Civil Engineering Reference
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in steel and steel-concrete composite bridges resulting in additional mem-
brane and bending stresses in cross sections of the bridges as well as longi-
tudinal and lateral thermal expansions. ABAQUS [1.29] provides three
main analyses dealing with temperature effects in different cross sections,
which are uncoupled heat transfer analysis, sequentially coupled thermal-
stress analysis, and fully coupled thermal-stress analysis. Uncoupled heat
transfer analysis deals with heat transfer problems involving conduction,
forced convection, and boundary radiation analyzed in ABAQUS
(Standard). In these analyses, the temperature field is calculated without
the knowledge of the stress/deformation state in the structures being
studied. Pure heat transfer problems can be transient or steady state and linear
or nonlinear. Sequentially coupled thermal-stress analysis can be conducted
in ABAQUS (Standard) if the stress/displacement solution is dependent on a
temperature field, but there is no inverse dependency. Sequentially coupled
thermal-stress analysis is performed by first solving the pure heat transfer
problem and then reading the temperature solution into a stress analysis as
a predefined field. In the stress analysis, the temperature can vary with time
and position but is not changed by the stress analysis solution. ABAQUS
allows for dissimilar meshes between the heat transfer analysis model and
the thermal-stress analysis model. Temperature values will be interpolated
based on element interpolators evaluated at nodes of the thermal-stress
model. Finally, in fully coupled thermal-stress analysis, a coupled
temperature-displacement procedure is used to solve simultaneously for
the stress/displacement and the temperature fields. A coupled analysis is used
when the thermal and mechanical solutions affect each other strongly. Both
ABAQUS (Standard) and ABAQUS (Explicit) provide coupled
temperature-displacement analysis procedures, but the algorithms used by
each program differ considerably. In ABAQUS (Standard), the heat transfer
equations are integrated using a backward-difference scheme, and the
coupled system is solved using Newton's method. These problems can be
transient or steady state and linear or nonlinear. In ABAQUS (Explicit),
the heat transfer equations are integrated using an explicit forward-
difference time integration rule, and the mechanical solution response is
obtained using an explicit central-difference integration rule. Fully coupled
thermal-stress analysis in ABAQUS (Explicit) is always transient.
5.6.2.2 Uncoupled Heat Transfer Analyses
Uncoupled heat transfer analyses are those in which the temperature field is
calculated without consideration of the stress/deformation or the electrical
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