Nonlinear Material Behavior of the Bridge Components - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 89

the direction of the load, its ultimate capacity was reduced. Also, a decrease
in the longitudinal stud spacing resulted in a decrease in ultimate strength. A
further study by Davies [ 2.45 ] showed that when transverse reinforcement is
provided in a solid concrete slab, the cracking resistance of the slab is
improved. The longitudinal cracks only develop when the yield stress of
the reinforcement is reached. Therefore, a certain minimum amount of
transverse reinforcement has to be used, to achieve the maximum load-
carrying capacity of a composite beam. Johnson [ 2.39 ] found that the con-
crete strength influences the mode of failure of shear connection between
steel and concrete, as well as the failure load. Menzies [ 2.46 ] compared
the strengths of shear connectors given in CP 117 part 1 [ 2.34 ] and part 2
[ 2.35 ] with his results of push-off tests. It was found that CP 117 part 1
assumes linear relationships between the static strength of shear connectors
and the concrete strength and CP 117 part 2 assumes that the variation of
fatigue strength of stud connectors with concrete strength was inside limited
range of concrete strengths. Therefore, the author conducted an experimen-
tal investigation comprising 34 push-off specimens to investigate the effect
of concrete strength and density on the static and fatigue strength of connec-
tors. The investigation was carried out over a wide range of concrete
strengths. Different types of connectors, studs, channels, and bars were used,
and the maximum load per connector, the mode of failure, and the slab in
which the failure occurred were given. The maximum static loads per con-
nector were plotted against the compressive strength of both water-stored
and air-stored concrete cubes. The slip in the static tests, that is, the vertical
movement of the slab relative to the steel beam, was plotted for each spec-
imen against the load. The maximum and minimum values of the cyclic load
per connector, the fatigue life, and the mode of failure were given. It was
concluded that a modification of specified strengths of shear connector given
in CP 117 is desirable for a larger range of concrete strengths; a distinction
should be made in design between connectors embedded in normal-density
concrete and lightweight concrete; the static strengths of studs in normal-
density concrete are overestimated in CP 117; when the density of the light-
weight concrete is below 1400 kg/m 3 , there may be difficulty in ensuring
adequate connection strength and an adequate degree of interaction in a
composite beam; and the specification in CP 117 of the fatigue strength
of stud connectors based on percentages of static strength is confirmed when
embedded in normal-density concrete.
Jayas and Hosain [ 2.47 ] conducted tests on 18 full-size push-off speci-
mens and four pull-out specimens. The objective of the project was mainly