Integral bridges - Computational Analysis and Design of Bridge Structures - page 506

10.4 m (34′)
Concrete slab
1.8 m (6′)
Cross bracing
Figure 16.12 Cross section of the illustrated bridge.
the bridge abutment oriented for strong axis bending. Girders, cross brac-
ing, and piles are beams of W30X132, L6X6, and HP10X42, respectively.
The piles are placed such that the bending occurs around their strong
axis. The pile length in this example is 12.5 m (41′), of which 0.3 m (1′) is
within the abutment. The total width of the abutment is equal to the width
of the bridge, 10.4 m (34′) as shown in Figure 16.12.
16.4.1 structure
The model is analyzed using the ANSYS program. The shell element type
that is chosen for the slabs, girders, and piles is SHELL 43, a four-node
plastic shell. The element has plasticity, creep, stress stiffening, large deflec-
tion, and large strain capabilities. The element has six degrees of freedom
at each node: translations in the nodal x -, y -, and z -directions and rota-
tions about the nodal x -, y -, and z -axes. Cross bracings are modeled using
beam elements of type BEAM 4, a 3D elastic beam. BEAM 4 is a uni-
axial element with tension, compression, torsion, and bending capabilities.
The element has six degrees of freedom at each node: translations in the
nodal x -, y -, and z -directions and rotations about the nodal x -, y -, and
z -axes. Abutments are modeled using solid elements of type SOLID 45. The
element has plasticity, creep, swelling, stress stiffening, large deflection,
and large strain capabilities. The element is defined by eight nodes having
three degrees of freedom at each node: translations in the nodal x -, y -, and
z -directions. Multipoint constraint elements, MPC184, with rigid beam
option are used to connect all elements together. MPC184 comprises a gen-
eral class of multipoint constraint elements that implement kinematic con-
straints using Lagrange multipliers. A rigid beam option has six degrees of
freedom at each node: translations and rotations in x -, y -, and z -directions.
As stated, the concrete slab is modeled using shell elements, and a node is
placed at each end of the typical section, along the centerline of each girder,
along each end of the girders' top flange, and at a point halfway between
girders. Beam elements are used to model the cross bracings with the same
nodes at the intersection of webs and flanges. The layout of nodes for the
concrete slab, girders, and cross bracings is shown in Figure 16.13.