Computational form-finding methods for fabric structures

Abstract

Form-finding is a process that determines the surface configuration of a fabric structure under pre-stress. This process can be carried out using a variety of numerical methods, of which the most common are: (i) transient stiffness, (ii) force density, and (iii) dynamic relaxation. This paper describes the three methods, discusses their advantages and limitations, and provides insights into their applicability as numerical tools for the design of fabric structures. Further, it describes various approaches to surface discretisation, and discusses consequences of using 'mesh control' and elastic effects in the design of form-found surfaces. A brief discussion of the general recommendations given in the European Design Guide for tensile surfaces structures concludes the paper. EACM-D-08-00023 W. J. Lewis, Computational form-finding…3

Contemporary free-form pavilions with the Delaunay gridshell patterns

“…Regardless of the chosen technique, achieving the intended goal requires a well-thought-out sequence of actions and the use of the right tools at the right time. Optimal form-finding with the use of parametric tools requires "algorithmic thinking" [7].…”

Determination of prestressing levels for cable trusses as a function of their stability

“…Because of their multiple static indetermination the calculations of such complex structures are highly complex. Two typical approaches are used for determining the stress and deformation: numerical [11][12][13][14][15][16] (Transient Stiffness Method, Force Density Method and Dynamic Relaxation Method) and analytical [1,17,18]. Movements of nodes and forces in bars are obtained, for given geometrical parameters and load values, through calculation of these geometrical nonlinear structures.…”

Efficiency of dynamic relaxation methods in form-finding of tensile membrane structures

“…From the viewpoint of a practicing membrane engineer, Wakefield [7] reviewed the selection and application of appropriate analysis techniques and demonstrated that DRM may be considered as the preferred form-finding method. Lewis [15] discussed the advantages and limitations of three approaches, namely transient stiffness, FD, and DRM. In addition, the study provided insight into their applicability as the numerical tools of design in fabric structures.…”

“…Spherical cap values in the warp and fill directions is assumed equal to 2500 ksi. The form-finding of the structure is investigated subjected to two loading conditions: Case (1) 10 kip forces acting at nodes1,11,12,13,14,15,16, and 17 along the negative Z-direction; and Case (2) 10 kip forces acting at nodes 1 to 17 along the negative Z-direction. The border nodes are fixed.…”