1. No category

UK
EUROCODES
Damascus University – Spring 2015
Instructor: Dr. Nachwan Khair
Lecture 4
Lecture 4
Tension connections
Lecture 4
Lecture 4
Tension connections
Bolted connection loaded in tension should be
designed as one of the following:
Category D: non-preloaded
In this category bolts from class 4.6 up to and including
class 10.9 should be used. No preloading is required. This
category should not be used where the connections are
frequently subjected to variations of tensile loading.
However, they may be used in connections designed to
resist normal wind loads.
Lecture 4
Tension connections
Bolted connection loaded in tension should be
designed as one of the following:
Category E: preloaded
In this category preloaded 8.8 and 10.9 bolts with
controlled tightening in conformity with 1.2.7 Reference
Standards: Group 7 should be used.
Lecture 4
Design resistance
Table 3.4 of EN 1993-1-8 lists the design rules for individual bolts subjected to shear and/or tension.
For tension the resistance is
Where
Lecture 4
Design resistance
Table 3.4 of EN 1993-1-8 lists the design rules for individual bolts subjected to shear and/or tension.
For combined shear and tension
the resistance is covered by the formula
Lecture 4
Design for block tearing
In addition, a new failure mode, block shear, has been
observed in a shear joint involving a group of bolts
Lecture 5
Design for block tearing
Block tearing consists of failure in shear at the row
of bolts along the shear face of the hole group
accompanied by tensile rupture along the line of
bolt holes on the tension face of the bolt group.
Figure 3.8 shows block tearing.
Lecture 4
Lecture 4
Design for block tearing
For a symmetric bolt group subject to concentric
loading the design block tearing resistance, Veff,1,Rd
is given by:
where:
Ant is net area subjected to tension;
Anv is net area subjected to shear.
Lecture 4
Design for block tearing
For a bolt group subject to eccentric loading the
design block shear tearing resistance Veff,2,Rd is
given by:
Lecture 4
Eccentric connections
There are two principal types of eccentrically loaded connections:
1. Bolt group in direct shear and torsion; and
2. Bolt group in direct shear and tension.
1.
2.
Lecture 5
1. Bolt group in direct shear and torsion
the moment is applied in the
plane of the connection and the
bolt group rotates about its
centre of gravity.
A linear variation of loading due
to moment is assumed, with the
bolt furthest from the centre of
gravity of the group carrying the
greatest load. The direct shear is
divided equally between the
bolts and the side plates are
assumed to be rigid.
Lecture 4
1. Bolt group in direct shear and torsion
1
O
Lecture 4
1. Bolt group in direct shear and torsion
F1  F  F  2Fv1FM 1 cos 
2
v1
2
M1
1
M Ed  r1
FM 1 
2
2
 xi   yi
FM1
F1
θ
O
VEd
Fv1 
n
MEd
VEd
Lecture 4
FV1
r1
2. Bolt in direct shear and tension
For tension the resistance is
Where
Lecture 4
2. Bolt in direct shear and tension
For combined shear and tension
the resistance is covered by the
formula
Lecture 4
2. Bolt in direct shear and tension
An approximate method of analysis
that gives conservative results is
described first. A bracket subjected to a
factored load P at an eccentricity e
The centre of rotation is assumed to be
at the bottom bolt in the group. The
loads vary linearly as shown on the
figure, with the maximum load FT in the
top bolt.
The moment of resistance of the bolt
group is:
MR = 2[FT · y1 + FT · y22 / y1 + · · · ]
= 2FT/y1 · [y21 + y22 + …]
= 2FT/y1 .∑ y2
=P.e
The maximum bolt tension is:
FT = P · e · y1/(2 . ∑ y2)
The vertical shear per bolt:
FS = P/No. of bolts
Lecture 4
2. Bolt in direct shear and tension
Lecture 4
‫مالحظة هامة‪:‬‬
‫يمنع الكتابة على الكود منعا ً‬
‫باتا ً وإضافة أي جداول غير‬
‫المصرح بها من قبل أساتذة‬
‫المقرر‪.‬‬
‫‪Lecture 4‬‬
Lecture 4