Parametric modelling (esa.11)

 

esa.11

The esa.11 module Parametric modelling is employed in the modelling and analysis of structures with flexible input. The use of parametric models (1) eliminates the need to actively adapt the model after changes to the initial design, and (2) enables general optimisation.

Highlights
Almost any property in a model can be defined as a parameter: coordinates, dimensions, material classes, cross-sections, loads, etc.
Formulae are used to express a parameter as a function of other parametrised properties.
A list of defined parameters in tabular form displays upon opening a parametric project. The user then fills in numerical values for the parameters. The structure is generated based on the defined numerical input.
In open projects, SCIA Engineer automatically regenerates the model upon a modification of a parameter. The structure is then ready to be analysed.
Parametrisation is also applicable to user blocks (see esa.00).
Parameters allow for the structure to be optimised so as to obtain the most economical design, minimise a load effect, or maximise/minimise any other property of the 3D model.

Application

Examples of the use of parameters in a model include:

  • Nodes, supports, and loads whose location are defined by parameters;
  • A cross-section of a member that is defined as a parameter;
  • Loads with parametrised magnitude.

A parameter has a type. For example, only parameters of type length can be assigned to distances. Types make it easier to handle units, especially when ranges must be defined for the valid values of a parameter.

The esa.11 module makes it possible to also parametrise libraries. As an example, one parameter type in SCIA Engineer is Cross section -- it allows the user to assign a parametric cross-section to a member. Valid values for this type of parameter are all entries in the Profile Library. To limit the number of cross-sections that are selected, user-defined sets with a limited number of cross-sections can be created in a quick and easy way.

Combined with User Blocks

User Blocks is a standard functionality in SCIA Engineer that allows for common or repeatable structural assemblies to be stored and reused in future models. Continuous beams, trusses, 2D/3D frames, etc. are examples of structures that are stored as User Blocks - these can be assigned cross-sections, supports, loads, connections and saved.

In combination with User Blocks, parametric modelling allows users to prepare parametric structures that can be inserted in any project as a sub-structure taken from the User Block Library. In this way, many types of structures are modelled much faster as one never needs to model from scratch.

Combined with Project Templates

When used in combination with the Project Template functionality of the Productivity Toolbox (module esa.06), the esa.11 module allows users to create parametric projects with predefined geometry, material sets, loads, combinations and calculation report.

The obtained models are effectively simple programs for e.g. the calculation of continuous beams, simple frames, and other standard structures. In this way, design calculations can be performed and documentation be prepared in a matter of minutes in the case of standardised structures.

Boolean operators with parameters

As the final geometry and status of a model is not known in advance for parametric projects, Boolean operators add flexibility to the model definition techniques. For example, loads can be defined to only act in case certain conditions are fulfilled, addition bracing can be added only if the number of spans is high enough to require it, etc.

Parametric User Blocks may contain modular elements, e.g. continuous beams and frames where the number of spans is defined by the end-user.

Summary

When well prepared, parametric modelling may effectively be used for:

  • Analysis of projects where several variants must be prepared and evaluated.
  • Analysis of project where some level of optimisation is necessary.
  • Presentation and teaching purposes when the effect of a change in the input variables should be shown, etc.
  • Parameters enable the fast, easy and simple modification of e.g. structure dimensions, load values, assigned sections, etc.
  • A change in a parameter leads to automatic model regeneration, the newly introduced value is taken into account.

11/02/2014