COMPARATIVE STUDIES
Finite element analysis (FEA) is an appropriate tool to
examine the structural response of bolted rail joints to
mechanical loading under varying anomalies and support
conditions. Moreover, the objectives of the modeling effort are:
to identify potential conditions for failure, to interpret the data
collected during field evaluation surveys which are described in
Part I of this two-part series [1], to evaluate “what-if” scenarios,
and to provide guidance for future research.
The commercial code ABAQUS is used to carry out the
present analyses [13]. Joint components (i.e. bars and bolts) are
modeled using three-dimensional solid elements. Rails are also
modeled with 3-D solid elements in the vicinity of the joint and
with beam elements away from the joint. In addition to bolted
rail joints, FEA modeling is carried out for continuous rail.
Calculations based on the classical theory of beams on elastic
foundation [14] are compared to the FEA results for continuous
rail to provide confidence and to verify the modeling approach.
Structural performance of rail joints can be examined through
joint deflections and stresses in the bars. The total stress in
joint bars comprises effects from bending, thermal shrinkage,
and residual stresses. Another contributor is bolt tension.
When joint bars are applied to rail, they are held in place by a
set of nuts and bolts. Torque is applied to each nut to tighten
the hardware and keep it in place. The torque also puts the bolt
shank into tension. The shank tension is reacted by pressures
between the bolt head and the inside face of the nut against the
outside faces of the joint bars. The bolts in the joint assembly
are assigned initial tensioning.