Examples of Finite Element Models of Steel-Concrete Composite Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 602

Barth and Wu [ 7.2 ] performed 3-D nonlinear finite element analyses to
predict ultimate load behavior of slab on steel stringer bridge superstructures.
The study was accomplished using the general-purpose finite element soft-
ware ABAQUS [1.29]. Two composite steel girders fabricated from high-
performance steel and one four-span continuous composite steel bridge
tested to failure have been used to validate the proposed finite element
models. In the study, four-node general-purpose shell element with reduced
integration (S4R) was used for the steel girders, concrete slab, and stiffeners.
The steel reinforcement in the concrete was provided by means of rebar ele-
ments. A 3-D two-node beam element (B31) was used to represent cross
frames. Full composite action between the RC deck and the steel girder
is developed using a beam-type multipoint constraint (MPC beam) between
the girder top flange and the deck, which assures nodal compatibility at these
locations. The authors mentioned that, to obtain accurate results from the
nonlinear finite element analysis, consideration must be given to the element
size and mesh density selection. Selection of relatively small elements will
eliminate unrealistically low predicted strengths due to the effects of stress
concentrations, while incorporating relatively large elements will reduce
the need to modify the constitutive model to prevent an overestimation
of the energy dissipation capacity [ 7.3 ] . The analyses incorporated nonlinear
material behavior including a trilinear stress-strain response for structural
steel and a complete nonlinear stress-strain curve for steel reinforcement.
Concrete was modeled using two concrete models: the smeared crack con-
crete and concrete damaged plasticity models. The modified Riks method
was used in the finite element analyses.
Chung and Sotelino [ 7.4 ] investigated finite element modeling of com-
posite steel girder bridges, with the overall flexural behavior of the bridges
being the main concern. Four 3-D finite element bridge models were inves-
tigated. The finite element models were validated against the results of full-
scale tests and a field test conducted by other researchers. In addition, the
finite element results were compared with the results of a detailed finite ele-
ment model that uses solid elements. The numerical simulations were per-
formed using the general-purpose finite element software ABAQUS [1.29].
The authors mentioned that the bridge deck can be modeled either by solid
or shell elements. Several shell elements were tested to evaluate their appli-
cability for bridge deck modeling. It was found that a quadrilateral nine-
node or eight-node shell element with reduced integration (S9R5/S8R5)
and a quadrilateral eight-node thick shell element with reduced integration
(S8R) predicted the same response. It was also recommended that the