Steel Designers Manual - TheBestFriend.org

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Steel Designers' Manual - 6th Edition (2003)
682 Bolts
– for the more exact method
where Fs is the applied shear, Ft is the applied tension, Ps is the shear capacity, and
Pt is the tensile capacity. The shear capacity, Ps, may be based on the tension stress
area or on the full shank area as appropriate (see section 23.5.2).
This expression allows that when either the shear or tensile capacity is fully taken
up, the other may be stressed to 40% of its capacity.
Preloaded bolts in friction grip connections that are also subject to externally
applied tension should satisfy:
– for connections designed to be non-slip in service (PsL = 1.1 Ks m P0):
Fs
Ftot
+ £ 1 but Ftot £ Atpt P 11 . P
sL
– for connections designed to be non-slip under factored loads (PsL = 0.9 Ks m P0):
Fs
Ftot
+ £ 1
P 09 . P
sL
where
Fs
Ftot
+ £14 .
P P
s
t
0
0
At is the tensile stress area;
Fs is the applied shear;
Ftot is the total applied tension in the bolt, including the calculated prying force;
P0 is the specified minimum preload, see BS 4604;
Pt is the tension strength of the bolt given in Table 34 of BS 5950-1:2000.
23.5.6 Long joints, large grips and packing
When the joint length in a splice or end connection, Lj, defined as the distance
between the first and last bolt on either side of the joint is greater than 500 mm, the
strength of the joint is reduced by the factor (5500 - Lj)/5000, where Lj is the joint
length as defined in Fig. 23.6. Similarly when the grip length, Tg, the total thickness
of the connected plies, is greater than five times the nominal diameter of the bolts,
the strength of the joint is reduced by the factor 8d/(3d + Tg), where d is the nominal
bolt diameter and Tg is as defined above (see Fig. 23.7).
The total thickness of steel packing, tpa, at a shear plane should not exceed 4d/3,
where d is the nominal bolt diameter. Where tpa exceeds d/3 the shear capacity, Ps,
should be taken as: