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Investigation of controlled building collapse – analysis and validation
Gunther Blankenhorn, Steffen Mattern, Karl Schweizerhof
Institute for mechanics, University Karlsruhe (TH), Englerstr. 2, D-76131 Karlsruhe,
Germany, Gunther.Blankenhorn@ifm.uni-karlsruhe.de
Controlled destruction of buildings at the end of their life cycle has become more and more
important. These buildings are either no longer attractive in an architectural sense or did not
reach suffice standards. Especially industrial buildings which are no longer used because of
technological or business reasons are often demolished by controlled explosives. To avoid
damage of neighboring buildings or traffic facilities an accurate prediction of the effects of the
building collapse and the building debris is needed. Otherwise uncontrolled collapse may
cause a great physical and major collateral damage.
After several accidental events caused by apparently controlled demolition with explosives,
the research unit FOR 500 [1] funded by the German research Foundation (DFG – Deutsche
Forschungsgemeinschaft) has been formed. A main goal is the efficient and reliable
prediction of controlled collapse of reinforced concrete buildings. Investigations are done in
the fields of numerical methods, dealing with uncertainty data in numerical analysis, different
modeling approaches and optimization of blasting strategies for buildings. Four civil
engineering departments in Germany are included in this research unit.
The subproject in the focus of this contribution performed at Karlsruhe University has the
goal to investigate the collapse sequence of the building by the Finite Element Method. The
goal is to allow a detailed look at the phenomena which drive the problem and to validate
also more simple and efficient alternative analysis.
On this behalf the idealization of some structural parts as rigid is done, which speeds up the
calculation time, but has to be based on correct behavioral observations. Otherwise such
simple models may lead to wrong predictions mostly due to ignoring contacts and dynamic
effects.
As an example the blast demolition of an industrial building is investigated. The commercial
code LS-DYNA [2] is used for these investigations. Modeling and discretization aspects
concerning simplifications are discussed. Several studies with flexible and partially rigid parts
were performed. As no measurement data were available a validation is performed by a
video sequence, overlaying visualized numerical results and pictures from a video tape of the
real collapse. With reasonable assumptions fairly good predictions of collapse can be
achieved, which can then serve as a basis for simplified analyse e.g. with rigid body
programs [3].
[1] DFG Forschergruppe 500, http://www.sprengen.net, 2006.
[2] J.O. Hallquist, LS-DYNA, vs 971, Livermore Software Technology Cooperation, 2006.
[3] Research unit FOR500, Subproject 5: Object-oriented software system for multi-level
simulation and optimisation of explosive demolition processes of the global structures,
Institute for Computational Engineering, Ruhr-University Bochum, Germany,
http://www.sprengen.net, 2007
