Bridge durability design after EN standards: present and future

Abstract

The paper presents a critical review of the current approach to Bridge Durability Design according to EN Standards, pinpointing several pitfalls. Arguments against the current prescriptive approach are presented, showing its technical and practical shortcomings. The performance approach adopted by Swiss Standards, involving the specification of limiting values of several ‘Durability Performance Indicators’ for different exposure classes, is presented as a successful transit from prescriptive to performance (P2P) specifications. Compliance is checked not only by laboratory testing of cast specimens but also by site measurements. Designing bridges for service lives beyond 50 years imposes the need of predictive models, some of which are also critically discussed. The work of several past and present technical committees dealing with performance specifications and service life modelling should facilitate the P2P process. Areas where the EN Standards need urgent update are highlighted with suggestions on possible paths to be followed.

Keywords:

• Concrete structures
• bridge design
• building codes
• durability
• quality control
• service life
• standardisation

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Corrigendum

Notes

1. The focus is on steel corrosion, although performance tests are also included in SN EN206–1 for frost and sulphate attack.

2. Note that the inclusion of Equation (2(2) $$T_i={\left(\frac{d}{R}\right)}^n$$(2) ) means that second Fick’s Law differential equation is not satisfied by the analytical solution.