Parametric Propagation of Form
by Peter Szalapaj
The ĢI30 million International Terminal at Waterloo Station, London, by the architecture firm Nicholas Grimshaw & Partners, is a railway station on a complex site. It handles up to 15 million passengers a year and was completed within budget and on time in May 1993. The most impressive feature of the scheme from a CAD perspective is the massive curved train shed which gradually expands towards the station end.
The complexity and variation in the size and shape of the structural elements involved in the train shed were possible because of the application of structural analysis CAD techniques, the essential feature of which was the ability to represent parametric relationships.
A parameter is a variable to which other variables are related, and these other variables can be obtained by means of parametric equations. The main parametric relationships involved in this project were concerned with the description of the structural form, in which the span and curvatures of individual arches were related. These relationships in turn determined the detail of the trusses.
Expressing the Structure Parametrically
The asymmetry of the trusses derives from the position of a single track tight onto the western edge of the site and the resulting need for the structure to rise more steeply at this point to clear the trains.
This article is excerpted from CAD Principles for Architectural Design by Peter Szalapaj, with permission of the publisher, Architectural Press.