 – Isotherms of maximum shade air temperature (°C) 9

List of tables
Table NA.1 – Adjustment to uniform bridge temperature for deck
surfacing 3

Summary of pages
This document comprises a front cover, an inside front cover,
pages i and ii, pages 1 to 10, an inside back cover and a back cover.

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NA to BS EN 1991-1-5:2003

National Annex (informative)

to BS EN 1991-1-5:2003,

Actions on structures –

Part 1-5: General actions –

Thermal actions

Introduction

This National Annex has been prepared by BSI Subcommittee B/525/1,
Actions (loadings) and basis of design. In the UK it is to be used in
conjunction with BS EN 1991-1-5:2003.

NA.1 Scope

This National Annex gives:
a) the UK decisions for the Nationally Determined Parameters

described in the following subclauses of BS EN 1991-1-5:2003
— 5.3(2)

— 6.1.4.2(1)

— 7.2.1(1)

— 6.1.1(1)

— 6.1.4.3(1)

— 7.5(3)

— 6.1.2(2)

— 6.1.4.4(1)

— 7.5(4)

— 6.1.3.1(4)

— 6.1.5(1)

— A.1(1)

— 6.1.3.2(1)

— 6.1.6(1)

— A.1(3)

— 6.1.3.3(3)

— 6.2.1(1)P

— A.2(2)

— 6.1.4(3)

— 6.2.2(1)

— B(1)

— 6.1.4.1(1)

— 6.2.2(2)

b) the UK decisions on the status of BS EN 1991-1-5:2003

informative annexes C and D (see NA.3); and

c) references to non-contradictory complementary information.

NA.2 Nationally Determined Parameters

NA.2.1

Determination of temperature profiles
[BS EN 1991-1-5:2003, 5.3(2)]

The values recommended in BS EN 1991-1-5:2003, Table 5.1, should be
used.
The values recommended in BS EN 1991-1-5:2003, Table 5.2, should be
used, except that the minimum shade air temperature T

min

and the

maximum shade air temperature T

max

should be obtained from

Figure NA.1 and Figure NA.2, respectively.
The values recommended in BS EN 1991-1-5:2003, Table 5.3, should be
used.

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NA.2.2

Bridge deck types
[BS EN 1991-1-5:2003, 6.1.1(1), NOTE 2]

NA.2.2.1

General

Values for the uniform temperature component and temperature
difference component for buried concrete box and portal frame
structures, and masonry arch bridges with solid spandrels, are given in
NA.2.2.2 and NA.2.2.3.
Values for other types of bridges not covered in BS EN 1991-1-5 should
be agreed for the individual project with the relevant authority, where
appropriate.
The following may be considered to be protected from climatic and
operational temperature changes:
a) the walls and base slab of buried concrete box structures and the

walls of buried concrete portal frame structures;

b) in situ buried concrete structures which have over 0,6 metres of

cover (fill plus surfacing) and which are more than five times as
long (transversely) as the clear span or, for multispan structures,
five times as long as the largest clear span;

c) precast buried concrete segments which have over 0,6 metres

of cover (fill plus surfacing) and which are located more
than 1,25 times the clear span from the edge of the structure.

Buried concrete box and portal frame structures, and masonry arch
bridges with solid spandrels, should be classified as Type 3 structures.

NA.2.2.2

Uniform temperature component

For buried concrete box and portal frame structures, and masonry arch
bridges with solid spandrels, where the total cover depth from the top
of the surfacing to the top of the roof slab or extrados of the arch ring
is greater than 200 mm, the minimum and maximum uniform bridge
temperatures obtained from BS EN 1991-1-5:2003, Figure 6.1, and
adjusted using Table NA.1 may be further modified as follows:

For every additional 100 mm of total cover depth in excess
of 200 mm:
a) the minimum uniform bridge temperature may be increased

by 1 °C;

b) the maximum uniform bridge temperature may be reduced

by 2 °C.

However, the difference between the maximum and minimum
uniform bridge temperature should not be taken as less than 15 °C.

Changes in uniform bridge temperature may be ignored when the total
depth from the top of the surfacing to the top of the roof slab or
extrados of the arch ring is 1,5 m or greater.

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NA.2.2.3

Temperature difference component

BS EN 1991-5:2003, Annex B, should be used to establish temperature
differences for buried concrete box and portal frame structures, and
masonry arch bridges with solid spandrels. In BS EN 1991-5:2003,
Table B.3, the value of h for buried concrete structures should be taken
as the distance from the underside of the surfacing to the soffit of the
roof slab. For masonry arch bridges the value of h in Table B.3 should
be taken as the distance from the underside of the surfacing to the
intrados of the arch ring. In BS EN 1991-5:2003, Figure 6.2a,
Figure 6.2b and Figure 6.2c, %T

should be taken as occurring at the

underside of the surfacing and the dimensions h and h

should be

measured downwards from that level so that the temperature profiles
shown in BS EN 1991-5:2003, Figure 6.2c, are applied through the fill
as well as through the roof slab or arch ring.
Heating and cooling temperature differences may be ignored when the
total depth from the top of the surfacing to the top of the roof slab or
extrados of the arch ring exceeds 500 mm.

NA.2.3

Consideration of thermal actions
[BS EN 1991-1-5:2003, 6.1.2(2)]

Approach 2 should be used, unless the use of Approach 1 is agreed for
the individual project with the relevant authority.

NA.2.4

Uniform temperature components – General
[BS EN 1991-1-5:2003, 6.1.3.1(4)]

The values of T

e.min

and T

e.max

recommended in BS EN 1991-1-5:2003,

Figure 6.1, should be used, subject to the adjustments for deck
surfacing given in Table NA.1.
The uniform bridge temperature components are dependent on the
depth of surfacing on the bridge deck, and the values given in
BS EN 1991-1-5:2003, Figure 6.1, assume depths of 40 mm for Type 1
and 100 mm for Types 2 and 3. When the depth of surfacing differs from
these values, the minimum and maximum uniform bridge temperature
components should be adjusted by the amounts given in Table NA.1.

Table NA.1

Adjustment to uniform bridge temperature for deck surfacing

Deck
surface

Addition to minimum uniform bridge
temperature component, °C

Addition to maximum uniform bridge
temperature component, °C

Type 1

Type 2

Type 3

Type 1

Type 2

Type 3

Unsurfaced 0

Water-proofed

40 mm surfacing

100 mm surfacing

N/A

200 mm surfacing

N/A

Waterproofed deck values are conservative, assuming dark material; there may be some alleviation when light coloured
waterproofing is used; specialist advice should be sought if required.

Surfacing depths include waterproofing.

For steel truss and plate girders the values for unsurfaced and waterproofed deck surfaces may be reduced to +2 °C.

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NA.2.5

Shade air temperature
[BS EN 1991-1-5:2003, 6.1.3.2(1)]

The minimum and maximum shade air temperatures with a probability
of being exceeded of 0,02 (1 in 50 year return period) should be
obtained from the maps of isotherms in Figure NA.1 and Figure NA.2,
respectively.

NA.2.6

Range of uniform bridge temperature
component
[BS EN 1991-1-5:2003, 6.1.3.3(3)]

For bearings and expansion joints, the maximum expansion and
contraction ranges of the uniform bridge temperature component
should be as given by other relevant standards (for example,
BS EN 1993-2). Where no information is given the requirements should
be as follows:
(%T

N,exp

+ 20) °C

and
(%T

N,con

+ 20) °C,

respectively.
If the temperature at which the bearings and expansion joints are set is
specified then the ranges are (%T

N,exp

+ 10) °C and (%T

N,con

+ 10) °C,

respectively.

NA.2.7

Temperature difference components
[BS EN 1991-1-5:2003, 6.1.4(3)]

The initial temperature difference at the closure of cantilever
construction should be specified for the individual project.

NA.2.8

Vertical linear component (Approach 1)
[BS EN 1991-1-5:2003, 6.1.4.1(1)]

Generally, Approach 1 should not be used. However, where Approach 1
is specified and permitted for use, the values of %T

M,heat

and %T

M,cool

and

factor k

sur

given in BS EN 1991-1-5:2003, Table 6.1 and Table 6.2,

respectively, should be used.

NA.2.9

Vertical temperature components with
non-linear effects (Approach 2)
[BS EN 1991-1-5:2003, 6.1.4.2(1)]

The temperature difference values recommended in
BS EN 1991-1-5:2003, Figure 6.2a to Figure 6.2c, for the different
types of bridge deck should be used, but with the following changes to
Figure 6.2a and Figure 6.2c:
In Figure 6.2a:
•

In note, %T

should be %T

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In Figure 6.2c:
•

Column (a) Heating: Table: the value of %T

for h

W 0,8 should

be 13,5 instead of 13,0;

•

Column (b) Cooling: Figure: the top horizontal line for h

should

be lowered to the kink;

•

Column (b) Cooling: Below figure: line 2:

u 0,20 m instead

W 0,20 m;

•

In note, %T

should be %T

The data given in BS EN 1991-1-5:2003, Figure 6.2, assume depths of
surfacing of 40 mm for Type 1 and 100 mm for Types 2 and 3. For other
depths of surfacing different values will apply. Values for other
thicknesses of surfacing are given in BS EN 1991-1-5:2003, Annex B.

NA.2.10

Horizontal components
[BS EN 1991-1-5:2003, 6.1.4.3(1)]

Where a horizontal temperature difference needs to be considered, a
temperature difference between the outer edges of the bridge,
independent of the width of the bridge, of 5 °C may be used.
Alternatively, appropriate values may be determined from first
principles.

NA.2.11

Temperature difference components within
walls of concrete box girders
[BS EN 1991-1-5:2003, 6.1.4.4(1)]

The linear temperature difference of 15 °C recommended in
BS EN 1991-1-5:2003, 6.1.4.4(1), Note, may be used. Alternatively,
appropriate non-linear distribution and corresponding values may be
determined from first principles.

NA.2.12

Simultaneity of uniform and temperature
difference components
[BS EN 1991-1-5:2003, 6.1.5(1)]

The values of 6

= 1,00 and 6

= 1,00 may be used.

The ranges of

uniform bridge temperature component for expansion and contraction
(%T

) should be determined from the relevant value of T

and:

•

appropriate values of T

e max

above 25 °C for Type 1 and T

emax

above 15 °C for Types 2 and 3.

•

appropriate values of T

e min

of up to 8 °C below the maximum for

Type 1
T

e min

of up to 4 °C below the maximum for

Type 2
T

e min

of up to 2 °C below the maximum for

Type 3.

Alternatively, appropriate values may be determined from first
principles.

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NA.2.13

Difference in the uniform temperature
components between different structural
elements [BS EN 1991-1-5:2003, 6.1.6(1)]

Where relevant, the values for the differences in the uniform
temperature component recommended in the note to
BS EN 1991-1-5:2003, 6.1.6(1), may be used.
Alternatively, appropriate values may be determined from first
principles.

NA.2.14

Consideration of thermal actions
[BS EN 1991-1-5:2003, 6.2.1(1)P]

The design procedure to be used for taking temperature differences
between the outer faces of bridge piers may assume an equivalent linear
temperature difference.

NA.2.15

Temperature differences
[BS EN 1991-1-5:2003, 6.2.2(1)]

The linear temperature difference between the opposite outer faces of
concrete piers may be taken as 5 °C. Alternatively, appropriate values
may be determined from first principles.

NA.2.16

Temperature differences
[BS EN 1991-1-5:2003, 6.2.2(2)]

The linear temperature difference between the inner and outer faces of
walls may be taken as 15 °C. Alternatively, appropriate values may be
determined from first principles.

NA.2.17

Shade air temperature
[BS EN 1991-1-5:2003, 7.2.1(1)]

The minimum and maximum shade air temperatures with a probability
of being exceeded of 0,02 (1 in 50 year return period) should be
obtained from the maps of isotherms given in Figure NA.1 and
Figure NA.2, respectively.

NA.2.18

Values of temperature components (indicative
values) [BS EN 1991-1-5:2003, 7.5(3)]

The linear temperature difference component value of 15 °C
recommended in Note 1 to BS EN 1991-1-5:2003, 7.5(3), should be
used.

NA.2.19

Values of temperature components (indicative
values) [BS EN 1991-1-5:2003, 7.5(4)]

The value of stepped temperature component of 15 °C recommended in
the note to BS EN 1991-1-5:2003, 7.5(4), should be used.

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NA.2.20

Isotherms of national minimum shade air
temperatures – General
[BS EN 1991-1-5:2003, A.1(1)]

The minimum and maximum shade air temperatures are obtained from
the maps of isotherms in Figure NA.1 and Fi gure NA.2, respectively.
These figures relate to a 0,02 probability exceedance (1 in 50 year
return period).
The temperature values should be adjusted for height above mean
sea level using the recommended method given in
BS EN 1991-1-5:2003, A.1(1), Note 2.

NA.2.21

Isotherms of national minimum and maximum
shade air temperatures – General
[BS EN 1991-1-5:2003, A.1(3)]

In the absence of specific provisions to control the temperature at which
a bridge is restrained, the initial temperature T

should be taken as 0 °C

for expansion and 20 °C for contraction, except that, for buried
concrete box structures, the value of T

may be taken as 10 °C for both

expansion and contraction.

NA.2.22

Maximum and minimum shade air temperature
values with an annual probability of being
exceeded p other than 0,02
[BS EN 1991-1-5:2003, A.2(2)]

The values of k

, k

should be taken as 0,781, 0,056, 0,393 and

p0,156, respectively, as recommended in BS EN 1991-1-5:2003,

A.2(2), Note 1.

NA.2.23

Temperature differences for various surfacing
depths [BS EN 1991-1-5:2003, B(1)]

Temperature difference profiles for surfacing depths, other than 40 mm
for Type 1 and 100 mm for deck Types 2 and 3, should be as given in
BS EN 1991-1-5:2003, Table B.1, Table B.2 and Table B.3, except with
the following changes to Table B.3:
•

1st column: replace “0,2” with “

u 0,2”

•

1st column: replace “1,5” with “

W 1,5”

•

6th column, 1,0 m depth of slab and 200 mm surfacing thickness:
replace “4,3” with “4,8”.

NA.3 Decisions on the status of

BS EN 1991-1-5:2003 informative

annexes C and D

BS EN 1991-1-5:2003, informative annexes C and D, may be used in the
UK as informative annexes.

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Figure NA.1

Isotherms of minimum shade air temperature (°C)

NOTE The isotherms are derived from Meteorological Office Data.

About -10

-19

INVERNESS
-21

-12

-10
EDINBURGH

GLASSGOW
-19

CARLISLE

NEWCASTLE

-10 TO -12

-9

LONDONDERRY

BELFAST

DUBLIN

-16

-9

-10

CORK

-14

-7

About
-9

-10
LIVERPOOL

-16
LEEDS

SHEFFIELD

-16

-18

BIRMINGHAM
-18

NORWICH

-10

-12

-9

OXFORD

-16

BRIGHTON

-9

PLYMOUTH

EXETER

CARDIFF

LONDON
-18

-7

-9

ABERYSTWYTH

-10

-9

UTM GRID

ZONE 3OU

-9

IRISH GRID

NATIONAL GRID

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Figure NA.2

Isotherms of maximum shade air temperature (°C)

NOTE The isotherms are derived from Meteorological Office Data.

About 24

About 25

26 TO 28

INVERNESS

EDINBURGH

GLASGOW

LONDONDERRY

NEWCASTLE

NORWICH

BELFAST

About

LEEDS

LIVERPOOL

DUBLIN

CORK

IRISH GRID

NATIONAL GRID 55

UTM GRID

ZONE 3OU

About 33

PLYMOUT H

EXETER

35 LONDON

BRIGHTON

OXFORD

CARDIFF

ABERYSTWITH

CARLISLE

BIRMINGHAM

SHEFFIELD

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Bibliography

Standards publications

BS EN 1337-1, Structural bearings – Part 1: General design rules
BS EN 1337-2, Structural bearings – Part 2: Sliding elements
BS EN 1337-3, Structural bearings – Part 3: Elastomeric bearings
(in preparation)
BS EN 1337-4, Structural bearings – Part 4: Roller bearings
BS EN 1337-5, Structural bearings – Part 5: Pot bearings
BS EN 1337-6, Structural bearings – Part 6: Rocker bearings (in
preparation)
BS EN 1337-7, Structural bearings – Part 7: Spherical and
cylindrical PTFE bearings
BS EN 1990:2002, Eurocode – Basis of structural design
BS EN 1991 (all parts), Eurocode 1 – Actions on structures
BS EN 1993-2, Eurocode 3 – Design of steel structures –
Part 2: Steel bridges

Other publications

Emerson, Mary. “Temperature differences in bridges: basis of
design requirements.” Department of the Environment,
TRRL Report LR 765. Crowthorne, Berkshire, United Kingdom, 1977.

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