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finite elements. Initially, one stud and one slab of a push-off test specimen
were modeled. The stud shank and the weld collar were assumed to be of
square cross section. The program took into account two types of local fail-
ure, cracking due to tensile stress and cracking due to tensile strain caused by
normal compressive stress. The program was used in two modes: linear elas-
tic analyses of isotropic materials with and without the provision for con-
crete to fail in tension. In both modes, the shear connection was assumed
to have reached its maximum strength when the maximum stress in the
shank of the stud reached the measured ultimate tensile strength of the
shank. The failure of concrete in compression was not modeled in this study.
The authors found that a weld collar less than 5 mm high attracts 70% of the
total shear and reduces the bending moment at the base of the stud to one-
third of the value found for a stud without a collar.
The inelastic behavior of shear connections was investigated by Kalfas
behavior of shear connectors in a steel-solid slab push-off test. The results
were compared with a series of push-off tests performed in the steel-
structures laboratory of Democritus University of Thrace. The model sim-
ulated the linear and nonlinear behavior of the materials (bilinear stress-strain
curves were used for concrete and headed stud shear connector). The three
components of a push-off test were simulated with different types of standard
finite elements. The concrete slab was modeled by nonlinear volume ele-
ments, the steel beam by a rigid bar element, and the shear connectors by
nonlinear beam elements as shown in
Figure 2.24
. The finite element pack-
age COSMOS was used in the analysis. The load-slip curve obtained from
the finite element solution was compared with experimental results, and the
maximum deviation between the results was about 14%. Although the con-
crete slab was modeled with 1920 elements, the results obtained were inac-
curate and this may be attributed to the incompatibility of the FE elements
used. The predicted shear stud capacity is considerably higher than that tab-
ulated in BS 5950 and Eurocode 4, and the mode of failure was not inves-
tigated. The authors suggested to improve the material models by including
the strain hardening of steel, contribution of concrete rebars, and small ten-
sile branch of the stress-strain diagram of concrete to reduce the deviation
between experimental and FE solution. The behavior of headed shear stud
connector in a steel-full-depth precast slab push-off test was modeled
push-off test specimen shown in
Figure 2.23
, previously discussed, was con-
structed using the finite element method. The purpose of the model was to
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