Applied Loads and Stability of Steel and Steel-Concrete Composite Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 184

3.8.6.4 Shear Connection
As mentioned previously, Section 2.6 of Chapter 2 , the behavior of shear
connection is of great importance in the design of steel-concrete composite
bridges. The design rules governing shear connection is also covered by EC4
[ 3.6 ] . The code recommends that shear connection and transverse reinforce-
ment shall be provided in composite beams to transmit the longitudinal shear
force between the concrete and the structural steel element, ignoring the
effect of natural bond between the two. Shear connectors shall have suffi-
cient deformation capacity to justify any inelastic redistribution of shear
assumed in design. Ductile connectors are those with sufficient deformation
capacity to justify the assumption of ideal plastic behavior of the shear con-
nection in the structure considered. A connector may be taken as ductile if
the characteristic slip capacity d uk is at least 6 mm, with the evaluation of d uk
given in Annex B of EC4 [2.37]. Where two or more different types of shear
connection are used within the same span of a beam, account shall be taken
of any significant difference in their load-slip properties. Shear connectors
shall be capable of preventing separation of the concrete element from
the steel element, except where separation is prevented by other means.
To prevent separation of the slab, shear connectors should be designed to
resist a nominal ultimate tensile force, perpendicular to the plane of the steel
flange, of at least 0.1 times the design ultimate shear resistance of the con-
nectors. If necessary, they should be supplemented by anchoring devices.
Headed stud shear connectors may be assumed to provide sufficient resis-
tance to uplift, unless the shear connection is subjected to direct tension.
Longitudinal shear failure and splitting of the concrete slab due to concen-
trated forces applied by the connectors shall be prevented.
According to EC4 [ 3.6 ] , for verifications for ultimate limit states, the size
and spacing of shear connectors may be kept constant over any length where
the design longitudinal shear per unit length does not exceed the longitudi-
nal design shear resistance by more than 10%. Over every such length, the
total design longitudinal shear force should not exceed the total design shear
resistance. EC4 [ 3.6 ] specifies that for any load combination and arrange-
ment of design actions, the longitudinal shear per unit length at the interface
between steel and concrete in a composite member, v L,Ed , should be deter-
mined from the rate of change of the longitudinal force in either the steel or
the concrete element of the composite section. Where elastic theory is used
for calculating resistances of sections, the envelope of transverse shear force
in the relevant direction may be used. In general, the elastic properties of the
uncracked section should be used for the determination of the longitudinal