On various instances – most recently in the Paris Agreement of the UNFCCC in 2015 – the global industry recognizes the significance of sustainable development in both its ecological and financial take. In the big picture, the Paris convention aimed to avert the global temperature rise, to control greenhouse gas emissions and to consolidate these efforts in an efficient finance flow.

With concrete being the second most used material in the world (after water), the sustainable business culture in the construction industry is reflected in the life-cycle design for new infrastructure and lifetime extension of existing structures. This is now fostered by impressive progress in the field of design optimization, service life design and global monitoring. Nevertheless, real applications on structures are limited in their number.

The most common practical approach is to analyse existing structures through a life cycle assessment in order to manage the structure’s performance throughout its designated service life. For the life-cycle design of a structure, appropriate specifications and structural detailing (material selection, concrete cover etc.) and adjusted performance/reliability criteria must be fulfilled.

For ageing structures, which actually comprise the vast majority of our existing assets, customised maintenance plans should be devised. The fact that the fatigue and deterioration of a component cannot be precisely estimated in advance is overcome through periodic inspection and monitoring programs. Besides revealing the actual asset’s condition, this approach aims to reliably project the structure’s service life and to help decide if and how an effective life extension of the assets can be accomplished through maintenance measures.

Life cycle concept for existing infrastructure – service life with and without monitoring

Some literature:
Frangopol, Dan M., and Min Liu. “Maintenance and management of civil infrastructure based on condition, safety, optimization, and life-cycle cost∗.”Structure and infrastructure engineering 3.1 (2007): 29-41.

K. Bergmeister. Life-cycle design for the world’s longest tunnel project. In Life-Cycle and Sustainability of Civil Infrastructure Systems: Proceedings of the Third International Symposium on Life-Cycle Civil Engineering, Vienna, Austria, October 3–6, 2012, 51–59, 2012