Lateral torsional buckling (LTB) is the important object of research in particular for the steel rolled beams used in building. The models for the LTB verifications of structural safety of these beams are based on many research studies. For the slender girders made up of plates, used in the construction of steel and composite bridges, the same verification models are used, however with a very large conservatism. No intensive theoretical and experimental study exists to validate these models for plate girders used in steel bridges construction.
In the field of the steel bridges, the parameters which play a role in LTB are very numerous and their influence cannot be evaluated with simple investigation methods. Indeed, plate girders of bridges belong to a structure of the space whose behaviour is influenced by their connections with the other elements of the structure and nature of the actions acting on the bridge. In addition plate girders have manufacturing defects, initial deformations and are the seat of residual stresses, completely different from the one of the rolled beams.
The suggested research wants to analyze in an exhaustive and thorough way the resistance to LTB of the plate girders and to propose models to evaluate their resistance to LTB which correspond better to the reality of the behaviour of steel bridges. These models could advantageously be used for better dimensioning steel bridges but also to evaluate in a more realistic way resistance to LTB of existing bridges.
Lateral torsional buckling (LTB) is a complex phenomenon of instability of the beams under bending moments. The current LTB verifications of bridge beams are based on research works relating to only rolled beams used in building for which the characteristics and the behaviour are very different from the plate girders used in bridges.
The objective of this research is to define a method of verification for steel bridge girders, less conservative, by taking into account the specificities of the bridges. Principal works will consiste in numerical simulations by means of calculation models taking into account the particular characteristics of steel and composite bridges girders.
Following steps were made during the project:
- literature search
- 3D numerical simulations
- parametric studies
The main result is a verification method for steel bridge girders via numerical simulations by means of calculation models taking into account the particular characteristics of steel and composite bridges girders.
- Improved knowledge of the dumping of up beams welded bridges.
- Economy in the design of the bridges.
- More realistic assessment of dumping behavior of existing structures.
Modification of standardisation in this area.