Examples of Finite Element Models of Steel-Concrete Composite Bridges - Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges - page 627

both reliable results and less computational time. All the nodes in the middle
symmetry surface were prevented to displace in direction 2-2. The roller
support nodes were prevented to displace in direction 3-3 only. The load
was applied in increments as concentrated static loads at midspan, which
is identical to the experimental investigation [ 7.29 ]. The nonlinear geometry
was included to deal with the large displacement analysis.
The shear forces across the steel plate girder-concrete slab interface of
G2 test [ 7.29 ] are transferred by the mechanical action of headed stud
shear connectors. Similar to G1, in this study, the load-slip characteristic
of the studs used in the test [ 7.29 ] was predicted based on the detailed exper-
imental and numerical investigations [2.68,2.69].
Under uniaxial compression, the response is linear until the value of pro-
portional limit stress is reached which is assumed to equal 0.33 times the
design compressive strength. Under uniaxial tension, the stress-strain
response follows a linear elastic relationship until the value of the failure
stress. The tensile failure stress was assumed to be 0.1 times the compressive
strength of concrete which is assumed to be equal to 0.67 times the measured
concrete cube strength. The concrete cube strength is assumed to be equal to
1.25 the concrete cylinder strength. The softening stress-strain response, past
the maximum tensile stress, was represented by a linear line defined by the
fracture energy and crack band width. The fracture energy G f (energy
required to open a unit area of crack) was taken as 0.12 N/mm as recom-
mended by the CEB [ 7.30 ] and ABAQUS manual [1.29]. The fracture
energy divided by the crack band width was used to define the area under
the softening branch of the tension part of the stress-strain curve. The crack
band width was assumed as the cubic root of the volume between integra-
tion points for a solid element, as recommended by CEB [ 7.30 ] . The rein-
forcement bars used in the concrete slab of the composite plate girder test
[ 7.29 ] were modeled using the (REBAR option) available in the ABAQUS
[1.29] element library. Further details regarding the damaged plasticity
model and the modeling of reinforcement bars can be found in Sections
5.4.3.2 of Chapter 5 in this topic.
The stress-strain curves for the structural steel and reinforcement bars
given in the EC3 [2.11] and EC2 [2.27], respectively, were adopted for
the finite element model of the composite plate girder G1 with measured
values of the yield stress and ultimate stresses reported in Ref. [ 7.29 ] . The
material behavior provided by ABAQUS [1.29] (using the PLASTIC
option) allows a nonlinear stress-strain curve to be used (see Section 5.4.2
of Chapter 5 in this topic). The first part of the nonlinear curve represents