Thunderstorm analysis offers wind-safer construction
Thunderstorms put lives at risk and cause significant damage to buildings, transport and energy infrastructure, in a very short space of time. There is consensus among scientists that the warming of the Earth’s surface favours convective activity at the base of thunderstorms, which is why their number is increasing. “The short duration and relatively small size of thunderstorms has in the past limited our ability to accurately measure them,” notes THUNDERR project coordinator Maria Pia Repetto from the University of Genoa in Italy. “As a result, and despite the huge amount of research in this field, there is no shared model of thunderstorms, or of their impact on infrastructure.” This represents a serious shortcoming in the field of structural and civil engineering, underscored by the frequent damage caused to small and medium-sized buildings following a thunderstorm. This is in part due to the fact that the maximum power of downbursts is usually developed close to the ground, usually from 50-100 m.
Understanding thunderstorm behaviour
With this in mind, the THUNDERR project, which was funded by the European Research Council, sought to develop more accurate simulations and models of thunderstorm impacts, to facilitate the design of wind-safer structures in a more cost-efficient manner. To begin, an existing wind monitoring network was strengthened with innovative sensors and software, to record data in real time. “This network provided us with a fine description of the local time structure of downbursts,” explains Repetto. “However, this was not enough to derive a detailed model of the spatial structure of thunderstorms.” For this, wind tunnel tests and computational fluid dynamics (CFD) simulations were carried out. In particular, scaled simulations were conducted at the WindEEE Dome, a one-of-a-kind wind tunnel at the University of Western Ontario in Canada. Next, mathematical models to synthesise the data gathered were developed, to capture the main physical features of thunderstorm outflows. “Another key objective was to evaluate thunderstorm actions on structures,” says Repetto. “We know that thunderstorm outflows are transient and short in time, and that structural responses can be evaluated through a spectrum, similar to the impact of earthquakes.” Two structures – 18 m and 50 m high respectively – were fitted with sensory equipment to analyse the behaviour of structures in real conditions. This helped the project team to develop new means of evaluating the resilience of low- and medium-height structures in thunderstorm conditions.
Wind-safer construction
THUNDERR was successful in expanding an existing wind monitoring network, developing new analytical methods for explaining thunderstorm phenomena, and finding new ways of measuring the response of structures to thunderstorms. All results have been collected and made freely available to the scientific community. “The open catalogue provides reliable thunderstorm records to scientists all over the world,” adds Repetto. Improvements in monitoring and modelling will benefit sectors such as ports, where operations are strongly influenced by weather conditions. Other infrastructures exposed to wind hazards also stand to benefit from improved monitoring. New models of thunderstorm loading will benefit the construction sector, which can apply these in order to build wind-safer and more cost-efficient structures. Repetto also hopes that the project will leave behind a lasting legacy in education, by bringing together wind science and engineering courses in a truly multidisciplinary manner. Next steps include analysing the impact of thunderstorms within the context of climate change, applying artificial intelligence and big data analysis, and focusing on the impact of thunderstorms on transport systems.
Keywords
THUNDERR, thunderstorm, engineering, downbursts, wind, weather, transport, energy, infrastructure
