Nonlinear Material Behavior of the Bridge Components - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 101

elements of zero length, which can bear only shear force and obey the load-
deformation law of the shear connectors, were used to connect steel and
concrete. The authors have concluded that consideration of the actual
load-deformation diagram of studs in the design of composite girders is
needed and increases the safety of the beam at the serviceability limit state.
Studies carried out by Oehlers et al. [ 2.76 ] and by Oven et al. [ 2.77 ]
investigated numerically the behavior of composite steel-solid slab beams.
Oehlers et al. [ 2.76 ] found that in the maximum flexural capacity of com-
posite beams, where the axial strength of the concrete section is usually
much larger than that of the steel section, partial interaction has virtually
no effect on the strength. Conversely, partial interaction can reduce the
strength of composite beams with very strong steel sections, where the axial
strength of the steel section is much greater than that of the concrete section.
Also, it has been found that the greatest effect of partial interaction is to
reduce the strain in the steel element and hence limit the beneficial effects
of strain hardening. The work of the authors was part of an ongoing study,
and a computer model has been developed to carry out the parametric study,
while Oven et al. [ 2.77 ] developed a 2D nonlinear inelastic finite element
model for the structural analysis of steel-solid slab composite beams with
flexible shear connection. The effects of slip between the steel beam and
the concrete slab and the nonlinear nature of force-slip characteristics of
the shear connectors were included. The model was based on a 2D nonlinear
FE analysis program INSTAF, developed originally for steel frames by
El-Zanaty [ 2.78 ] . The program used a line element with 4 degrees of free-
dom at each node to represent the steel I-section and the concrete slab. The
material nonlinearities of the composite girder components have been
incorporated. The author concluded that the model can be used to predict
the load-deflection behavior and the slip distribution along the length of the
beam and the model has been validated by comparing the results with pub-
lished test data. Cai et al. [ 2.79 ] investigated the behavior of cable-stayed
composite bridges. The author developed a finite element model to repre-
sent the shear connection between a steel beam and a concrete slab. A 2D
finite element was used in their analysis to model the steel beam and the con-
crete slab. The two elements are then connected via rigid links to model the
shear connectors, and hence, they eliminated slip at the steel-concrete inter-
face. The composite connection between steel beam and solid concrete slab
was modeled by Youn and Chang [ 2.80 ] using 3D finite elements. The
model consisted of two layers of solid elements and 3D beam elements.
Rigid links were used between the concrete slab and the girders.