Keywords: controlled collapse, fuzzy analysis, uncertainty, multibody dynamics, finite element method.

The controlled demolition of dilapidated buildings, leading to structural collapse is a complex process which requires a detailed planning, supported by sophisticated simulation concepts. Within the research on structural collapse, many numerical approaches were investigated in order to obtain simulations close to reality. The application of the discrete element method, the extended distinct element method or the applied element method [1] was considered.

In this contribution a new concept for the controlled collapse simulation considering uncertainty is presented. The model uncertainty connected with the choice of computational model for the same collapse issue and additionally the uncertainty within each of the models was considered. For those investigations the fuzzy structural analysis with two computational models for the deterministic fundamental solutions was applied [2]. The first computational model considered here is based on special multibody systems, while the second one is based on finite element method [3].

An extensive comparison of those two numerical approaches is presented. In the deterministic formulation the simulations on the basis of both methods show a relative good agreement. Small differences in results are caused inter alia by the fact, that model parameters, set as crisp values can not be defined with the necessary accuracy. This concerns primarily model parameters responsible for the formulation of contact. Therefore, in further investigations those parameters were modelled as fuzzy variables and the uncertainty obtained in the results was analysed. Time dependent results (fuzzy processes) as well as time-independent results (fuzzy variables) were compared.

The analysis of fuzzy variables shows a large spread in the results of the finite element simulation, which leads to the conclusion that the choice of model parameter configuration affects the simulation output significantly. The results from the multibody simulation do not spread as much as the results from the finite element simulation. The comparison of fuzzy processes was done in order to follow the progression of uncertainty in time. Generally, a very good agreement between the processes obtained from both methods can be stated. Though, in the result of finite element simulation the uncertainty becomes significant in the later collapse stages and increases radically, while in the results of multibody approach the uncertainty is present much earlier but does not increase significantly during the simulation.

1

H. Tagel-Din, K. Meguro, "Applied element method used for large displacement structural analysis", Journal of Natural Disaster Science, 24, 1, 25-34, 2002.

2

B. Möller, M. Beer, "Fuzzy randomness - Uncertainty in Civil Engineering and Computational Mechanics", Springer, Berlin, 2004.

3

D. Hartmann, M. Breidt, V. Nguyen, F. Stangenberg, S. Höhler, K. Schweizerhof, S. Mattern, G. Blankenhorn, B. Möller, M. Liebscher, "Structural collapse simulation under consideration of uncertainty - Fundamental concepts and results", Computers & Structures, 86, 2064-2078, 2008. doi:10.1016/j.compstruc.2008.03.004

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