Examples of Finite Element Models of Steel Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 563

to transmit the longitudinal load on the deck. A total of six natural
analytic frequencies of the highway bridge were obtained.
Kaliyaperumal et al. [ 6.21 ] presented finite element analyses for dynamic
analysis of steel railway bridges. The analyses of a skew bridge were per-
formed and the results were compared with available field measurements.
Initially, eigenvalue analyses of different models were performed in order
to obtain the fundamental mode shapes and bridge frequencies and to assess
the capability of each model to capture the dynamic behavior of the bridge.
Single-span, three-span, and full bridge models were investigated with dif-
ferent elements such as shell, beam, and combinations of these elements. The
authors found good agreement between the fundamental dynamic proper-
ties of the bridge and empirical results. Following the eigenvalue analyses,
time history dynamic analyses were carried out using the full bridge model.
The analyses were performed for different train speeds. It was shown that
modeling the full bridge using a combination of beam and shell elements
was reasonable and computationally efficient in capturing the dynamic
behavior of a bridge and estimating the mean stress range for fatigue damage
calculations. The finite element models of the bridge were developed using
ABAQUS [1.29]. Models with different degrees of complexity, using shell
and/or beam elements, were developed in order to investigate the effect of
different modeling techniques and computational time on the dynamic
behavior of the bridge. Eight-node reduced integration shell elements
(S8R) and three-node quadratic beam elements (B32) were used in the
FE models. Single-span, three-span, and six-span (full) bridge FE models
were developed and analyzed. Both SS and fixed support conditions were
assumed in the single-span and three-span models at the two ends of the
bridge in order to investigate the effect of boundary conditions. All members
were tied to each other, which is equivalent to assuming rigid connections
between them. The effect of bracings was included via the single-span FE
model by developing a shell model with and a model without bracings.
In all the shell element models, the stiffeners in the main girders were also
modeled. The intermediate supports were modeled as SS. Eigenvalue ana-
lyses were performed for all finite element models of the bridge and the
results, in the form of bridge periods (frequencies). The bridge frequencies
obtained from the finite element analysis were compared with available
empirical formulas suggested by Fryba [ 6.22 ] and the International Union
of Railways [ 6.23 ]. Following the eigenvalue analysis, static and dynamic
finite element analyses were carried out to investigate the overall dynamic
behavior of the bridge. Two different types of dynamic analyses, that is,