Examples of Finite Element Models of Steel-Concrete Composite Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 617

linearly with applied load even after certain repeated loading cycles, but the
stiffness reduced gradually with the repeated loading cycles. No serious dam-
age occurred except tiny cracks at the steel-concrete interface caused by slip
after 2 million repeated loading cycles, which meant that all three composite
joints have good fatigue performance. Based on experimental works, 3-D
finite element models of composite joints were developed. The results from
finite element analysis were consistent with those from tests in terms of
strength and stiffness. In addition, the fatigue details involving reinforcing
bars, welding seams, and shear connectors were evaluated according to
related specifications. It was concluded that the presented overall investiga-
tion may provide reference for design and construction of composite joints
in composite truss bridges. The modeling of each composite joint was car-
ried out by using finite element method and software ANSYS [6.10]. The
solid elements (SOLID45) were used to simulate both concrete chord and
steel structures. As for composite action between concrete and steel trusses,
contact elements (TARGE170 and CONTA173) considering the adhesion
effects of steel-concrete interface were employed in numerical models.
When the surfaces are in contact, normal forces develop between two mate-
rials. On the contrary, if the contact element is in tension, the contact sur-
faces separate from each other resulting in no bonding development. In
terms of connectors, three spring elements (COMBIN14) for each stud were
applied to simulate shear and axial forces in three directions; gusset plate with
concrete dowels and perforated plate connectors were modeled by solid ele-
ments (SOLID45) and contact elements, reinforcing bars through the holes,
were not included for the reasons of simplification and safety. The free ends
of truss members were restrained as hinges like the same condition in the
test, and one end of concrete chord was subjected to uniformly distributed
load. Because the structure was almost in elastic state under design load that
was confirmed in static test, linear elastic analysis was used to investigate the
response at different load steps until to design load. More information
regarding recent investigations on steel-concrete composite bridges can
be found in the state-of-the-art review presented by Ranzi et al. [ 7.28 ].
7.3 FINITE ELEMENT MODELING AND RESULTS
OF EXAMPLE 1
The first example presented in this chapter is for a simply supported com-
posite steel plate girder tested by Mans [ 7.29 ], which is denoted in this study
as G1 as shown in Figure 7.1 . The main objective of the test was to