Why did you dedicate your research to the explosion protection effect of plants?
Paul Warnstedt: The idea originally came from Professor Norbert Gebbeken. As a result of the attacks of September 11, 2001, the topic of structural protection also came into focus in Germany. In this context, protective measures against terrorist threats were planned or subsequently implemented for many public buildings.
Now we know that distance offers the most effective protection against explosion hazards. But in addition, all obstacles between the explosion and the structure to be protected influence the explosion loads and can reduce them, if necessary. It is therefore interesting to see whether plants can also make a significant contribution to reducing these stresses. As elements of landscape architecture and the design of urban spaces, they are enormously important and make a valuable contribution to urban ecology. If plants can also be used for explosion protection, we are a big step further on the way to protection systems that meet the demand of a modern society for transparent and open architecture. Combinations with other elements, such as metallic ring meshes, are also conceivable in this context.
Systematic research of the explosion protection properties of plants has only just begun. There are already results from blasting tests, which partly even exceeded the original expectations. For example, the pressure load resulting from an explosion could be reduced by approx. 60% with thujas without causing any significant damage to the plants. However, these results cannot be generalised. Since the corresponding physical test series are extremely complex and cost-intensive, we are developing models for the computer-aided simulation of these processes.
These questions are sometimes completely new territory for a civil engineer. Not only the numerical modelling of such sophisticated structures poses a special challenge. I have already sought the advice of appropriate experts for the preselection of suitable plant species, but the social dimension is also interesting. As engineers, we can answer the question of how protective systems have to be designed in order to be effective. However, we do not know what design requirements these systems should meet in order to give the public a sense of security. As an analogous example, we would like to mention walkable glazing. Even if the load-bearing capacity is undisputed, it costs a great deal of effort to actually put a foot on it. In addition, modern protective systems are themselves threatening, such as military protective structures. I hope that RISK will in future cooperate with colleagues from the humanities, who are better placed to deal with social issues.