Providing a second service life for bridges
Eugen Brühwiler
Professor, Dr Structural Engineer, Swiss Federal Institute of Technology Lausanne (EPFL) and BridgIng Consultant Lausanne, Switzerland
Current structural engineering often results in invasive interventions on existing bridges including even replacement of bridges. Too many standards and codes, liability issues and a general thinking still driven by new construction largely explain why most structural engineers are over-conservative and lack of motivation and curiosity for innovation and progress in existing structures and life-cycle engineering. Obviously, this situation has to be challenged and changed radically. This change will also rely on scientific research oriented towards effective life-cycle engineering applications.
The basic idea behind our research and application activities is to accurately determine in-situ structural behaviour as well as the targeted use of advanced materials for improvement of structural behaviour of bridges and other structures. The ultimate goal is to limit construction intervention to a strict minimum while providing a second long service life for structures. We call this approach examination engineering (short: Examineering). “Examineering” thus means leaving common “assessment and retrofitting” methods which largely stem from the last Century.
A novel approach is suggested for structural and fatigue safety verification using directly data from in-situ long term structural monitoring to determine updated traffic action effects. In addition, findings from recent research on very-high-cycle-fatigue of reinforced concrete bridge elements allow for more realistic determination of future fatigue life of bridges and of towers of wind turbines.
If interventions are necessary, their objective must be to really improve the structure (not only to repair or retrofit it). A new technology is presented to improve bridges using Ultra-High Performance Fibre Reinforced cement-based Composites (UHPFRC). This novel technology is successfully applied in Switzerland because it is cost-effective while it significantly extends the service life and reduces maintenance of the improved bridges.