Parametric modelling

- A form finding issue

  • Perspective view of a shell showing the influence of changing boundary condition on the funicular shape using the genetic algorithm approach. Illustration: NTNU/Marcin Luczkowski.

     

     

  • Front view of a shell showing the influence of changing boundary condition on the funicular shape using the genetic algorithm approach. Illustration: NTNU/Marcin Luczkowski.

     

     

In the last two decades, design of free-form structures with complex shape and irregular geometry has become one of the most popular architectural designing approaches, mostly due to the development of parametric CAD software. Without the use of parametric modelling, the design phase of structures with sophisticated, sculptural forms may be cumbersome due to lack of specific information concerning load, boundary conditions, and most importantly, topology. To make the designing process more efficient, a parametric designing toolkit including form finding is preferable.

Force and form diagram for a shell example. Illustration: NTNU/Marcin Luczkowski.

Form finding methods are considered an essential part of the parametric designing toolkit, and since the 1960s, theoretical foundations have been developed, resulting in several methods with different purposes. Some of these methods are dedicated to, for instance, cable net structures, structures exposed solely to compression and gridshells. Kinematic gridshells and thin concrete shells especially have benefitted greatly in their design due to the use of form finding. These structures require that the engineer not only take part in the structural engineering part of the design, but also the conceptual phase.

The main goal of this on-going research topic is to study well-known form finding methods such as the force density method, dynamic relaxation, thrust network analysis and genetic algorithm, and evaluate how they can be applied in a parametric framework.  Although the two first-mentioned methods are widely recognized as the most promising ones, it is considered as equally important to focus on the universality of the method itself as well as the simplicity for implementation in a parametric modelling environment.  

State of equilibrium in a single point in a bar. Illustration: NTNU/Marcin Luczkowski.

Projects:

There are currently two PhD candidates working with parametric modelling: 

References:

Luczkowski M., Mork J.H., Rønnquist A., Manum B. (2016) A form finding issue in parametric modeling, accepted, IABSE Conference, Stockholm, 2016.

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