Structural use of steelwork in building.Part 1: Code of practice for design — Rolled and welded sections

222 Pages·2004·10.744 MB·English

BS 5950-1:2000
BRITISH STANDARD
Incorporating
Corrigendum No. 1
Structural use of
steelwork in building —
Part 1: Code of practice for design —
Rolled and welded sections
I
S
B

©

,
y
p
o
C

d
e
l
l
o
r
t
n
o
c
n
U

,
4
0
0
2
/
4
0
/
7
0

,
d
t
L

l
e
t
h
c
e
B ICS: 91.080.10
:
y
p
o
c

d
e
s
n
e
c NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW
i
L
BS 5950-1:2000
Committees responsible for this
British Standard
The preparation of this British Standard was entrusted by Technical
Committee B/525, Building and civil engineering structures, to Subcommittee
B/525/31, Structural use of steel, upon which the following bodies were
represented:
British Constructional Steelwork Association
Building Research Establishment Ltd
Cold Rolled Sections Association
Confederation of British Metalforming
DETR (Construction Directorate)
DETR (Highways Agency)
Health and Safety Executive
Institution of Civil Engineers
Institution of Structural Engineers
Steel Construction Institute
UK Steel Association
Welding Institute
I
S
B

©

,
y
p
o
C

d
e
l
l
o
r
t
n
o
c
n
U

,
4 This British Standard, having
0 been prepared under the
0 direction of the Civil
2 Engineering and Building
/
4 Structures Standards Policy
0 Committee, was published
/ under the authority of the
7 Standards Committee on
0
15May2001. It comes into
, effect on 15 August 2001
d (seeforeword).
t
L Amendments issued since publication
©BSI05-2001
l
e
t Amd. No. Date Comments
h
c
e The following BSI references 13199 May 2001 Corrected and reprinted
B relate to the work on this Corrigendum No.1
: standard:
y
p CommitteereferenceB/525/31
o Draft for comment 98/102164 DC
c

d
e
s
n ISBN0 58033239X
e
c
i
L
BS 5950-1:2000
Contents
Page
Committees responsible Inside front cover
Foreword v
Section 1. General 1
1.1 Scope 1
1.2 Normative references 1
1.3 Terms and definitions 2
1.4 Major symbols 6
1.5 Other materials 8
1.6 Design documents 8
1.7 Reference to BS5400-3 8
Section 2. Limit states design 9
2.1 General principles and design methods 9
2.2 Loading 11
2.3 Temperature change 11
2.4 Ultimate limit states 11
2.5 Serviceability limit states 23
Section 3. Properties of materials and section properties 25
3.1 Structural steel 25
I
S 3.2 Bolts and welds 26
B
3.3 Steel castings and forgings 26
©
3.4 Section properties 27
,
y 3.5 Classification of cross-sections 29
p
3.6 Slender cross-sections 36
o
C Section 4. Design of structural members 41

d 4.1 General 41
e
l 4.2 Members subject to bending 41
l
o 4.3 Lateral-torsional buckling 44
r
t 4.4 Plate girders 63
n
4.5 Web bearing capacity, buckling resistance and stiffener design 72
o
c 4.6 Tension members 77
n
U 4.7 Compression members 78

, 4.8 Members with combined moment and axial force 98
4
0 4.9 Members with biaxial moments 103
0
2 4.10 Members in lattice frames and trusses 105
/
4.11 Gantry girders 105
4
0 4.12 Purlins and side rails 106
/
7 4.13 Column bases 108
0
4.14 Cased sections 110
,
d 4.15 Web openings 112
t
L 4.16 Separators and diaphragms 114

4.17 Eccentric loads on beams 114
l
e Section 5. Continuous structures 115
t
h 5.1 General 115
c
e 5.2 Global analysis 116
B
: 5.3 Stability out-of-plane for plastic analysis 118
y
p 5.4 Continuous beams 120
o
5.5 Portal frames 121
c
5.6 Elastic design of multi-storey rigid frames 125
d
e 5.7 Plastic design of multi-storey rigid frames 126
s
n
e
c
i i
L © BSI 05-2001
BS 5950-1:2000
Page
Section 6. Connections 129
6.1 General recommendations 129
6.2 Connections using bolts 131
6.3 Non-preloaded bolts 134
6.4 Preloaded bolts 139
6.5 Pin connections 142
6.6 Holding-down bolts 143
6.7 Welded connections 144
6.8 Design of fillet welds 147
6.9 Design of butt welds 150
Section 7. Loading tests 153
7.1 General 153
7.2 Test conditions 153
7.3 Test procedures 154
7.4 Relative strength coefficient 155
7.5 Proof test 156
7.6 Strength test 157
7.7 Failure test 158
Annex A (informative) Safety format in BS5950-1 and references to
BS5400-3 161
Annex B (normative) Lateral-torsional buckling of members subject to
bending 163
I
S Annex C (normative) Compressive strength 171
B
Annex D (normative) Effective lengths of columns in simple structures 172

© Annex E (normative) Effective lengths of compression members in

, continuous structures 178
y
p Annex F (normative) Frame stability 187
o
Annex G (normative) Members with one flange laterally restrained 188
C
Annex H (normative) Web buckling resistance 199
d
e Annex I (normative) Combined axial compression and bending 207
l
l Bibliography 213
o
r Figure 1 — Example of tying the columns of a building 21
t
n Figure 2 — Example of general tying of a building 23
o
Figure 3 — Staggered holes 28
c
n Figure 4 — Angle with holes in both legs 28
U
Figure 5 — Dimensions of compression elements 29
,
4 Figure 6 — Dimensions of compound flanges 31
0
0 Figure 7 — Stress ratio for a semi-compact web 35
2
/ Figure 8 — Doubly symmetric slender cross-sections 37
4
Figure 9 — Effective width for class 4 slender web under pure bending 39
0
/ Figure 10 — Examples of lipped I-sections with compression flange lips 57
7
0 Figure 11 — Cross-sections comprising elements with differing design

, strengths 63
d
Figure 12 — Interaction between shear and moment 65
t
L Figure 13 — Stiff bearing length 73

l Figure 14 — Rolled I- or H-section with welded flange plates 80
e
t Figure 15 — Effective area of a baseplate 108
h
c Figure 16 — Proportions of standard castellated members 114
e
B Figure 17 — Dimensions of a haunch 120
:
y
p
o
c

d
e
s
n
e
c
i
L ii © BSI 05-2001
BS 5950-1:2000
Page
Figure 18 — Portal frame definitions 122
Figure 19 — Haunch restraints 125
Figure 20 — Column web panel zone 131
Figure 21 — Minimum edge and end distances 132
Figure 22 — Block shear — Effective shear area 134
Figure 23 — Lap length of a splice 135
Figure 24 — Maximum cross-centres of bolt lines for the simplemethod 138
Figure 25 — Design of outstands 139
Figure 26 — Pin-ended tension members 142
Figure 27 — Welded end connections 145
Figure 28 — Welded connection to an unstiffened flange 147
Figure 29 — Effective throat size a of a fillet weld 148
Figure 30 — Deep penetration fillet weld 148
Figure 31 — Fillet welds — Directional method 150
Figure 32 — Partial penetration butt welds 151
Figure D.1 — Side column without intermediate lateral restraint 173
Figure D.2 — Side column with intermediate lateral restraint to both
flanges 174
Figure D.3 — Simple side column with crane gantry beams 175
Figure D.4 — Compound side column with crane gantry beams 176
Figure D.5 — Compound valley column with crane gantry beams 177
Figure E.1 — Effective length ratio L /L for the non-sway buckling mode 180
I E
S Figure E.2 — Effective length ratio L /L for the sway buckling mode 181
B E

© Figure E.3 — Distribution factors for continuous columns 182

, Figure E.4 — Effective length ratio LE/L with partial sway bracing of
y
p relative stiffness kp = 1 184
o
C Figure E.5 — Effective length ratio LE/L with partial sway bracing of

d relative stiffness kp = 2 185
e
Figure G.1 — Members with one flange restrained 189
l
l Figure G.2 — Types of haunches 190
o
r Figure G.3 — Dimensions defining taper factor 193
t
n Figure G.4 — Value of (cid:1) 195
o t
c Figure G.5 — Conservative moment gradients 197
n
U Figure G.6 — Moment ratios 198

, Figure H.1 — Anchor force Hq 204
4
0 Figure H.2 — Single stiffener end posts 205
0
2 Figure H.3 — Twin stiffener end posts 206
/
Figure H.4 — Anchor panels 206
4
0 Table 1 — Limit states 10
/
7 Table 2 — Partial factors for loads (cid:2) 12
0 f
Table 3 — Factor K for type of detail, stress level and strain conditions 17
,
d Table 4 — Thickness t for plates, flats and rolled sections 18
t 1
L
Table 5 — Thickness t for structural hollow sections 19
1
l
e Table 6 — Maximum thickness t2 (mm) 20
t
h Table 7 — Charpy test temperature or equivalent test temperature T 20
27J
c
e Table 8 — Suggested limits for calculated deflections 24
B
: Table 9 — Design strength p 25
y y
p Table 10 — Strength and elongation of welds 26
o
c Table 11 — Limiting width-to-thickness ratios for sections other than

CHS and RHS 32
d
e Table 12 — Limiting width-to-thickness ratios for CHS and RHS 33
s
n
e
c
i iii
L © BSI 05-2001
BS 5950-1:2000
Page
Table 13 — Effective length L for beams without intermediate restraint 47
E
Table 14 — Effective length L for cantilevers without intermediate
E
restraint 48
Table 15 — Limiting value of L /r for RHS 49
E y
Table 16 — Bending strength p (N/mm2) for rolled sections 51
b
Table 17 — Bending strength p (N/mm2) for welded sections 52
b
Table 18 — Equivalent uniform moment factor m for lateral-torsional
LT
buckling 53
Table 19 — Slenderness factor (cid:3) for sections with two plain flanges 56
Table 20 — Bending strength p (N/mm2) for rolled sections with equal
b
flanges 59
Table 21 — Shear buckling strength q (N/mm2) of a web 67
w
Table 22 — Nominal effective length L for a compression member 79
E
Table 23 — Allocation of strut curve 81
Table 24 — Compressive strength p (N/mm2) 82
c
Table 25 — Angle, channel and T-section struts 94
Table 26 — Equivalent uniform moment factor m for flexural buckling 104
Table 27 — Empirical values for purlins 107
Table 28 — Empirical values for side rails 108
Table 29 — Minimum edge and end distances of bolts 133
I Table 30 — Shear strength of bolts 135
S
B Table 31 — Bearing strength of bolts 136

© Table 32 — Bearing strength pbs of connected parts 136

, Table 33 — Standard dimensions of holes for non-preloaded bolts 137
y
p Table 34 — Tension strength of bolts 138
o
Table 35 — Slip factors for preloaded bolts 140
C
Table 36 — Standard dimensions of holes for preloaded bolts 142
d
e Table 37 — Design strength of fillet welds p 149
l w
l Table 38 — Statistical factor k 159
o
r Table A.1 — Comparison of partial factors 163
t
n Table D.1 — Effective lengths of columns for internal platform floors 178
o
c Table E.1 — Stiffness coefficients Kb of beams in buildings with floor
n
slabs 182
U
Table E.2 — General stiffness coefficients K for beams 186
, b
4
Table E.3 — Approximate values of K for beams subject to axial
0 b
0 compression 186
2
/ Table G.1 — Equivalent uniform moment factor m 196
4 t
0
/
7
0

,
d
t
L

l
e
t
h
c
e
B
:
y
p
o
c

d
e
s
n
e
c
i
L iv © BSI 05-2001
BS 5950-1:2000
Foreword
This part of BS5950 supersedes BS5950-1:1990, which is withdrawn. A period
of three months is being allowed for users to convert to the new standard. This
edition introduces technical changes based on a review of the standard, but it
does not constitute a full revision.
This new edition has been prepared following the issue of a number of new
related standards adopting European or international standards for materials
and processes, plus revisions to standards for loading. It also reflects the transfer
of cold formed structural hollow sections from BS5950-5 to BS5950-1.
Clauses updated technically include those for sway stability, avoidance of
disproportionate collapse, resistance to brittle fracture, local buckling,
lateral-torsional buckling, shear resistance, stiffeners, members subject to
combined axial force and bending moment, joints, connections and testing. In all
cases the reason for changing the recommendations on a topic is structural
safety, but where possible some adjustments based on improved knowledge have
also been made to the recommendations on these topics to offset potential
reductions in economy.
Some of the text has been edited to reduce the risk of misapplication. In addition
some topics omitted until now have been added from BS449, including
separators and diaphragms and eccentric loads on beams.
BS5950 is a standard combining codes of practice covering the design,
construction and fire protection of steel structures and specifications for
materials, workmanship and erection. It comprises the following parts:
I
S — Part 1: Code of practice for design — Rolled and welded sections;
B
— Part 2: Specification for materials, fabrication and erection — Rolled and
©
welded sections;

,
— Part 3: Design in composite construction — Section 3.1: Code of practice for
y
p design of simple and continuous composite beams;
o
C — Part 4: Code of practice for design of composite slabs with profiled steel

sheeting;
d
e — Part 5: Code of practice for design of cold formed thin gauge sections;
l
l — Part 6: Code of practice for design of light gauge profiled steel sheeting;
o
r — Part 7: Specification for materials, fabrication and erection — Cold formed
t
n sections and sheeting;
o
c — Part 8: Code of practice for fire resistant design;
n
U — Part 9: Code of practice for stressed skin design.

,
4
0
0
2
/
4
0
/
7
0

,
d
t
L

l
e
t
h
c
e
B
:
y
p
o
c

d
e
s
n
e
c
i v
L © BSI 05-2001
BS 5950-1:2000
Part 1 gives recommendations for the design of simple and continuous steel
structures, using rolled and welded sections. Its provisions apply to the majority
of such structures, although it is recognized that cases will arise when other
proven methods of design may be more appropriate.
This part does not apply to other steel structures for which appropriate British
Standards exist.
It has been assumed in the drafting of this British Standard that the execution of
its provisions is entrusted to appropriately qualified and experienced people and
that construction and supervision will be carried out by capable and experienced
organizations.
As a code of practice, this British Standard takes the form of guidance and
recommendations. It should not be quoted as if it were a specification and
particular care should be taken to ensure that claims of compliance are not
misleading. For materials and workmanship reference should be made to
BS5950-2. For erection, reference should be made to BS5950-2 and BS5531.
A British Standard does not purport to include all the necessary provisions of a
contract. Users of British Standards are responsible for their correct application.
Compliance with a British Standard does not of itself confer immunity
from legal obligations.
I
S
B

©

,
y
p
o
C

d
e
l
l
o
r
t
n
o
c
n
U

,
4
0
0
2
/
4
0
/
7
0

,
d
t
L Summary of pages

l This document comprises a front cover, an inside front cover, pages i to vi,
e
t pages1to 213 and a back cover.
h
c
The BSI copyright notice displayed in this document indicates when the
e
B document was last issued.
:
y
p
o
c

d
e
s
n
e
c
i
L vi © BSI 05-2001
BS 5950-1:2000
Section 1. General
1
1.1 Scope
This part of BS 5950 gives recommendations for the design of structural steelwork using hot rolled steel
sections, flats, plates, hot finished structural hollow sections and cold formed structural hollow sections, in
buildings and allied structures not specifically covered by other standards.
NOTE 1 These recommendations assume that the standards of materials and construction are as specified in BS 5950-2.
NOTE 2 Design using cold formed structural hollow sections conforming to BS EN 10219 is covered by this part of BS 5950. Design
using other forms of cold formed sections is covered in BS 5950-5.
NOTE 3 Design for seismic resistance is not covered in BS 5950.
NOTE 4 The publications referred to in this standard are listed on page 213.
Detailed recommendations for practical direct application of “second order” methods of global analysis
(based on the final deformed geometry of the frame), including allowances for geometrical imperfections
and residual stresses, strain hardening, the relationship between member stability and frame stability and
appropriate failure criteria, are beyond the scope of this document. However, such use is not precluded
provided that appropriate allowances are made for these considerations (see 5.1.1).
The test procedures of 7.1.2 are intended only for steel structures within the scope of this part of BS5950.
Other cases are covered in Section 3.1 or Parts 4, 5, 6 and 9 of BS 5950 as appropriate.
1.2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute
provisions of this British Standard. For dated references, subsequent amendments to, or revisions of, any
I
S of these publications do not apply. For undated references, the latest edition of the publication referred to
B
applies.

©
BS2573-1, Rules for the design of cranes — Part 1: Specification for classification, stress calculations and
, design criteria for structures.
y
p BS 2853, Specification for the design and testing of steel overhead runway beams.
o
C
BS3100, Specification for steel castings for general engineering purposes.
d
e BS4395-1, Specification for high strength friction grip bolts and associated nuts and washers for structural
l engineering — Part 1: General grade.
l
o
r BS4395-2, Specification for high strength friction grip bolts and associated nuts and washers for structural
t engineering — Part 2: Higher grade bolts and nuts and general grade washers.
n
o BS4449, Specification for carbon steel bars for the reinforcement of concrete.
c
n
BS 4482, Specification for cold reduced steel wire for the reinforcement of concrete.
U

, BS 4483, Steel fabric for the reinforcement of concrete.
4
0 BS4604-1, Specification for the use of high strength friction grip bolts in structural steelwork —
0
Metricseries— Part 1: General grade.
2
/
4 BS4604-2, Specification for the use of high strength friction grip bolts in structural steelwork —
0 Metricseries— Part 2: Higher grade (parallel shank).
/
7
BS5400-3, Steel, concrete and composite bridges — Part 3: Code of practice for the design of steel bridges.
0

, BS5950-2, Structural use of steelwork in building — Part 2: Specification for materials, fabrication and
d erection — Rolled and welded sections.
t
L
BS5950-3, Structural use of steelwork in building — Part 3: Design in composite construction —

l Section3.1: Code of practice for design of simple and continuous composite beams.
e
t BS5950-4, Structural use of steelwork in building — Part 4: Code of practice for design of composite slabs
h
c with profiled steel sheeting.
e
B BS5950-5, Structural use of steelwork in building — Part 5: Code of practice for design of cold formed thin
:
gauge sections.
y
p
o BS5950-6, Structural use of steelwork in building — Part 6: Code of practice for design of light gauge
c profiled steel sheeting.

d
BS5950-9, Structural use of steelwork in building — Part 9: Code of practice for stressed skin design.
e
s
n
e
c
i 1
L © BSI 05-2001
BS 5950-1:2000 Section 1
BS6399-1, Loading for buildings — Part 1: Code of practice for dead and imposed loads.
BS6399-2, Loading for buildings — Part 2: Code of practice for wind loads.
BS6399-3, Loading for buildings — Part 3: Code of practice for imposed roof loads.
BS7419, Specification for holding down bolts.
BS7608, Code of practice for fatigue design and assessment of steel structures.
BS7644-1, Direct tension indicators — Part 1: Specification for compressible washers.
BS7644-2, Direct tension indicators — Part 2: Specification for nut face and bolt face washers.
BS7668, Specification for weldable structural steels — Hot finished structural hollow sections in weather
resistant steels.
BS8002, Code of practice for earth retaining structures.
BS8004, Code of practice for foundations.
BS8110-1, Structural use of concrete — Part 1: Code of practice for design and construction.
BS 8110-2, Structural use of concrete — Part 2: Code of practice for special circumstances.
BSEN10002-1, Tensile testing of metallic materials — Part 1: Method of test at ambient temperature.
BSEN10025, Hot rolled products of non-alloy structural steels — Technical delivery conditions.
BSEN10113-2, Hot-rolled products in weldable fine grain structural steels — Part 2: Delivery conditions
I for normalized/normalized rolled steels.
S
B BSEN10113-3, Hot-rolled products in weldable fine grain structural steels — Part 3: Delivery conditions

© for thermomechanical rolled steels.

, BSEN10137-2, Plates and wide flats made of high yield strength structural steels in the quenched and
y
tempered or precipitation hardened conditions — Part 2: Delivery conditions for quenched and tempered
p
o steels.
C
BSEN10155, Structural steels with improved atmospheric corrosion resistance — Technical delivery
d
e conditions.
l
l BSEN10210-1, Hot finished structural hollow sections of non-alloy and fine grain structural steels —
o
Part1: Technical delivery requirements.
r
t
n BSEN10219-1, Cold formed welded structural hollow sections of non-alloy and fine grain steels —
o Part1:Technical delivery requirements.
c
n
BSEN10250-2, Open die steel forgings for general engineering purposes — Part 2: Non-alloy quality and
U
special steels.
,
4 BSEN22553, Welded, brazed and soldered joints — Symbolic representation on drawings.
0
0 CP2, Earth retaining structures. Civil Engineering Code of Practice No. 2. London: The Institution of
2
/ Structural Engineers, 1951.
4
0 CP3:Ch V:Part 2, Code of basic data for the design of buildings — Chapter V: Loading — Part 2: Wind loads.
/
7 London: BSI, 1972.
0
NOTE Publications to which informative reference is made for information or guidance are listed in the Bibliography.
,
d 1.3 Terms and definitions
t
L
For the purposes of this part of BS5950, the following terms and definitions apply.
l
e 1.3.1
t
h beam
c
e a member predominantly subject to bending
B
: 1.3.2
y
p brittle fracture
o
brittle failure of steel at low temperature
c

d
e
s
n
e
c
i
L 2 © BSI 05-2001