Steel Designers Manual - TheBestFriend.org

This material is copyright - all rights reserved. Reproduced under licence from The Steel Construction Institute on 12/2/2007
To buy a hardcopy version of this document call 01344 872775 or go to http://shop.steelbiz.org/
Steel Designers' Manual - 6th Edition (2003)
BS 5400: Part 3 also contains specific rules for the design of:
(1) Batten struts (clause 10.8)
(2) Laced struts (clause 10.9)
(3) Struts connected by perforated cover plates (clause 10.10)
(4) Struts consisting of back-to-back components (clause 10.11).
Economic points 423
These are somewhat more detailed than those of BS 5950: Part 1, particularly in the
matter of determining suitable design forces for the interconnections, i.e. battens,
lacings, etc.
15.8.2 Design of angles, channels and tees
Four specific cases are covered in detail by BS 5950: Part 1:
(1) Single angles in clause 4.7.10.2
(2) Double angles in clause 4.7.10.3
(3) Single channels in clause 4.7.10.4
(4) Single tees in clause 4.7.10.5.
In all cases, guidance is provided on the determination of the slenderness to be used
when obtaining pc for each of the more common forms of fastening arrangement.
In cases where only a single fastener is used at each end the resulting value of pc
should then be reduced to 80% so as to allow for the combined effects of load eccentricity
and lack of rotational end restraint. For ease of use the whole set of
slenderness relationships is grouped together in Table 25.
BS 5400: Part 3 only gives specific consideration to single angles.This distinguishes
between single bolt and ‘other’ forms of end connection. In both cases load eccentricity
may be ignored but for the former only 80% of the calculated resistance may
be used.
15.9 Economic points
Strut design is a relatively straightforward design task involving choice of crosssectional
type, assessment of end restraint and thus effective length, calculation of
slenderness, determination of compressive strength and hence checking that the trial
section can withstand the design load. Certain subsidiary checks may also be
required part way through this process to ensure that the chosen cross section is not
slender (or make suitable allowances if it is) or to guard against local failure in compound
members.Thus only limited opportunities occur for the designer to use judgement
and to make choices on the grounds of economy. Essentially these are