Nonlinear Material Behavior of the Bridge Components - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 96

approximately with those evaluated from the tensile strength of the stud
shear connectors. Also, an empirical equation for the initial shear stiffness
of a shear connection was proposed.
Nip and Lam [ 2.63 ] investigated the effect of end conditions of hollow
core slabs on longitudinal shear capacity of composite beams. The published
work was an extension for Lam et al. [ 2.61 ] and mainly concerned about
push-off tests with precast hollow core concrete slab of square ends (see
Figures 2.16 and 2.17 ). Eighteen push-off tests (12 push-off tests with precast
hollow core slab of square ends, 2 push-off tests with precast hollow core slab
of tapered ends, and 4 push-off tests with solid slab) were carried out by the
authors. The same horizontal push-off testing approach used by Lam et al.
[ 2.61 ] was used. The headed studs used had 19 mm diameter and
100 mm height. The precast floor specimens consisted of four 600 mmwide
hollow core units connected to a 254 254 73 UC. Each beam had six
prewelded studs at 150 mm centers. The effects of transverse reinforcement
size, gap width, and in situ concrete strength were discussed by the authors.
The authors concluded that 100 mm high headed studs with square-end
hollow core slabs performed as well as the 125 mm high headed studs with
tapered-end hollow core slabs. It is also concluded that the optimum in situ
gap width that should be used for square-end hollow core slab is 80 mm and
16 mm diameter high-tensile bars are recommended to be used as transverse
reinforcement to ensure a slip ductility of 6 mm at the maximum load.
2.6.7 Main Investigations on Numerical Modeling of Shear
Connection
Finite element modeling could provide a good insight into the behavior of
shear connection and compensate the lack in the experimental data. Nether-
cot [ 2.64 ] highlighted the importance of combining experimental and
numerical study in advancing structural engineering understanding. The
author mentioned that there is a lack in the detailed numerical studies deal-
ing with the behavior of the individual connector. It is also mentioned that
the absence of experimental/numerical approach means that real under-
standing is lacking and design expressions are very limited. Limited numer-
ical models have been found in the literature for push-off tests with different
slabs. Initially, Johnson and Oehlers [ 2.65 ] used a simplified purpose-written
program, developed originally by Oehlers [ 2.66 ], in their parametric study
to predict the shank failure loads of headed stud in steel-solid slab push-off
test and the influence of weld collar on forces acting on the stud. The pro-
gram performed a step-by-step plane stress elastic analysis using triangular