Name: KARINA BARTH FERRO
Publication date: 13/10/2025
Examining board:
Name |
Role |
|---|---|
| ADENILCIA FERNANDA GROBERIO CALENZANI | Examinador Interno |
| HERMES CARVALHO | Examinador Interno |
| JOAO VICTOR FRAGOSO DIAS | Presidente |
Summary: In cargo transportation, railways play a complementary role in logistics by enabling the
transport of large volumes with lower energy consumption. To serve this purpose, railway
bridges have been constructed over the years using various materials, among which steel has
gained prominence due to its versatility and the ability to span long distances with lightweight
structures. In these bridges, structural details such as welded connections can feature various
geometric configurations that result in stress concentration points. When combined with
dynamic loading and second-order effects, these stress concentrations make fatigue one of the
primary causes of failure in steel bridges. However, assessments for this type of limit state can
be complex, and more accurate approaches, such as the global-local methodology, can be
employed. Within this context, a fatigue life assessment is conducted on a welded connection
of a railway bridge with a composite steel-concrete structure. The analysis is carried out using
finite element models in the commercial software Ansys Mechanical APDL v. 2020R1,
considering two modeling scales – global and local. Fatigue life is estimated using both the
nominal stress method and the hot-spot stress method. Damage per vehicle passage is computed
based on the stress history, followed by the estimation of the number of load cycles the structure
can withstand, in accordance with the recommendations of the International Institute of
Welding (IIW) and EN 1993-1-9:2005. The results indicate that for the evaluated detail, fatigue
life is not infinite, even when considering the passage of the lightest type of vehicle operating
on the track. Furthermore, it is evident that increases in vehicle weight and traffic speed have a
significant impact on the fatigue life of the detail. Regarding standards and methodologies, the
nominal stress method was found to be non-conservative for fatigue life prediction, whereas
the IIW methodology yielded more conservative results than those provided by EN 1993-1-
9:2005.
Keywords: fatigue; finite element models; railway bridges; hot spot stress; global-local
methodology.
