In order to meet the European strategic energy and climate targets for smart, sustainable and inclusive growth by 2020 and ensure the transition to a low-carbon economy by 2050, Europe needs to invest in research to modernise energy and transport infrastructure in the coming years. Without the adequate infrastructure, the costs of this transition will increase. Some infrastructure has experienced a fast rate of deterioration as a result of poor design/construction or more demanding loads than anticipated, and many building, transport and energy infrastructures are getting close to the ends of their design lives.
The cost of repairing faults in a large structure once the fault starts to approach criticality, is enormous, as illustrated by the figure, however, there is no easy way to measure how infrastructure deteriorates over time. Transport and energy networks need to be sustainable, and infrastructure need to be ‘smarter’, i.e., to incorporate more sensors and algorithms that will make greater use of remote sensing and monitoring allowing for an assessment in real time and a prioritization of the measures necessary to ensure their structural integrity and safety. The knowledge gathered from monitoring loads and structural response can also be exploited to provide more efficient structural designs in the future. For example, smart and integrated measures in transport infrastructure design, maintenance and operations are estimated to contribute to a 25% reduction in fuel and energy consumption for today’s vehicles. However, the recent example of the failure of a key bridge for the London Olympics illustrates the consequences of the legacy of European aged infrastructure.
Continued economic growth in Europe requires a functioning infrastructure. In addition to providing better infrastructure planning, TRUSS will make infrastructure last longer and be safer. TRUSS has a great potential for intersectoral application of results with research on steel, concrete and composite structures extending over a wide range of infrastructure types:
Application of new technologies to structural safety
Because many engineering materials exhibit time and stress-path dependent properties and loads tend to be highly variable (e.g., traffic, wind, environmental), the calculations need to be performed within a probabilistic framework. In the design phase, loading conditions are overestimated and structural strength underestimated to cater for the inherent uncertainties associated with in-service conditions. While the cost of providing this enhanced level of safety may be marginal at the design stage, the same cannot be said for assessment, where over conservatism can lead to considerable unnecessary replacement or strengthening of existing structures and a misallocation of the limited available resources.
Indeed the greatest benefit may result from assessing an existing structure as much of the uncertainty contained in the mathematical models used during design can be removed using measurements. For this reason, emphasis is placed upon the rapid evolution of Structural Health Monitoring (SHM) technology and the urgent need for the next generation of experts, trained in these new techniques to assess structural safety accurately.
For example, when the bridge that collapsed in Minneapolis in 2007 was replaced by a new bridge, an early-warning system made up of 323 networked sensors was embedded in the structure (wire and fiber optic strain and displacement gauges, accelerometers, potentiometers, and corrosion sensors). These sensors monitor structural weakness such as corroded concrete or overly strained joints. The cost for all the electronics and technology was about $1 million, a small fraction of the bridge’s $234 million cost. This approach constitutes a model for the future direction of structures – they will incorporate more sensors and algorithms which will improve safety and prolong their lives, reducing demand for non-renewable resources. TRUSS is timely because it has the potential to make significant use of the newly available sensors for tuning advanced load, structural and material models that will facilitate a more accurate assessment of the safety associated to an existing structure or to a new design.