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modal dynamic and implicit dynamic, were undertaken to investigate the
suitability of each to capture the dynamic behavior of the bridge. Explicit
dynamic analysis was computationally much more demanding than implicit
analyses, and due to the large nature of the finite element model, this type of
analysis was excluded from this investigation. A range of different train
velocities were employed in the analyses and the results were compared with
the available field measurements. The bridge was loaded with the test loco-
motive and the axle loads of the train (195 kN) were applied directly to the
top flange of the stringers ignoring any load distribution due to the effect of
rails and sleepers.
measurements, evaluation, finite element model simulations, and safety
index calculations on existing steel railway bridges. Dynamic tests were ful-
filled by using a special test train on these bridges to obtain the dynamic
parameters, and these parameters were then used to refine the finite element
models of the bridges. The updated models were used to represent the actual
condition, and safety indexes were calculated for structural components of
the bridges for each loading condition. The safety indexes were used to cal-
culate failure probabilities of structural members. In addition, the authors
performed system reliability of the bridges based on proposed systemmodels
of the bridges. It was shown that the study can provide a reliable background
for proposed heavier axle loads resulting from new freight trains by realizing
the current condition of bridge structures. In employing modal identifica-
tion procedures, the authors identified first vibrational mode. Also, in order
to define modal parameters, after having preprocessed the collected acceler-
ation data using the fast Fourier transform technique, acceleration spectra
were obtained for the bridge. The results of the fast Fourier transform anal-
ysis and modal identification were used to calibrate the computer models of
the bridge. A bridge was modeled with beam elements using the general
tions between members were defined by using rotational spring elements to
simulate the rotational rigidities. Additionally, the supports were modeled
using spring elements and gusset plates were simulated using 1D rigid bar
ering both geometric and material nonlinearities for predicting the ultimate
strength and behavior of multispan suspension bridges. The geometric non-
linearities of the cable members due to sag effects were considered using the
catenary element, while the geometric nonlinearities of the beam-column
members due to second-order effects were considered using the stability
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