Form-finding of compressive structures using Prescriptive Dynamic Relaxation

• We present small strain truss and triangular elements for compressive form-finding.
• We modify Dynamic Relaxation form-finding to include element prescription.
• We provide forcing functions to achieve desired segmental geometry.
• A scheme for equilibrium and geometrical convergence is verified.
• Case studies validate the practical application of element geometry prescription.

This paper presents an adaptation of the Dynamic Relaxation method for the form-finding of small-strain compressive structures that can be used to achieve project-specific requirements such as prescribed element lengths. Novel truss and triangle elements are developed to permit large strains in the form-finding model while anticipating the small-strain behavior of the realized structure. Forcing functions are formulated to permit element length prescription using a new iterative technique termed Prescriptive Dynamic Relaxation (PDR). Case studies of a segmental concrete shell and a pedestrian steel bridge illustrate the potential for using PDR to achieve economic and environmentally considerate structural solutions.