Tension members - The Behaviour and Design of Steel Structures to EC3 - page 39

e 1 p 1 p 1

e 2

d 0

Figure 2.7 Definition of symbols for tension connections in single angles.

shouldbetakenasthenetsectionofanequivalentequalangleofleglengthequal
tothesmallerlegoftheunequalangle.Inthecaseofweldedendconnections,for
an equal angle, or an unequal angle connected by its larger leg, the eccentricity
may be neglected, and the effective area A net may be taken as equal to the gross
area A (Clause 4.13(2) of EC3-1-8 [4]).
For a pair of bolts in a single row in an angle leg, β 2 in equation 2.10 is taken
as 0.4 for closely spaced bolts ( p 1 ≤ 2.5 d 0 ) , as 0.7 if they are widely spaced
( p 1 ≥ 5 d 0 ) , or as a linear interpolation for intermediate spacings. For three or
more bolts in a single row in an angle leg, β 3 in equation 2.11 is taken as 0.5 for
closely spaced bolts ( p 1 ≤ 2.5 d 0 ) , as 0.7 if they are widely spaced ( p 1 ≥ 5 d 0 ) ,
or again as a linear interpolation for intermediate spacings.

2.4 Bending of tension members
Tension members often have bending actions caused by eccentric connections,
eccentricloads,ortransverseloads,includingself-weight,asshowninFigure2.8.
These bending actions, which interact with the tensile loads, reduce the ultimate
strengths of tension members, and must therefore be accounted for in design.
The axial tension N and transverse deflections w of a tension member caused
by any bending action induce restoring moments Nw , which oppose the bend-
ing action. It is a common (and conservative) practice to ignore these restoring
momentswhicharesmallwheneitherthebendingdeflections w orthetensileload
N are small. In this case the maximum stress σ max in the member can be safely
approximated by

σ max = σ at + σ bty + σ btz , (2.12)

where σ at = N / A is the average tensile stress and σ bty and σ btz are the maximum
tensile bending stresses caused by the major and minor axis bending actions M y
and M z alone (see Section 5.3). The nominal first yield of the member therefore
occurs when σ max = f y , whence

σ at + σ bty + σ btz = f y . (2.13)

When either the tensile load N or the moments M y and M z are not small, the first
yield prediction of equation 2.13 is inaccurate. A suggested interaction equation