Tension members - The Behaviour and Design of Steel Structures to EC3 - page 38

(a) (b) (c) (d)

Figure 2.6 Eccentrically and locally connected tension members.

to an angle section through one leg only, to a tee-section through the flange (or
table),ortoachannelsectionthroughtheweb(Figure2.6).Theeffectofeccentric
connections is to induce bending moments in the member, whilst the effect of
connecting to some but not all elements in the cross-section is to cause those
regions most remote from the connection point(s) to carry less load. The latter is
essentially a shear lag effect (see Section 5.4.5). Both of these effects are local
to the connections, decreasing along the member length, and are reduced further
by ductile stress redistribution after the onset of yielding. Members connected by
some but not all of the elements in the cross-section (including those connected
symmetrically as in Figure 2.6d) are also discussed in Section 2.5.
Whiletensionmembersinbendingcanbedesignedrationallybyusingthepro-
cedure described in Section 2.4, simpler methods [1-3] also produce satisfactory
results. In these simpler methods, the effects described above are approximated
by reducing the cross-sectional area of the member (to an effective net area),
and by designing it as if concentrically loaded. For a single angle in tension con-
nected by a single row of bolts in one leg, the effective net section A net , eff to be
used in place of the net area A net in equation 2.4 is defined in EC3-1-8 [4]. It is
dependent on the number of bolts and the pitch p 1 , and for one bolt, is given by

A net , eff = 2.0 ( e 2 − 0.5 d 0 ) t , (2.9)

for two bolts by

A net , eff = β 2 A net , (2.10)

and for three or more bolts by

A net , eff = β 3 A net . (2.11)

The symbols in equations 2.9-2.11 are defined below and in Figure 2.7, and A net
isthenetareaoftheangle.Foranunequalangleconnectedbyitssmallerleg, A net