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Steel Designers' Manual - 6th Edition (2003)
614 Composite beams
load per
shear—
connector
0.6 u
5 mm slip
Fig. 21.9 Load–slip relationship for ductile welded shear-connector
Higher tensile strengths (495 N/mm 2 ) are required in bridge design. 5 Nevertheless,
the ‘push-out’ strength of the shear-connectors is relatively insensitive to the
strength of the steel because failure is usually one of the concrete crushing for concrete
grades less than 40. Also the weld collar around the base of the shearconnector
contributes to increased shear resistance.
The modern method of attaching studs in composite buildings is by through-deck
welding. An example of this is shown in Fig. 21.10. The common in situ method of
checking the adequacy of the weld is the bend-test, a reasonably easy method of
quality control which should be carried out on a proportion of studs (say 1 in 50)
and the first 2 to 3 after start up.
Other forms of shear-connector such as the shot-fired connector have been developed
(Fig. 21.11). The strength of these types is controlled by the size of the pins
used. Typical strengths are 30%–40% of the strengths of welded shear-connectors,
but they demonstrate greater ductility.
The static resistances of stud shear-connectors are given in Table 21.4, taken from
BS 5400: Part 5 and also incorporated in BS 5950: Part 3. As-welded heights are
some 5 mm less than the nominal heights for through-deck welding; for studs welded
directly to beams the length after welding (LAW) is taken as the nominal height.
The strengths of shear-connectors in structural lightweight concrete (density
>1750 kg/m 2 ) are taken as 90% of these values.
In Eurocode 4, 8 the approach is slightly different. Empirical formulae are given