(V) Some Prevention Design Considerations of Fatigue Failures in Suspension Birdges

In Bridge Design the question of the importance of the working loads and the way they are transmitted within the structure is certainly a real issue but it's unfortunately not "statically" the only one !

A second and usually not very well perceived important group of Design Parameters often make the working perimeter being really "time" and "boundary" depending are all the environmental influences over the structure where the evaluation of the risk and the relevance of some of them is really difficult to appreciate due to lack of precedent data. This usually draws up the need of "reliability approaches", Fail Safe Design Procedures, Damage Tolerant Design Consideration, Redundancy and the definition of some adapted maintenance programs over the whole lifetime of the construction.

A big question is to take finely care of some design details that makes the construction as suitable as possible to overtake not only the stresses but also the multiple origin strains (Mechanical deformations, thermal dilatations, Geometric discontinuities, ...) and by this way to also react conveniently to the environment (Working temperatures, chemical influences through the presence of water, condensates, salts, oil, gazoline, ... but too sun & light ray longterm impacts and ageing on/of some specific materials).

This talk will put in evidence the case of a road suspension bridge reviewing some constructives details for longterm operations and helpful "milestones" that give the Engineer some reference point while designing the structure for avoiding mode of longterm potential failure !

It will be shown how it can be really quickly highly complex while dealing with all these multiple time dependant parameters.