Steel Design Misan University Fourth Year Engineering College Dr.Abbas Oda Dawood Civil Department

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BOLTED CONNECTION

1. INTRODUCTION

Steel Design Misan University Fourth Year Engineering College Dr.Abbas Oda Dawood Civil Department

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2- BOLTED SHEAR CONNECTION

2-1 Shear Failure of Bolts

Steel Design Misan University Fourth Year Engineering College Dr.Abbas Oda Dawood Civil Department

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2-2 Bearing Failure At The Bolt Hole

Steel Design Misan University Fourth Year Engineering College Dr.Abbas Oda Dawood Civil Department

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Steel Design Misan University Fourth Year Engineering College Dr.Abbas Oda Dawood Civil Department

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3-DESIGN PROVISIONS FOR BOLTED SHEAR CONNECTIONS

Steel Design Misan University Fourth Year Engineering College Dr.Abbas Oda Dawood Civil Department

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Determine whether the connection shown in Figure is adequate to support the applied

loads; consider the strength of the bolts in shear and bearing on the plate. The plates

are ASTM A36 and the bolts are 3⁄4-in.-diameter A325N in standard holes.

Solution

Check Shear on the bolts

bnn AFR

N325Aforksi48Fn

22b in442.0)4/3(

4A

bolt/kips9.15442.0*48*75.0Rn

Total shear strength of bolts group OKkips606.639.15*4Rn

Check bolt bearing

in06.18

1

4

35.05.1L 1c

in13.28

1

4

33L 2c

- For Bolt 1: in5.1d2in06.1L b1c

kips6.3458*625.0*06.1*2.1*75.0R

FtL2.1R

n

ucn

- For Bolt 2: in5.1d2in13.2L b2c

kips9.4858*625.0*75.0*4.2*75.0R

Ftd4.2R

n

ubn

Total bearing strength

OKkips601679.48*26.34*2Rn

Example 1

Steel Design Misan University Fourth Year Engineering College Dr.Abbas Oda Dawood Civil Department

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Example 2:For the splice connection shown in Figure, determine the maximum factored

load, P , that can be applied; consider the strength of the bolts only. The plates are ASTM

A36 and the bolts are 1-in.-diameter A325X in standard holes.

Solution

Check Shear on the bolts

bnn AFR

X325Aforksi60Fn

22b in785.0)1(

4A

bolt/kips3.35785.0*60*75.0Rn

Total shear strength of bolts group kips4243.35*62Rn

Check bolt bearing on outside plates

in43.18

115.02L 1c

in87.18

113LL 3c2c

- For Bolt 1: in2d2in43.1L b1c

kips5.3758*5.0*43.1*2.1*75.0R

FtL2.1R

n

ucn

Steel Design Misan University Fourth Year Engineering College Dr.Abbas Oda Dawood Civil Department

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- For Bolt 2and 3: in2d2in87.1L b2c

kips8.4858*5.0*87.1*2.1*75.0R

FtL2.1R

n

ucn

Total bearing strength on outside plates kips5408.48*85.37*4Rn

Check bolt bearing on inside plate

in93.18

115.05.2L 1c

in87.18

113LL 3c2c

- For Bolt 1: in2d2in93.1L b1c

kips5.7558*75.0*93.1*2.1*75.0R

FtL2.1R

n

ucn

- For Bolt 2and 3: in2d2in87.1L b2c

kips2.7358*75.0*87.1*2.1*75.0R

FtL2.1R

n

ucn

Total bearing strength on outside plates kips4432.73*45.75*2Rn

Thus Shear on the bolts controls the design

kips424Pu

Steel Design Misan University Fourth Year Engineering College Dr.Abbas Oda Dawood Civil Department

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4- DESIGN OF BOLTED CONNECTIONS AND AISC DESIGN TABLES

Table 7-1

Tables 7-5 and 7-6

Steel Design Misan University Fourth Year Engineering College Dr.Abbas Oda Dawood Civil Department

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Steel Design Misan University Fourth Year Engineering College Dr.Abbas Oda Dawood Civil Department

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Example 3: A 5⁄8-inch-thick tension member is connected to two 1⁄4-inch splice plates,

as shown in Figure. The loads shown are service loads. A36 steel and 5⁄8-inch diameter,

A325 bolts will be used. How many bolts are required? Each bolt centerline shown

represents a row of bolts in the direction of the width of the plates.

Solution

Bolts are in double shear. From Manual Table 7-1 for A325 and Double shear 5/8" X bolts

bolt/kips1.22rn

Assume that shear controls and then check bearing. The required strength of the connection is

kips7625*6.130*2.1L6.1D2.1Pu

44.31.22

76

boltperStrength

strengthquiredReboltsofNumber

Try four bolts, two per line, on each side of the splice. Check Bearing: The bearing force on the 5⁄8-inch-thick tension member will be twice as large as the bearing force on each of the 1⁄4-inch splice plates. 1- 1⁄4-inch splice plates -For the inner holes and a spacing of 3 inches, Manual Table 7-4 gives for STD bolts

325.164

1*3.65t3.65rn

-For the holes nearest the edge of the plate, we will conservatively use an edge distance of 1.25 inches to find the bearing strength from Manual Table 7-6.

825.114

1*3.47t3.47rn

Total strength on splice plates OKkips766.112825.11*4325.16*4Rn

1- 5⁄8-inch-thick tension member -For the inner holes

8125.408

5*3.65t3.65rn

-For the holes nearest the edge of the plate conservatively use an edge distance of 1.25

56.298

5*3.47t3.47rn

Total strength on splice plates OKkips7675.14056.29*28125.40*2Rn

Use four bolts 5/8", two per line, on each side of the splice.