Engineering of existing structures

The course principally covers reinforced and prestressed concrete structures.

E. Denarié handles parts on introduction, value of existing structures, deterioration mechanisms, condition evaluation, non-destructive testing, updating of resistances, reinforcement with new concretes, UHPFRC and external prestressing, intervention recommandations, conclusions.

A. Nussbaumer handles parts on updating of action effects, in depth examination: updating by semi-probabilistic analysis, required safety level, condition evaluation and reinforcement by means of glued CFRP lamellas. The course covers the following topics:

- Engineering of existing structures: systematic approach, built estate, range of most frequent issues, socio-economic aspects, material and immaterial value, sustainable development, requirements, terminology.

- Deterioration mechanisms in reinforced concrete: transport phenomena, corrosion due to carbonatation and chlorides,cracking, freeze-thaw, Alkali Aggregate Reaction (AAR), swelling reactions with sulfates, condition evolution and damage, deterioration curves.

- Examination according to SIA 269 Annex A: stepwise approach, updating of resistances (material properties, resistance models) and actions (dead loads, traffic loads, climatic actions), structural analysis models, accidental actions, application of probabilistic methods, required safety level.

- Condition survey and in-depth examination: visual survey, characterization of concrete cover properties (permeability, depth, resistivity), electrochemical potential measurements, impact-echo and GPR, deformation and load measurements in structures.

- Interventions: hybrid concrete members, rehabilitation; strengthening with R-UHPFRC, glued CFRP lamellas, additional prestressing.- Intervention recommendation: monitoring, strengthening, proportionality, cost-benefit ratio.