B Möller and M Liebscher (2005)
Fuzzy multi body systems and fuzzy probabilistic multi body systems and their application for the numerical simulation of controlled demolations od structures
In: Compilation of Abstracts of the, edited by K. J. Bathe. M.I.T., Boston, pages 265.
The controlled demolition of structures at the end of their lifetime is of increasing
importance. The objective of such blasting operations is to shatter
a building in such a way that the remaining debris can be removed
easily. When blasting operations are carried out in urban areas, the
surrounding properties should not be affected by debris or accompanying
ground vibrations.The planning and design of a controlled demolition
depend on a variety of uncertain information. Uncertainty may be of
objective or subjective nature. Objective uncertainty appears in
connection with uncertain observations and measurements, whereas
subjective uncertainty results from information deficits, opinions,
and estimations. A realistic and reliable numerical simulation of
blasting processes requires adequate computational models that are
capable of taking into account data and model uncertainty. A reliable
prediction of the collapse process and its effects with consideration
of uncertainty is the objektive of the current research. In this
presentation a special fuzzy probabilistic multi body system for
the numerical simulation of collapse proccesses is discussed. The
local blasting leads to stiffness reductions and structural member
failure. The statical system is turned into a dynamic one. Several parts
of the structure lose their member bindings partly or completely
during the collapse. Physical effects like collision, friction, and
disconnection of bindings has to take into account by the choosen
numerical model. For the deterministic fundamental solution a partially
flexible multi body system is applied. Flexible bodies represent
potential failure zones undergoing major damages or destructions
during the collapse. This mechanical behavior is modeled by nonlinear
load-displacement-relations that describe crack development, articulation,
and failure. Physical parameters describing a blasting process are
generally not deterministic; they are uncertain. Commonly this applies to
geometric and material parameters. In the stochastic sense each blasting
operation is an individual event that is generally characterized
by limited data and distinctive data uncertainty. The mathematical
description of data uncertainty is realized on the basis of fuzzy
randomness [1]. Fuzzy randomness is a generalized uncertainty model
that includes fuzziness and randomness as special cases. In fuzzy
probabilistic structural analysis [1] the uncertain input parameters
modeled by fuzzy randomness are mapped to fuzzy random results. In
the case of blasting the multi body system algorithm as described
above is applied as mapping model. The fuzzy stochastic analysis of
blasting is demonstrated by way of examples. The authors gratefully
acknowledge the support of the German Research Foundation (DFG).