column splicing

7/28/2019 Column Splicing

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UNIT 8 DESIGN OF COLUMN SPLICESStructure

8.1 IntroductionObjectives

8.2 Splicing of Columns8.3 Design Elements of Splice Plate8.3.1 Design Steps for Column Splice

8.3.2 Design Problems on Column Splice8.4 Beam-Column Joints

8.4.1 Design of Framed Conneclion8.4.2 Design Example on the Framed Connection8.4.3 Design of Unstiffened Conneclion8.4.4 Design Example on Unstiffened Seated Connection8.4.5 Cesign of Stiffened Sealed Conneclions8.4.6 Design Example on Stiffened Seated Conneclion8.4.7 Design of Clip-angle Connection8.4.8 Design Example on Clip Angle Connection

8.5 Summary8.6 Answers to SAQs

8.1 INTRODUCTIONSometimes the length of a column in a multistoreyed building may be so large thatit cannot be manufactured out of a single piece. Hence splicing is frequently beresorted to in such cases. As this is a common point of weakness, this must beproperly attended to, so that a splice is not weak in axial load, horizontal shear orbending moment. The splices may be done by means of rivets or welds. These areexplained in this unit.In case of beams joining into a column a large variety of cases may arisedepending upon the shape and size of the joining members. These connections areagain to be properly made to develop the requisite resistance to shear, bearing,crushing, bending (moment) or torsion. Again the principal fasteners are eitherwelds or rivets.These connections are made by means of cleat angles, clip-angles,plates and seats or by simple framing. These have been extensively discussed inthis unit.ObjectivesAfter studying this unit you should be able todesign splices in column to column connections,design beam-column joints of various types,distinguish between stiffened and un-stiffened seated connection, anddesign cleat angle connection.

8.2 SPLICING OF COLUMNSColumns are the structural members used to take compressive loads. The splicingof a column is necessary where (a) the available length is less than the requiredlength or (b) the section is to be changed as per requirement.The beams are connected to the columns at their ends with the flange or web ofthe columns. The connection may be framed connections, seated connections


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Members in Flexure &Column Bases unstiffened or stiffened, or moment resistant connections. The connections may beriveted or welded.The necessity of column splicing is given is Section 8.2. The splicing should bedone 30 to 50 cm above the floor level to make section easy. The splicing shouldbe desi.gned to carry all types of loads i.e., axial loads, transverse force (horizontalshear) or moments.Typical column splices are shown in Figure 8.1.

PLicePlate

Figure 8.1: Type of Column Splices


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8.2.1 IS Code SpecificationsClause 5.3.4 of IS: 800-1984 gives the specifications for column splices. These are:

1) a) Where the ends of compression members are faced for bearing overthe whole area, they shall be spliced to hold the connectedmembers accurately in position, and to resist any tension whenbending is present.b) The ends of compression members faced for bearing shallinvariably be machined to ensure perfect contact of surfaces in

bearing.2) Where such members are not faced for complete bearing, the splicesshall be designed to transmit all the forces to which they are subjected.3) Wherever possible, splices shall be proportioned and arranged so that thecentroidal axis of the splice coincides as nearly as possible with thecentroidal axes of the members jointed in order to avoid eccentricity, but

where ec centricity is present in the joint, the resulting stress shall beprovided for.SAQ 11) What is columns splicing?

2) What is the necessity of column splicing?3) What are types of connections used for beam with columns?

8.3 DESIGN ELEMENTS OF SPLICE' PLATE1) W idth of splice plate2) Length of splice plate3) Thic knes s of splice plate4) No. of rivets

83.1 Design Steps for Column SpliceCase 1: For uniform column section, the ends of the column are cut by ordinarymethod and are not milled.Steps

1) Load to be transmitted by column splices = total axial load.12) Load taken by one splice plate =- total axial load.2

3) Assume oa,= 150~ / r n r n ~ ,ince the slenderness ratio is zero because thesplice plate is in contact with column.

4) Calculate the area of splice plate required.Load on splice plateArea of splice plate = 150

5) The width of splice plate = width of flange of column.


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Members in Flexure &Column Bases 6 ) Calculate the thickness of plate required- Area of splice platewidth of sp lice plate 'Minimum thickness should be 6 mm.

7 ) Assume the diameter of rivet and calculate the gross diameter of rivets.8) Calculate the strength of rivets in single shear and bearing. Find the rivetvalue.9) Calculate the number of rivets ( n )

Land on splice plate: n = Rivet valueAdopt in 'n ' number of rivets on either side of the joint.

10) Calculate the length of the splice plate= 2 x edge distance + (n - 1 ) pitch.Minimum pitch = 2. 5 x nominal diameterEdge distance = 1.5 x nominal diameterCase 2: For uniform column section, the ends of the column are machined andmilled.

Steps1 ) Load to be transmitted by column splices = 50% of total axial load.

Follow the same step ( 2 ) to ( 1 0 ) as in case ( 1 ) .Case 3: For uniform column section subjected to axial load and moment.Steps

moment1 ) Additional axial load due to moment = depth of column sect ion2 ) Follow the steps ( 1 ) to ( 1 0 ) given in case ( 1 ) .

Case 4: Splicing of different column sections subjected to axial force, moment andshear.a) Whe n the difference in column depths is less, no bearing plate is required.

1 ) Design of Filler Plate1For flanges, the thickness of filler plate =- difference of column2

depths.The width of filler plate = It gradually decreases from width of flange oflower column to the width of flange of top column.

1Length of filler plate 2 - length of flange splice plate.2For Webs, Size of filler plate = size of web plate.

1Thickness of filler plate = - difference in thickness of webs.22 ) Design of Flange Splice Plate

It is used to resist axial force and moment.The design procedure is same as case (3).


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Design of Web PlateLet us adopt 2 rivets on either side of joints. Calculate the rivet value.

HCalculate the force due to axial force, Fa=-2 '

Figure 8.2: Web PlateM .rCalculate the force due to moment, F,- = ( H x a ) .z ?Calculate the resultant force on the rivet. F = It should be less

than the Rivet value. If not change the diameter. Calculate the thickness ofHweb plate =-7 v a

2where, zva= 100N/mm .b) When the difference in column depths ismore, bearing plate is required.

Design of Bearing PlateMoment M = x b .2Width of Bearing Plate

= width of flanges = 1 .

Design of Column Splice

The design of flange splice plate, web Figure 8.3: Bearing Platesplice plate and filler plate is similar to case (4).

9

8.3.2 Design Problems on Column Splices

- uppe r CoLuliln

Example 8.1A column consisting of ISHB 400 @ 822 N/m carries an axial load of400 kN. Design the colume splices when

+

54 Lower

c b - y

.


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Members in Flexure &Column lasea a) The ends of the column are cut by ordinary methodb) The ends of the columns are milled and faced for bearing.Take f, = 250 Nlmm2.

Solutiona) The ends of the columns are cut by ordinary method.

1) Load to be transmitted by column splices = Total axial load = 400 kN .4002) Load on each splice =- 200 kN23) Assume oa,= 150N/mm2

4) Area of splice plate = 200 lo3150 = 1333.32mm2.5 ) Width of splice plate = width of flange = 250 mm.6) Thickness of splice plate = 1333'33= 5.33mm. Adopt 6 mm thickness.2507) Let us use 20 mm diameter power driven shop rivets.

Gross diameter = (20+ 1.5)= 2 1.5mm .8) Strength of rivets in

300ii) Bearing = 21.5 x 6 x- 38.7 k N1000; Rivet value, R = 36.3 kN.

2009) No. of rivets =- 5.536.3Use 6 rivets in two rows of 3 each on either side of the joint.10) Let pitch = 60 mm.

Edge distance = 30 mmLength of the plate = 5 x 60 + 2 x 30 = 360 mm

(a) (b) 'Figure 8.4


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b) The ends of the column s are milled and faced for bearing1) Load on column splices =-00 - 200kN.22) Load on each splice =200= 100kN .23) Assume o,, = 150N md.4) Area of splice plate = loo lo3= 666.67mm2.1505 ) Width of splice plate = 250 mm.

666.676) Thickness of splice plate =----- -250 -2.67mm .Adopt 6 mm thickness.

7) Let us use 20 mm diameter power driven shop rivets8) Rivet value, R = 36.3 kN.9) No. of rivets =-oo - 2.8. Use 4 rivets is two rows on either side of36.3the joint10) Let pitch = 60 mm.

Edge distance = 30 mm.Length of the plate = 3 x 60+ 2 x 30=240mm.

( 0 )Figure 8 5 6,

Example 8.2A column consisting of ISHB 400 O 822 N/mm carries an axial load of400 kN and a moment of 20 kN-m. Design the column splices when the endsof the column are milled and faced for bearing.

Solution1) Depth of the column section, d = 400 mm.

Design of Column Splices


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Members in Flexure &Column Bases M 20Additional axial load due to Monlent =- - 50 kN.d 0.42) Total axial load = 40 0 + 50 = 450 kN

4503) Load on column splices =- 225 kN.24) Load on each column splice = E =12.5 kN.25 ) Assume o,, = 150 N mm 26) Area of splice plate 112.5 x lo3 2150 = 750 mm .7 ) Width of splice plate = 250 mm.

7508) Thickness of splice plate = -- = 3 mm.25 0Adopt 6 mm thickness.

9) Let us use 20 mm dia. P.D.S. rivets10) Rivet value, R = 36.3 mrn.

112.536 3 - 3.11) No of rivets, n = -----

Adopt 4 rivets in two rows of two each on either side of the joint12) Let pitch = 60 mm

Edge distance = 30 mm.Length of the plate = 3 x 60 + 2 x 30 = 240 mm.

(a) Figure 8.6Example 8.3

A column consisting of ISHB 400 @ 822 N/m carries an axial load of400 kN, moment of 20 kN and shear force of 40 kN. Design the columnsplices where the ends of the column are milled and faced for bearing.Solution

Take f, = 250 ~ l m m ~ .Desig n jlange splice plate


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Design of We b Splice Plate1) Shear force = 40 kN

Average shear stress = 0.4 f , = 100 ~ / m m ~2) Assume thickness = 6 mm.3) Area of web plates = 40 lo3= 400 mmz100

400 2Area of one web plate =- 2 0 0 m m .2 2004) Length of the web plate required =-6 - 33.33 mm.Let us adopt 120 mm length plate. Width 120 mm.

5 ) Let us adopt 4 rivets of 20 mm dia p.d.s rivets6) Streng th of rivets in

n:i) double shear = 2 q (21 .5d) x = 72.6 kN1000300ii) bearing = 21.5 x 6 x- 38.7 kN .1000: Rivet value, R = 38.7 kN7) Check for RivetsThe rivets are subjected to eccentricity of force. The rivets are underdirect force and force due to moment.


Figure 8.8


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Members In Flexure &Cotmnn~Base

Resultant force on rivet ==m=2.4 k~ < Rivet value (OK )

Example 8.4Design a suitable splice joint between the bottom column ISHB 250 @ 54 7N/m and the top column ISHB 225 @ 468 N/m. At the joint, the column issubjected to an axial load of 400 kN, a moment of 25 kN-m and a shearforce of 40 kN. The ends of the columns are fully faced for complete bearing.Take fy = 250 ~ / m m ~ .

SolutionDesign of Flange Splice Plate1) Thickness of filler plateDepth of ISHB 250 = 250 mm

Depth of ISHB 225 = 225 mmThickness of filler plate = 25 0 - 22 52 = 12.5mm.Since the difference is less, no bearing plate is required.Width of filler plate = 225 mm.

2) Axial load = 400 kNDepth of the section, d = 250 mm.

25 - 1 0 0 k N .dditional axial load =- -d 0.25Total axial load = 400 + 100 = 500 kN.'0 - 250 kN.) Load on splice plates =-2

4) Load on each splice plate =250 = 125 kN.2

5) Assume o,, = 150 ~ / m m ~6) Area of splice plate = 12' lo3 = 833.33 rnm21507) Width of splice plate = 250 mm.

833.338) Thickness of filler plate =- 3.33 mm250Adopt 6 mm thickness.

9) Let us use 20 mm dia. p.d.s rivets.10) Rivet value, R = 36.3 kN.


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125 - 3.441) No. of rivets, n =-36.4Use 4 rivets in two lines of two each on either side of the joint.

12) Using a pitch of 60 mm and edge distance of 30 mm.Length of the plate = 3 x 60 + 2 x 30 =240 m.A

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(a) Figure 8.9Design of Web Splice Plate

1) Thickness of filler platet, of ISHB 250 = 9.7 mmt , of ISHB 225 = 9.1 mm

Design of Coluron Splices

9.7- 9.1Thickness of filler plate = 2 =0.3 mm.2) Shear force = 40 kN

4) Area required = 40x id100 =400mrn24005) Area of one web plate =- 200 mm2.2

6) Assume thickness of web plate = 6 mm .2007) Length of web plate =- 33.33 mm.68) Let us adopt 4 rivets of 20 mm dia PDS rivets9) Let pitch = 60 mm, edge distance = 30 mm.

Width of plate = length of plate = 2 x 30+ 60= 120mm.10) Rivet value, R = 38.7 kN.11) Check for Rivets

Same as in Example 8.3Rivets for Filler Plates: Use 2 - 20 mm @ p.d.s rivets for filler plates.


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'Members in Flexure &Column Bases

C c - 2 5 0 d h ' O m d(a) (b)

Figure 8.10Example 8.5

A column of section ISHB 300 @ 630 N/m. Carrying an axial load of600 kN is supported over another column of section ISHB 400 @ 822 Nlm.Design the splicing at the joint. The ends are milled for full bearing.Take f, = 250 ~ l m m ~ .SolutionFiller Plate Design

Depth of ISHB 400 = 400 mm.Depth of ISHB 300 = 300 mm.Thickness of filler plate = 400 - 300 = 50 mm.2Width of filler plate = 250 mm.

Design of Bearing Plate


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Design of Column Splice

6)Design of

= 14.835 x lo6N - mmWidth of bearing plate 1 = 25 0 mm.

Thickness of bearing plateq c +zzzz7t = 1 obc 25 0 x 165

= 46.45 mm. Adopt 50 mm thicknessLength of the plate = 400 mm.

' Flange Splice Plate600Load on splice plate =- 300 kN.2

300 wZLoad on each splice plate =- 150 kN.2Width of splice plate = 250 mm.o,,= 150 ~ / m r n ~ -Area required = 150 lo) = mm2150Thickness =-ooo - 4 mm. Adopt 6 mm thickness250

Figure 8.12

----r

---------

I I I I

Rf2arcn$ Plate

I S H B kOO

*


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Members in Flexure &Column B w a 7) Let us use 20 mm dia. PDS rivets8 ) Rivet value, R = 36.3 kN.9 ) No of rivets =-- 50 -4.1336.3

Use 6 rivets of two rows of 3 for each on either side of the joint.10) Using a pitch of 60 rnrn and an edge distance of 3 0 mm

The length of plate = 5 x 60 + 2 x 30 + 5 0= 410 mm.Rivets for Connecting Filler Plates

As per code, for 8 mm thickness -2.5% of rivets2 5 50

\ For 50 mm thickness =- - 4.13 = 0.65100 8Adopt 2 rivets in two lines one for eachLength of filler plate =4 x 30 + 60 = 180 mm.

SAQ 21 ) A column consisting of ISHB 400 @ 774 Nlrn caries an axial load of700 k/N. Design the column splices, assuming that (a) ends of thecolumn are cut by ordinary method and not milled and (b) ends of thecolumns are milled and faced for bearing. Take f ,= 25 0 ~ / m m ' .

2) A column consisting of ISHB 350 @ 724 Nlrn subjected to a moment of70 kN-m in addition to an axial load of 500 kN. Design the columnsplices, if the ends are milled and faced for bearing. Take fy 250 ~ / r n r n ~ .

3) A column section ISHB 150 @ 271 Nlrn is to be spliced with anothercolumn section ISHB 150 @ 346 Nlrn. The load on the column is200 kN. Design the Splice.

4) A column section ISHB 450 @ 872 Nm is to be spliced with a columnISHB 300 @ 588 Nlrn. The load on the column is 500 kN. Design asuitable splice. If a shear force of 100 kN also acts, design the shearsplice.5 ) A column section ISHB 225 @ 468 Nlrn is to be spliced at floor level.The force at the section are axial load, transverse shear and bendingmoment of 300 kN, 80 kN, 22.5 kN-m. Design a suitable splice. ,6) A column section ISBH 400 @ 0.822 Nlrn is carrying an axial load of500 IcN (50t) and a Bending moment of 40 kN-m (4 t.m) as well asshear force of 60 kN (6t). Design the cloumn, the column splice andshear splice. Adopt IS 800-1984 specifications.7) A column ISHB 350 @ 674 Nlrn is carrying an axial load of 1000 kN.It is to be supported over a column section ISHB 450 @ 872 N. Designthe column splice. Draw to a suitable scale (1) sectional elevation (2)

End view.


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8.4 BEAM-COLUMN JOINTS Deslw'of Column S p l h,The beams are connected with columns by using rivets, pins or by welding. Thebeams may transmit vertical reaction or moment with vertical reaction. Theconnections may be simple Semi-rigid or Rigid. In simple connections rotationalrestraint is less. It is not used in practice. In practice Rigid connections are used.The connections in rivets may be

i) Framed connections (Figure 8.13)ii) Seated connections

a) Unstiffened seat connection (Figure 8-14)b) Stiffened seat connection (Figure 8.15)

iii) Mom ent resistant connectionsa) Clip angle connection (Figure 8.16)b) Bracket connections (Figure 8.17)c ) Split Beam connection (Figure 8.18)d) Modified split beam connection (Figure 8.19)

i) Framed ConnectionsA beam is connected to a column by using two angles on both sides of theweb of the beam.

Figure 8.13: Framed Beam Connections

*

ii) Seated Beam Connections

-Stanchion. *v -

In some cases the width of the flange or the depth of the web may beinsufficient to accommodate the connecting angles. In that case the seatedBeam connections are used.a) Unstiffened Seat Connections

A seat angle is used to receive the beam.The seat angle is the onewhich has horizontal leg to receive.It consists of flange cleat angle to keep the beam stable in a vertical position.

by Stiffened Seat ConnectionsIt consists of seat angles, flange cleat angles and stiffener angles. Thistype of connection is used when the reaction is to be transmitted is moresuch that the cleat angle does not bear it.


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I Members in Flexure &Column Bases

I

(b)Figure 8.14: Unstiffened Seated Connection

Figure 8.15: Stiffened Seated Connectioniii) Moment Resistant Connections

This type of connections transmit shear and moment. Based on the magnitudeof the moment to be transferred the connections may be 1.5 m all and 2 largemoment resistant connections.a) CLIP Angle Connections

In this connection 4 angles are used i.e. two clip angles and two web angles.Th e web angles resist shear only. The clip angles resist m oment only.


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(b)(a)

Figure 8.16: Clip Angle Connectionb) Bracket Connections

This connection is large moment resistant connection. It consists of twosets of angles along with gusset plates. One set is attached to the flangeof the column and the other set is connected to the flange of the beam.

Figure 8.17: Bracket Connectionc) Split Beam Connections

It is a large Moment Resistant connection. It consists of 2 split beamsprovided at the top and bottom flanges of the beam and two web angles.The split beams resist only moment, the web angles resist shear only

Design of Column Spllces


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M e m b n In FlexureCdumn Bases

Figure 8.18: Spit Beam Connectiond) Modified Split Beam Connection

It is a large moment resistant connection. It consists of two split beamstwo web angles and one or two flange clip seats. The flange clip seat iscommonly I-section.

Figure 8.19: Modified Split Beam Connection8.4.1 Design of Framed ConnectionData

1) Size of the column2) Size of the beam


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3) End reactionStep I : Design of Rivets

i) Assume the diameter of the Rivet.ii) Calculate the Gross diameter of the Rivet.

a) Rivets connectiong web angle with web of the beamCalculate the strength of rivets in double shear and bearing.Calculate the Rivet value.

End reactionCalculate the no. of Rivets = Rivet valueb) Rivets connecting the angle with flange of the column.

Calculate the strength of Rivets in single shear and Bearing.Calculate the Rivet value

End reactionsCalculate the no. of Rivets = Rivet valueStep 2: Size of the Angle

i) Size of the angle leg is decided by the no. of rows of Rivetsii ) The length of the angle depends upon the no. of rivets in a row and thedepth of the web of the beam.

1 Step 3: Thickness of the W eb Anglei) Calculate average shear stress n =0.44ii ) Calculate the thicknesss required

End reactionf = n , x 2 x hwhere, h = length of the web angle

8.4.2 Design Exam ple on Framed ConnectionA beam ISLB 400 @ 558 Nlm is supported at the flange of the column ISHB 250@ 537 Nlm. The beam cames an end reaction of 100 kN.Design a suitableframed connection.

1) Design of Rivets 'Let us provide 20 mm dia. power driven shop rivetsGross diameter = 20 + 1.5 = 21.5 mma) Rivets connection angle with web of beam

Strength of Rivets in71 loo -72.6kN) Double shear =2xax(21.3) x--1000

2) Bearing =21.5x8x-- 300 - 51.6k.N.loo0t , for ISLB 400 = 8 mmRivet value = 51.6 kN

Dedgn of Column Splka


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Members in Flexure & End reactionColumn ~ a f e s No. of Rivets n = Rivet value

= 2 (say)b) Rivets Connecting Angle with Flange of Column

Strength of Rivets in7C1) Single shear = - x (21.5)~ E = 36.3 kN1000

300 -51.6kN2) Bearing = 21.5 x 8 x --1000a Rivet value = 36.3 kN

End reactionNo of Rivets n = Rivet value

= 4 (say)Provide 2 rivets for each angle

2) Size of the AngleThe rivets are provided in a single low. Adopt ISA 90 x 90 angle.Adopting a pitch of 60 mm and an edge distance of 30 mm, the lengthof the angle required I

= 2 x 3 0 + 6 0= 120 mm

Figure 8.20


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Adopt 120 mm length angle3) Thickness of the Angle

Average shear stress nva= 0 . 4 4

End reactionThickness f = nva h

Adopt 8 mm thick angle8.4.3 Design of Unstiffened ConnectionThese are suitable upto an end reaction of 200 kN.Step I : Design of Seat Angle

a) Calculate length of seat angle = flange width of beamb) Calculate the bearing length (1)

where, V = ~ n deaction,op= permissible bearing stress (0.75 fy),tw = thickness of web of the beam, andh2 = from steel tables.= Root of fillet

Adopt the greater values of the above tw.c) Calculate the moment M = V. a

where, n = (4 10) but actual value of a is equal to (end clearance1+-- hickness of angle - oot radius)2 .

But, calculation take approximate value of a .rn rnd) Calculate Z required =- -.o,, 185

c) Calculate thickness of angle- 6 2- dLen gth of the angle


97


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Mcnbbers in & Step 2: Design of Rivets in Vertical LegsColu~nnRases a) Assum e diameter of rivetsb) Find gross diameter of rivetsc ) Calculate the strength of rivets in single shear and bearingd) Calculate the rivet value

End reactione) Calculate the number of rivets = Rivet valuef) Adopt the size of seat angle depending the no. of rivets and no. of rows

Step 3: Desigrz of Rivets Connecting Seat Angle with Bean?Provide two rivets.

Step 4: Rivets Connecting Cleat AnlgeAdopt two rivets for connecting cleat angle with beam and column also

Step 5: Size of Clea t AngleAdotp ISA 100 75, 8 mm with 100 mm leg horizontal

8.4.4 Design Example on Unstiffened Seated ConnectionA beam ISLB 400 @ 558 N/m is supported at the flange of the column ISHB25 0 @ 537 N/m. The beam carries an end reaction of 125 kN. Designunstiffened seated connection.

SolutionStep 1: Design of Seat Angle

a) Length of seat angle = flange width of beam = 165 mm.b) Bearing length ( 1 )

i) o, =0.7 f,= 0.75 x 25 0 = 187.5 ~ / m m 'tw= 8.0 mm.

= 28.08 mm.

Adopt 1 = 41.67 mm.


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e) t = 6 2dlength of the angle

Adopt 18 mm thick angle.Step 2: Rivets in Vertical Lega) Assume 20 mm. dia. rivets,b) Gross diameter = 20 + 1.5 = 21.5 mm.c) Strength of rivets in

71i) Single shear = - ( 2 1 . 5 ) ' x B = 36.3 kN4 1000300ii ) Bearing =2 1.5x 8x-= 51.6 kN.1000

d) Rivet value, R = 36.3 kN .125e) Number of rivets =- 3.44.36.3Adopt 4 rivets in two rows.Let us adopt ISA 200 150, 18 mm angle with 200 mm leg vertical.

Step 3: Rivets Connecting Seat Angle with beam.Provide 2-20 mm dia. rivets, one on each side of the web.

Step 4: Rivets Connecting Cleat AngleProvide 2-20 mm dia. rivets to connect cleat angle with beam and column also.

Step 5: Size of Cleat AngleAdopt ISA 10075, 8 mm size angle with 100 mm horizontal.

TOP dl-c lea t

' f

(a ) -250( b )

Figure 8.21Design bf Stiffened Seated Connections

Dcsign of Colun~nSplice

If the end reaction is more than 200 kN, hen


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Members in Flexure &Column Bases i ) the required thickness of seat angle is abnormal, and

ii) the length of leg of the seat angle is not sufficient to accommoda te therequired number of rivets. In this case, stiffened seated connections areused.Design ProcedureStep I : Design of Stiffeerzer Angle

a) Calculate the bearing length

vii) I= - 20, , , ,Adopt the maximum of the above two values.

b) Assuming a clearance of 10 mln, find the distance of stiffening edgefrom the flange of column = (1+ 10) rnm.vc ) Calculate the bearing area required =-OPArea requiredCalculate the stiffener angle = (1 + 10 )

e) Check the outstand of the stiffener angleMaximum outstand = 16 t.

Step 2: Design of Seating Anglea) Adopt ISA 130130, 10 mm seat angleb) Use 2-2 mm dia rivets for connecting with beam and column alsoC ) Length = flange width

Step 3: Design of Connectionsa) Calculate the a = distance of end reaction from the face of the column

1= (thickness of seat angle ) + (horizontal leg length of stiffener angle) --.2b) Calculate M , V.a (bending moment)c ) Calculate torsion m2 V.g

where, g = gauge distance.M z is only single s t i f h e r angles.

d) Calculate the rivet value, Ke ) Calculate the number of rivets,

where, m = no. of rows.p = pitch of rivets


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Step 4: Check for Stresses in Rivetsa) Calculate SF in each rivet ( F I )b) Calculate shear force due to M 2 ( F 2 )

C ) Calculate the resultant SF , F =rd) Calculate nv f l , =

e) Calculate 0% .,,= 6 M2r n ~ n * ~0~ ca l n v f c a ~f ) Calculate,- -lj n v f

It should be less than 1.40Step 5: Design Cleat Angle

a) Use ISA 100 75, 8 mm angle with 100 mm leg horizontal.b) Use 2 rivets for connection with beam and column also.

8.4.6 Design Example on Stiffened Seated ConnectionsA beam ISMB 400 transmits an end reaction of 250 kN to the flange ofISHB 300. Design the stiffened seat connection using one stiffener angle.

Solution1) Design of stiffener angle o,,= 0 . 7 5 4 = 187.5 MP a

h 2 6) i) I = - -o,, t w tw = 8.9 mm.

Adopt 93 mm bearing length.b) Assume end clearance = 10 mm.

Min. distance of stiffened edge from the column flange= 10 + 9 3 = 103 mm.

vc) Bearing area required =-d) Thickness required = 1333.3310 3 = 12.9mm

Adopt ISA 130 130, 15 mm as stiffener angle

Design of Cdumn Splices


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Members in Flexure & e) Maximum allowable outstand = 16 t = 16 x 15= 240 mm.Column BnsesOutstand = 130-15 = 115 mm < 240 mm (OK)

Step 2: Design of Seating Anglea) Adopt 1SA 150 150, 10 mm seat angle.b) Use 2-22 mm. dia, rivets for connecting with beam and column also.c) Length of angle = flange width of beam= 165 mrn.

Step 3: Desigrz of Conrzections

d) Using 22 mm dia power driven shop rivetsGross diameter = 22 + 1.5 = 23.5 mm.Strength of rivets in

ni ) Single shear =- 23.5)' x100 43.37k~4 1000300ii ) Bearing = 23.5x 10.6x- 74.73 kN1000

(thickness of flange = 10.6 mm). Rivet value, R = 43.37 kN .e) Number of rivets, rt =

= . 6 x 23375 let Y = 70 mm1x 70 x 43.37= 6.8

Adopt 8 rivets in a single rowStep 4: Check for Stresses in Rivets

= 36.75 kN. 11 + IL36 - 75 lo3= 84.74 Nj mm 2Z V J 01= (23.a2 Figure 8.23


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Let us adopt 10 rivets i n a single row

Design of Colutnn Splices

Not sa.f'&

Figure 8.23

Figure 8.24


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Members in Flexure &Column Bases

---110'76- 1.10< 1.40 Safe.100Step 5: Design of C leat Angle

a) Use ISA 10075, 8 mm angles with 100 mm leg horizontal.b) Use 2 rivets for connecting with beam and column.

8.4.7 Design of Clip Angle ConnectionData

Size of.beamSize of Column.End reaction and moment.

Step I : Culculation of Strength of RivetsAssume the diameter of rivets.Find the gross diameter.Calculate the strength of rivets ina) Single shearb) Double shearc) Bearing against web of beam.d) Bearing against flange of beam & column.e) Axial tension.

Step 2: Design of Clip Anglesa) Adopt 2 rivets for connecting the clip angle with column flange.b) Find the strength of 2 rivets.c) Calculate the minimum distance required between top and bottom rivets.- End momentStrength of rivetsd) Choose the suitable size of vertical leg of clip angle.e) Calculate the horizontal shear between clip angle and beam.

Horizontal shearf) Calculate No. of rivets = Rivet valueMinimum number of rivets is 4 for rigidity

g) Choose the size of horizontal legh) Calculate the moment in the clip. ( M I )

M , = 0.6 x pull in each rivet x g ( g - 60 mm)i) Calculate the thickness of clip angle


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r = Here, b = Rivet spacingDcsig11 of Colunlli Splices

j) Adopt the suitable clip angle.Srcp 3: Design of Web Atzgles

a) Adopt the size of web angles.b) Calculate the number of rivets for connecting with web of beam.c) Calculate the number of rivets for connecting with flange of beam.d) Adopting suitable pitch and edge distance, find the length of the angle.

8.4.8 Design Example on Clip Angle ConnectionAn ISMB 350 @ 524 N/m. transmits an end shear of 100 kN and a momentof 20 kN-m to the flange of column ISHB 350 @ 724 N/m.Design a suitable clip angle connection

SolutionData

V = 100 kN . M = 20 kN -m. For ISM B 350 @ 524 N/m.fJ.= 14 . 2m m r , = 8.1 m m . b = 140 mmFor ISHB 350 0 724 N/m.r f = 11.6 mm, b = 250 mm.g = 1 4 0 m m

Step I : Stretlgth of RivetsAssume 20 mm dia, P.D.S. rivets.Gross diameter = 2 0 + 1.5 = 21.5 mm.a) Strength of rivets in single shear

b) Strength of rivets in double shear = 2 X 36.3 kN .c) Strength of rivets in axial tension

d) Strength of rivets in bearings on 8.1 rnm300 - 52.25 kN.eb = 2 1 . 5 x 8 . 1 x--1000

e) Strength of rivets in bearing on 11.6 mm300Flange = 2 1.5 x 11.6 x ----= 74.82 kN.1000

f) Strength of rivets in bearing on 14.2 mm300 -91 . 59kN .lange = 21.5 x 14.2 x-1000


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Members in & Step 2: Design of Clip AnglesCahmn Basesa) Adopt 2 rivets for connecting the clip angle with column flangeb) Rivet value = 36.3 kN

(single shear, bearing against 11.6 mm thick plate)Strength of 2 rivets = 2 x 36.3= 72.6 kN

c) Minimum distance required between top and bottom rivets- End moment - 20 X 103- = 275.5 mm.Strength of rivets 72.6

But, the depth of beam is 250 mm.d) Hence adopt 100 mm vertical leg.e) Horizontal shear between clip angle a'nd

2 0 x 1 0 3 = 5 7 . 1 k ~eam =-d 350f) Rivet value = 36.3 kN.

(Single shear & bearing on 14.2 mm plate)57.1NO. of rivets, n =-6.3 - 1.57.

Adopt 4 rivetsg) Adopt 200 mm horizontal legh) Pull in two rivets = 20 lo3 =42.55 kN.(350 + 2 x 60)

42.55Pull in each rivet =- 21.28 kN.2

M , = 0.6 x pull in each rivets x g= 0 . 6 x 2 1 . 2 8 ~ 6 0= 766.08 kN - mm= 766.08 x lo3N -mm.

i) Thickness, t =

Use 15 mm thick angle.j) Adopt ISA 200, 150, 15 mm angle as clip angle

Step 3: Design of W e b A ngle sa) Adopt ISA 100, 100 m 8 rnm angleb) Rivets connecting web of beam Rivet value = 52.25 kN.

(Double shear & bearing on 8.1 mm plate)


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100 Design of Column SplicesNo. of rivets =- 252.25c) Rivets connecting column flange. (Single shear & bearing on 11.6 mm plate)

Rivet value = 36.3 kN100No. of rivets =- 3.36.3

Adopt 4 rivets.d) Adopting a pitch of 60 mm and an edge distance of 30 mm, length ofweb angle = 2 x 3 0 + 3 x 6 0 = 2 4 0 m m .

8.5 SUMMARYIn this unit you have studied the subject of splicing in long columns. As thecolumns in multi-storyed buildings are very long, they need frequent joining bymeans of splices. You have studied both the riveted and welded type of suchcolumn splices. The other important topics explained in this unit was that ofbeam-column connections. As they are generally right-angled connections and maylie in different planes these are effected by framing, the directing seating design ofall these connections have been explained in detailed in this unit.8.6 ANSWERS TO SAQsRefer the text and examples given in the unit.

column splicing

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