When the Storm Surge Hits the House on the Coast Best Paper Award for Dr.-Ing. Clemens Krautwald from the Leichtweiß-Institute for Hydraulic Engineering and Water Resources

Coastal regions have seen a steady increase in population worldwide over the past decades, as they provide a wealth of important economic and transport services as well as numerous leisure activities. However, these densely populated areas are vulnerable to various natural hazards, such as floods or even tsunamis. Dr.-Ing. Clemens Krautwald from the Leichtweiß-Institute for Hydraulic Engineering and Water Resources (LWI) has investigated which forces act on coastal building houses here during storm surges and how building standards need to be improved. He has now been honoured for his work with the “Coastal Engineering Journal Award of 2022” by the Japan Society of Civil Engineers (JCSE).

After the 2018 earthquake and tsunami in Palu. Photo credit: Clemens Krautwald/TU Braunschweig

How to protect buildings from flooding is one of the questions that people in coastal regions have to deal with more and more often. One strategy: elevate the structures with pile foundations. “Elevated coastal buildings have suffered less damage in recent events because the water has been able to flow underneath the building, reducing the forces on the supporting structures,” explains Dr.-Ing. Clemens Krautwald, research associate in the Department of Hydromechanics, Coastal and Ocean Engineering at LWI. “However, previous research on these forces is limited, especially in the case of extreme events.”

In order to better understand the structural and hydrodynamic processes of the elevated buildings, scientists from the LWI, together with researchers from the Institute of Building Construction and Timber Structures, have carried out and analysed large-scale experimental studies at the Large Wave Flume in Hanover.

Building standards must be improved

Clemens Krautwald is delighted with the Best Paper Award. Photo credit: Clemens Krautwald/TU Braunschweig

Storm surges, tsunamis and dam failures lead to combined loads on buildings. For example, there are lateral hydrostatic pressure forces, which are decisive for vertical building components, such as walls, and buoyancy, which is decisive for horizontal building components (ceilings). Examples of exceptional hydrodynamic loads are also debris impacts, which have recently gained importance in research.

In one of three publications as part of his dissertation thesis, Dr.-Ing. Clemens Krautwald was able to show how great the influence of the height of buildings in relation to the flood depth is for different loads and that building standards need to be improved to take these extreme loads into account in the affected areas. “The choice of elevated building height can reduce horizontal forces, but vertical forces can increase due to flow redirection.” To calculate these forces, the scientists developed a new method that showed good agreement with the measured values. “For the future, improved elevated building forms can be developed for use in endangered areas and the resilience of coastal regions to extreme hydrodynamic events can be improved,” Dr. Clemens Krautwald is certain.