domingo, 14 de febrero de 2010

Thesis Proposal


Introduction

State-of-the-art

Non-deterministic methods have been succesfully applied in science since the 50s to tackle uncertanty and to evaluate complexity.
Lately, these very methods, combined with modern calculus tools (Finite Elemet Method, Applied Element Method, Discrete Element Method, ...) are proving very helpful in automotive, aerospatial and naval industries to achieve sofisticated, reliable and precise designs.
On the other hand, new simulation tools have appeared in the last decade that were not possible before the increase in computer power and their clustering and parallelizing capabilities.
Videogame, film and virtual reality industries are using them and simulations flood the media with a quality that often makes it very difficult to separate fiction from truth.
In the building environment, perhaps given some inherent differences in the requirements of the product provided to society, we are still pretty far from those technological advances.
This could be seen as a disadvantegeous position but opens, in fact, a whole world of new opportunities for research.
The thesis proposed here aims to provide a frame where these two not so different disciplines (non-deterministic design methods and computer physics simulation) combine in order to open another path to better design tools.

The determinstic approach to structural design

Modern building design and analysis is almost exclusively based on stiffnes matrix method or, in best cases, on Finite Element software.
These softwares have reached today a considerable level of sophistication and versatility. However, one increasingly important aspect of analysis that these programs are unable to address is that of uncertainty in structural parameters and in loading and boundary conditions.
It is a well known fact that deterministic single- point evaluation of the response may under many circumstances produce an over-designed and excessively conservative system if the presence of parameter scatter is not taken into account.
International building codes, historically, have taken this procedure for granted and nowadays Limit States is the csompulsory method for evaluating any building (Eurocodes, ASCE, ACI,...).
These Limit States are given to the designers on a probability basis but have to be necessarily included into our deterministic analysis in the form of material strenght minoration and force majoration.
An stochastic approach allows us to define the reliability of our design in a different way: by calculating in an straighforward manner the probabilty of failure (or limit state achieving), and then comparing it against the standards.

Ordinary Differential Equations and physics simulation

The second weakness of this deterministic approach to the design of building structures is that tackling non-linearity (buckling of columns, terrain, earthquakes, …) has become an extremely unprecise field, plenty of approximate methods.
Intensive particle-based Lagrangian methods, on the other hand, is a relatively recent field of research (even though it uses classical newtonian physics), where the phenomena stated above simply arises as a consequence of the simultaneous behaviour.

Thesis targets

  • Achieve a computer tool with the following features:
  • Real-time ODE based physics.
  • Behavior-monitored structural elements and parameters.
  • Real-time design visualization and designer interaction.
  • Stochastic methods applied to different structural systems and probability-based evaluation of their reliability.
  • Building forensics of existing or failed buildings
  • Evaluate the adequateness of Lagrangian particle-based methods for engineering purposes.

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