chapter 6 design detailing of major steel components

6. Design detailing of major steel

components

This chapter gives a comparative study of detailing practices for major steelcomponents such as beams, girders, columns, trusses, and various fastenings.Three major codes are considered and they are based on British, European andAmerican practices. Both bolted and welded connections or fastenings aregiven as practised under the BS 5950, EC3 and AISC and LRFD Codes.

67

6.1. Beams and girders

Fig. 6.1.1. Notching of flanges—bolted connection, all beams gradeS275 (based on EC3 specifications)

68

STRUCTURAL DETAILING IN STEEL

Fig. 6.1.2. Beam fabrication details (based on AISC specifications)

69

DETAILING OF MAJOR COMPONENTS

Fig. 6.1.3. End plate shear connections of wide flange beams—boltedand welded connections (based on AISC specifications)

70


Fig. 6.1.4. Bolted framed beam connection: (a) semi-rigid connection; (b) moment connection(based on AISC/LRFD specifications)

71


Fig. 6.1.5. Sloped and canted beam connections (based on AISC/LRFDspecifications)

72


Fig. 6.1.6. Web reinforcement of coped beams (based on AISC/LRFDspecifications)

73


Fig. 6.1.7. Sloping beam connections using Saxe seats (based on AISC specifications). Figure usedwith permission of The Lincoln Electric Company

74


Fig. 6.1.8. Miscellaneous connections assembled with Saxe seats andclips (based on AISC specifications). Figure used with permission of TheLincoln Electric Company

75


Fig. 6.1.9. Flexible and rigid connections: (a) beam–seat connections—flexible; (b) beam-to-column flange connections—moment-resistant;(c) beam-to-column web connections—moment-resistant (based onAISC/LRFD specifications)

76


Fig. 6.1.10. Beam–column welded and bolted connections: (a) weldedconnections; (b) bolted connections (based on AISC/LRFD specifica-tions)

77


Fig. 6.1.11. Beam–column seated and spliced connections: (a) endbeam to column welded connection; (b) beam–column connection withsplice beam connection (field/shop welding) (based on EC3 specifica-tions)

78


Fig

.6.1

.12.

En

d b

eam

–co

lum

n c

on

nec

tio

n—

pro

ject

ed v

iew

s (b

ased

on

BS

5950

sp

ecifi

cati

on

s)

79


6.1A. Detailing of welded plate girders

Fig. 6.1.13. Spandrel beam to columns (based on BS 5950 specifications)

80


Fig. 6.1.13. Continued

81


Fig. 6.1.14. Beam to column connection—all welds 6–8 mm (based on EC3 specifications)

82


Fig. 6.1.15. Sample shop detail drawing—beams (based on AISC specifications)

83


Fig

.6.1

.16.

Det

ailin

g o

f ty

pic

al b

eam

wit

h b

olt

ed a

ng

le c

leat

s: a

ll b

olt

s ar

e H

D20

gra

de

4.6;

th

e b

eam

is

S27

5; a

ll an

gle

s/ch

ann

els

S27

5 (b

ased

on

EC

3sp

ecifi

cati

on

s)

84


Fig

.6.1

.17.

Su

mm

ary

of

pla

te g

ird

ers

—b

rid

ge

(AW

S a

nd

AA

SH

TO

sp

ecifi

cati

on

s)

85


Fig

.6.1

.18.

Su

mm

ary

of

pla

te g

ird

ers

—b

uild

ing

(A

ISC

an

d A

WS

sp

ecifi

cati

on

s)

86


Fig. 6.1.19. Plate girders (symmetrical flanges), welded (based onBS 5950 specifications)

87


Fig. 6.1.20. Beam splice details over supports (continuous over threespans) (based on AISC and AASHTO specifications). From StandardSpecification for Highway Bridges, Copyright 1996, by the AmericanAssociation of State Highway and Transportation Officials, Washington,D.C. Used by permission

88


6.2. Columns and portal frames

Fig. 6.2.1. Types of column, holding down bolts and gantry girders (BS 5950 specification)

89


W column splices

Two cases are described below, namely splice plates shop welded and field bolted and shop weldedand field welded.

First caseFlange plates shop welded, field boltedDepth DU and DL nominally the same

Case 1

DL=(DU+ 14) to (DU+ 5

8)No fills.Furnish sufficient 21

2 �18 strip shims to

obtain 0 to 116 clearance on each side.

*Splice plates, welds and fasteners:

(1) Select width of splice plate, number and gage offasteners, and length LU in accordance with uppershaft size.

(2) Select thickness of splice plates, size A andlengths (X and Y ) of welds and lengths LL inaccordance with lower shaft size.

(3) Add LU+LL to obtain length of splice plates.

Case 2

DL=(DU �14)

DL=(DU �18)

DL=DU

DL=(DU+ 18)

Fills on lower shaft.


Same as for Case 1, except use weld size (A+t) onlower shaft.

FILLS (shop welded under splice plates):Fill thickness t:

Where DL=(DU �14), use 3

16

DL=(DU �18), use 3

16

DL=DU, use 18DL=(DU+ 1

8), use 18Fill width: same as splice plate.Fill length: (LL �2)

Case 3

DL=(DU+ 34) and over.

Fills on upper shaft, minimum welds.


Same as for Case 1.

FILLS (shop welded to upper shaft):Fill thickness t: 1

2(DL �DU )�18 or �

316, whichever results

in 18-in. multiples of fill thickness.Weld size B:

Weld length: (LU �14)

Fill width: Width of splice plateFill length: (LU �

14)

Second caseFlange plates shop and field weldedDepth DU nominally 2 in. less than depth DL

Case 4

Fills on upper shaft, developed for bearing.Fill width less than upper shaft flange

width.

*Splice plates and splice welds:

Same as Case 1.

FILLS (shop welded to upper shaft):Fill thickness: t: 1

2(DL �DU )�116

Weld size B:

Max.: 516 (preferred) or (t�

116) or t,

Weld length LB � (Af fp )/2fR � (L/2+112) in which

Af=finished contact area of one fill, fR=allowableshear value of one linear inch of weld, size B, andfp=computed bearing stress in fill

Fill widthMin.: (Splice plate width)+2NMax.: (Upper shaft fig. width)�2M

Fill length: LB

Case 5

Fills on upper shaft, developed for bearing.Fill width greater than upper shaft flange

width.Use Case 5 only when spaces M and N,

Case 4, are inadequate for welds B andA, or when fills must be widened toobtain additional bearing area.

*Splice plates and splice welds:

Same as Case 1.

FILLS (shop welded to upper shaft):Fill thickness: 1

2(DL �DU )�116

Weld size B:

Max.: 516 (preferred) or (TU �

116) or TU .

Weld length LB : Same as Case 4Fill width: (Splice plate width)+2N, or (Upper shaft

figure width)+2MRound greater value up to next quarter inch.

Fill length: LB

Note:1. *Min. AISC, ASD and LRFD specification.2. 1 inch=25.4 mm.3. If LB=fill length is excessive place weld size B across and offill and reduce LB by 1

2 or to L/2+112.

Disregard return welds in Case 2.

Fig. 6.2.2A. W column splice construction examples

90


Fig. 6.2.2B. Miscellaneous column splices—projected view (AISCspecification)

91


Fig. 6.2.3. Built up compression members—projected view (AISCspecification)

92


Splice Plate Fasteners Welds

Column Size Length No. LengthWidth Thk. of Gage Size

LU LL Rows G A X Y

W14�455 & over 14 58 121

4 9 3 1112

12 5 7

W14�311 to 426 12 58 121

4 8 3 912

12 4 6

W14�211 to 283 12 12 121

4 8 3 912

38 4 6

W14�90 to 193 12 38 91

4 8 2 912

516 4 6

W14�61 to 82 8 38 91

4 8 2 512

516 3 6

W14�43 to 53 6 516 91

4 7 2 312

14 2 5

W12�120 to 336 8 12 91

4 8 2 512

38 4 6

W12�53 to 106 8 38 91

4 8 2 512

516 3 6

W12�40 to 50 6 516 91

4 7 2 312

14 2 5

W10�49 to 112 8 38 91

4 8 2 512

516 3 6

W10�33 to 45 6 516 91

4 7 2 312

14 2 5

W8�31 to 67 6 38 91

4 7 2 312

516 2 5

W8�24 & 28 5 516 91

4 6 2 312

14 2 4

Gages shown may be modified if necessary to accommodate fittings elsewhere on the columns.

Fig. 6.2.4. Column member splices (based on AISC/ASD specifications, adapted by LRFD)

93


Fig. 6.2.5. Column splice fabrication details (based on AISC/LRFD specifications). Figure used withpermission of The Lincoln Electric Company

94


Fig. 6.2.6. Column bases (based on EC3 specifications)

95


Fig. 6.2.7. Miscellaneous column base details (based on AISC and EC3specifications). Figure used with permission of The Lincoln ElectricCompany

96


Fig. 6.2.8. Miscellaneous column base details (based on AISC/BS 5950specifications)

97


Fig. 6.2.9. Column base details (based on AISC and EC3 specifications)

98


Fig. 6.2.10. Multi-storey building column: (a) column schedule; (b) key plan grid (based on BS 5950and EC3 specifications); (c) detailing

99


Fig. 6.2.11. Column detailing practice—trussed column (based on BS 5950 and EC3 specifications)

100


Fig. 6.2.12. Design details of portal frames and projections (based on BS 5950 specifications): (a)–(c)isomeric views; (d) sectional elevation

101


Fig. 6.2.13. Structural details of portal frames (based on BS 5950 and EC3 specifications)

Fig. 6.2.14. Pre-set of portal frames—fabrication drawing (based on BS 5950 and EC3 specifica-tions)

102


Fig

.6.2

.15.

Co

mp

ute

r-ai

ded

str

uct

ura

l det

ails

of

po

rtal

fra

mes

—M

aste

rSer

ies

(bas

ed o

n B

S59

50 s

pec

ifica

tio

ns)

103


6.3. Trusses, lattice girders and trussed frames

Fig. 6.3.1. Types of truss and lattice girder and truss joints—isometricviews

104


Fig. 6.3.2. Chord and bracing sections and details (based on BS 5950,EC3 and AISC specifications)

105


Fig. 6.3.3. Node points—bolted construction (based on BS 5950 andEC3 specifications)

106


Fig

.6.3

.4.

Det

ailin

g o

f b

olt

ed t

russ

(b

ased

on

EC

3 sp

ecifi

cati

on

s)

107


Fig. 6.3.5. Node points—welded construction of an arched truss (based on Lincoln Electric Co.specifications). Figure used with permission of The Lincoln Electric Company

108


Fig. 6.3.6. Typical roof truss and details (based on AISC and Lincoln Electric Co. specifications).Figure used with permission of The Lincoln Electric Company

109


Fig. 6.3.7. Welded truss and details (based on AISC and Lincoln Electric Co. specifications). Figureused with permission of The Lincoln Electric Company

110


Fig

.6.3

.8.

Det

ailin

g o

f a

bo

lted

ro

of

gir

der

(b

ased

on

EC

3 sp

ecifi

cati

on

s)

111


6.4. Welded tubular steel construction

Fig. 6.4.1. Welded tubular steel construction (based on Lincoln ElectricCo.). Figure used with permission of The Lincoln Electric Company

112


chapter 6 design detailing of major steel components

Documents