1. Sanjivani Rural Education Society's
Sanjivani College of Engineering, Kopargaon 423603.
-Department of Civil Engineering-
By
Mr. Sudhir B. Gayake (Assistant Professor)
Mail Id- gayakesudhircivil@sanjivani.org.in
2. Prof. Sudhir B. Gayake, SCOE Kopargaon
Introduction to Connections-
§ A steel structure is an assemblage of different element, which are connected,
fastened to one other so as to act together.
§ Connections acting as a medium for transfer of force, load or moment from one
member to other.
§ The standard rolled sections has fixed length (Usually 13 Meter) which may be lesser
than site requirements.
§ Every element of structure is oriented in different directions and are to connected so
as to act as single composite unit.
§ The following types of connections:
1. Riveted connections
2. Bolted connections
3. Welded connections
4. Pins connections
5. Combination of above
3. Prof. Sudhir B. Gayake, SCOE Kopargaon
Bolted Connections-
§ A bolt may be defined as a metal pin with a
head at one end and a shank (body) threaded
at the other end to receive a nut.
§ Steel washers are provided under the
bolt as well as nut for; distributing the
clamping pressure of the bolted member
and to prevent threaded portion of the
bolt from the bearing on the connecting pieces.
Source:https://www.mechanicalbooster.com/wpconte
nt/uploads/2016/11/what-is-bolt.jpg
4. Prof. Sudhir B. Gayake, SCOE Kopargaon
Classification of Bolted Connections-
1) Based on force transferred:
a) Concentric connections- load passes through C.G.(Butt Joint)
b) Eccentric- load away from the C.G.(Lap joint)
c) Moment resisting connections- joint subjected to moment(Beam and column or
Bracket)
2) Based on type of force:
a) Shear connections- lap and butt joint
b) Tension connections- hanger connection.
c) Combined shear and tension- bracing.
3) Based on force mechanism:
a) Bearing type- bolt bear against the hole to transfer the force.
b) Friction type- force is transferred by friction.
5. Prof. Sudhir B. Gayake, SCOE Kopargaon
Types of Bolts-
1) Unfinished or black bolt-
Bearing type of bolt. It also called as
ordinary, common, rough bolt.Made from mild
steel rods with square or hexagonal head.
Nominal diameter(mm)- 12, 16, 20, 24, 30
and 36 are commonly used.
2) High strength bolts-
Made from medium carbon heat treated
steel and from alloy steel.
Has high strength two or more times than ordinary bolt.
Available in size diameter(mm)-16 to 36.
Soure:https://sc01.alicdn.com/kf/HTB1hFXMOVX
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Source:https://lh3.googleusercontent.com/proxy/etimEWOzma8cDTQqnBEhlI3ich1Erg-
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6. Prof. Sudhir B. Gayake, SCOE Kopargaon
Grade and designation of bolts-
qGrade 4.6 – M20
q20mm is diameter of bolt
qUltimate tensile strength = 4x100, fub = 400 N/mm2
qYield stress = 400x0.6, fyb = 240 N/mm2
qIS 1367 (part – 3)
Advantages:
1) Connections can be made quickly; erection of the structure speedy.
2) Less skilled persons are required.
3) Less equipment are required.
4) Cost is less.
Grade of
steel
fub fyb
3.6 330 180
4.6 400 240
4.8 420 320
5.6 500 300
5.8 520 400
7. Prof. Sudhir B. Gayake, SCOE Kopargaon
Types of Bolted Connections-
1) Lap joint-
Two member are overlapped
and connected together.
It may be single or
double bolted lap joint.
2) Butt joint-
Two member to be connected
are placed end to end.
Additional plates are provided
on either or one side is
known as cover plates.
8. Prof. Sudhir B. Gayake, SCOE Kopargaon
Failure of bolted joints- Failure may occure in bolts or member connected.
1) Shearing failure of bolt-
The maximum factored shear force
in the bolt may exceed the nominal
shear capacity of the bolt.
Bolt may fail in single or double shear.
2) Bearing failure of plates/Bolt-
When member is subjected to shear
force , slip takes place and bolt comes in
contact with plates.
3) Tearing of plate/Bolt-
It occures when bolts are stronger
than plate.
Bolt may fail at stressed area when
apllied tension is high.
9. Prof. Sudhir B. Gayake, SCOE Kopargaon
Specification for bolted Connections- (Cl.No. 10.2 Pg.No73 IS 800:2007)
1) Clearances for holes for fasteners(Table 19 Pg.No73 IS 800:2007) -
Source:https://www.nmri.go.jp/oldpages/eng/khirata/metalw
ork/basic/bolt/hole_e.jpg
10. Prof. Sudhir B. Gayake, SCOE Kopargaon
2) Pitch of the bolts (P)- (Cl. No. 10.2.2, page no. 73 IS 800:2007)
The distance between centers of two consecutive
bolts in row, measured along the direction of load.
P shall not be less than 2.5 times diameter of bolt.
P shall not be exceed 16t or 200mm, whichever is less (tension member)
P shall not be exceed 12t or 200mm, whichever is less (compression member)
P shall not be exceed 4.5 d, for butt joint.
3) Gauge distance (g)-
c/c distance of consecutive bolt of adjacent rows
and measured perpendicular to direction of load.
g shall not be exceed 100 + 4t or 200mm,
whichever is less.
g shall not be less than 2.5 of dh.
11. Prof. Sudhir B. Gayake, SCOE Kopargaon
4) End or Edge distance (e)-(Cl. No. 10.2.4.2, page no. 74)
It is the distance of center of bolt from adjacent edge of plate.
e shall not be less than 1.7 times diameter of hole………for hand flame edge.
e shall not be less than 1.5 times diameter of hole………for machine flame edge.
e shall not be exceed 12t t= thickness of thinner plate
e shall not be exceed 40 + 4t
