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Steel Designers' Manual - 6th Edition (2003)
384 Tension members
(e) ropes and cables. Further discussion on these types of tension members is
included in section 14.7 and Chapter 5, section 5.3.
The main types of tension members are shown in Fig. 14.1.
Typical uses of tension members are:
(a) tension chords and internal ties in trusses and lattice girders in buildings and
bridges.
(b) bracing members in buildings.
(c) main cables and deck suspension cables in cable-stayed and suspension bridges.
(d) hangers in suspended structures.
Typical uses of tension members in buildings and bridges are shown in Fig. 14.2.
14.3 Design for axial tension
Rolled sections behave similarly to tensile test specimens under direct tension
(Fig. 14.1).
For a straight member subject to direct tension, F:
F
tensile stress, ft
=
A
FL
elongation, d L = ( in the linear elastic range)
AE
load at yield, Py = PyA = load at failure (neglecting strain hardening)
For typical stress–strain curves for structural steel and wire rope see Fig. 14.3.
14.3.1 BS 5950: Part 1
The design of axially loaded tension members is given in Clause 4.6.1. The tension
capacity is
Pt = pyAe
where Ae is the sum of the net effective areas (defined in Clause 3.4.3). Here a steel
grade dependent factor Ke is used to determine the effective net area from the actual
net area of a member with holes, i.e. the gross area less deductions for fastener holes.
Reference should be made to clause 3.4.4.3 for members with staggered holes.
The values for coefficient Ke, given below for steels complying with BS5950-2,
come from results which show that the presence of holes does not reduce the effective
capacity of a member in tension provided that the ratio of the net area to the