Probabilistic assessment of cable residual strength

The large number of broken wires found in the suspension cables of some bridges in France and overseas has largely highlighted the absence of methods for assessing safety levels provided by old suspensions. This paper tempts to solve this problem through the introduction of a probabilistic model. A suspension cable can be compared to a system made up of parallel strands. A strand itself consists of a set of twisted wires. The cable behaviour can be consequently studied as a multi-scale analysis distinguishing the wire scale, the strand scale and the cable scale. For the wire scale, it is necessary to distinguish the wire itself and the wire layer whereas on the strand scale, it will be the strand segment characterized by the recovery length and the strand itself. Monte-Carlo simulations are used to determine the behaviour of strand segments. These simulations are then used to build a general constitutive law for strands used in the next stages of the multi-scale analysis. Corrosion effects are included at various stages and help to assess the time-evolution of the cable strength. The approach is illustrated on a real case.

• Introduction

• Wire Modelling

• Corrosion Process

• Strand Modelling

• Cable Modelling

• Conclusions

• References