Finite Element Analysis of Steel and Steel-Concrete Composite Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 542

tensile coupon specimen will be tested in the actual bending condition.
Therefore, only the membrane residual stresses have to be incorporated
in the finite element model. Initial conditions can be specified for particular
nodes or elements, as appropriate. The data can be provided directly in an
external input file or in some cases by a user subroutine or by the results or
output database file from a previous analysis. If initial conditions are not
specified, all initial conditions are considered zero in the model. Various
types of initial conditions can be specified, depending on the analysis to
be performed; however, the type highlighted here is the initial conditions
(stresses). The option can be used to apply stresses in different directions.
When initial stresses are given, the initial stress state may not be an exact
equilibrium state for the finite element model. Therefore, an initial step
should be included to check for equilibrium and iterate, if necessary, to
achieve equilibrium. Further details regarding incorporating initial geomet-
ric imperfections and residual stresses in finite element modeling of steel
structural members are found in [ 5.1 ] .
5.8 MODELING OF SHEAR CONNECTION FOR STEEL-
CONCRETE COMPOSITE BRIDGES
Previous investigations by the author have proposed detailed finite element
models simulating the behavior of shear connections with headed studs in
solid concrete slabs, precast hollow-core concrete slabs, and composite con-
crete slabs with profiled steel sheeting, as reported in [2.68-2.71]. The finite
element models simulated the behavior of headed studs in pushout tests and
resulted in extensive data regarding the shear resistance of the studs, failure
modes, and load-slip characteristic curves of the studs. The finite element
models can be used to represent shear connections in steel-concrete com-
posite bridges. This is attributed to the fact that the finite element models
were used to perform extensive parametric studies. The parametric studies
investigated shear connections having studs with different diameters, which
are used in bridges, as well as investigated shear connections having different
concrete strengths, which are also used in bridges.
As an example, the investigation reported in [2.71] investigated the per-
formance of headed stud shear connectors in composite concrete slabs with
profiled steel sheeting. A nonlinear 3D finite element model was developed
and validated against the pushout tests conducted by Lloyd and Wright [2.57]
and Kim et al. [2.58, 2.59]. The pushout tests carried out by Kim et al.
[2.58, 2.59] provided the shear connection capacity of 13 65 mm headed