Tension members - The Behaviour and Design of Steel Structures to EC3 - page 37

A

B

p

N N

C

p

D

E

s s

Figure 2.5 Possible failure path with staggered holes.

totheload.Theminimumamountofstagger s m forwhichaholenolongerreduces
theareaofthememberdependsonthediameter d 0 oftheholeandtheinclination
p / s of the failure path, where p is the gauge distance between the rows of holes.
An approximate expression for this minimum stagger is

s m ≈ ( 4 pd 0 ) 1 / 2 . (2.6)

When the actual stagger s is less than s m , some reduced part of the hole area
A h must be deducted from the gross area A , and this can be approximated by
A h = d 0 t ( 1 − s 2 / s m ) , whence

A h = d 0 t ( 1 − s 2 / 4 pd 0 ) ,

(2.7)

s 2 t / 4 p ,

A net = A − d 0 t + (2.8)

where the summations are made for all the holes on the zig-zag path considered,
and for all the staggers in the path. The use of equation 2.8 is allowed for in
Clause 6.2.2.2 of EC3, and is illustrated in Section 2.7.1.
Holesintensionmembersalsocauselocalstressincreasesattheholeboundaries,
as well as the increased average stresses N / A net discussed above. These local
stress concentrations and their influence on member strength are discussed later
in Section 2.5.

2.3 Eccentrically and locally connected
tension members
In many cases the fabrication of tension members is simplified by making their
end connections eccentric (i.e. the centroid of the connection does not coincide
with the centroidal axis of the member) and by connecting to some but not all of
theelementsinthecross-section.Itiscommon,forexample,tomakeconnections