This paper describes a method for the form finding of shell structures composed of both compression and tension members which may lie in one layer or two layers. The length of some of the members can be constrained to a fixed length yielding some control of the resulting form found shape. The form finding is accomplished by adjusting the nodal positions until an equilibrium state is reached using dynamic relaxation. If part of a structure is unstable due to compression forces, then a negative mass must be used in the dynamic relaxation. The length constraint is met by adjusting the force density during form finding, again using dynamic relaxation. Finally, case studies are presented where the applied load and the pretestress is used to govern the form found shape.
Keywords: form finding, dynamic relaxation, force density, prestress, shell structures