Dynamic/earthquake analysis - Computational Analysis and Design of Bridge Structures - page 538

17.4.2 finite element model and analyses
Figure 17.20 depicts the finite element model with their section proper-
ties shown in Table 17.6. The superstructure was modeled with four ele-
ments per span, and the elements axes are located along the centroid of the
superstructure. The total mass of the structure was lumped to the nodes
of the superstructure. The bents were modeled with 3D frame elements
that represent the cap beams and individual columns. Since columns are
pinned to the column bases, two elements were used to model each column
between the top of footing and the soffit of the box girder superstructure;
the upper element represents the plastic hinge, whereas the lower one rep-
resents the rest of column. A rigid link was used to model the connection
in between. The first element from the bottom is a plastic hinge element,
which represents the inelastic behavior of the column. The length of the
plastic hinge was calculated using the following formula in English units
(Priestly et al. 1996):

L Abutment B

L Bent 2

L Bent 1

C L Abutment A

30° skew

30° skew

Rigid link (typical)
Plastic hinge
(typical)

Bent column
(typical)

Support node
at abutment (typical)

Y

X

Z

Global

Figure 17.20 Finite element model of illustration example 1. (Data from Mast et al. 1996.)