Pre-processing parallel and orthogonally positioned structural design elements to be used within the finite element method

Two methods for pre-processing of (parallel and orthogonal positioned) structural design elements, to be used for specifying kinematically undetermined behaviour within the finite element method, are presented. One method is based on first checking line–line combinations, using a (2D) projection technique, followed by investigating line–area combinations employing a line–line combination related technique. These procedures (line–line and line–area) are repeated until convergence occurs. The method is finalised by pattern recognition to find all new areas within the original areas. The second method is also based on (iteratively) checking line–line combinations and line–area combinations but now line–line combinations are studied using a line–area intersection technique and line–area combinations are investigated with a technique that makes (expensive) pattern recognition superfluous. Both methods are implemented in C++ and are compared for correctness and efficiency by using academic and building design examples. It can be concluded that the second method seems an appropriate candidate for further implementation.