Straight and curved steel I-girder bridges - Computational Analysis and Design of Bridge Structures - page 209

Bridge deck
(shell element)
Rigid link
Girder (beam element)
Support (zero-dimensional element)
Figure 7.14 3D brick-beam model.
Chung and Sotelino (2006) used four different techniques to model an
I-girder bridge superstructure. In their approach the bridge deck was mod-
eled using shear flexible shell elements (S8R in the commercial software
ABAQUS, 2007) and the steel girders were modeled by four different models,
named G1, G2, G3, and G4, to assess the suitability of each technique. In the
G1 model, the girder flanges and webs were modeled using shell elements. The
shell elements used to model the flanges were placed at the mid-surface of the
flanges using the offset option in ABAQUS to obtain the correct moment of
inertia of steel girders. The only difference between the G1 and G2 models is
that in the latter the flanges were modeled using beam elements placed at the
location coinciding with the center of the flange. The use of beam elements
reduced the computational cost as compared to G1 model. In the G3 model,
the web was modeled using a beam element and both flanges were modeled
using shell elements. This model was considered further to investigate the
incompatibility that possibly exists between model G1 where the in-plane
rotational DOF of the flange shell and drilling rotational DOF of the web
shell are shared at the flange and web joint. Rigid links were used to connect
the shell and beam elements to ensure full composite action. In the G4 model
either Euler beam elements or shear flexible Timoshenko beam elements were
used to model the steel girder. All four models were evaluated numerically by
looking at the maximum deflection due to concentrated load applied at the
center of a simply supported I-shaped beam (Figure 7.15). It should be noticed
that the analytical solution to this problem is readily available from the theory
of elasticity. G1 and G2 models required significant mesh refinement to con-
verge to the analytical solution as compared to G3 and G4 models.