Foundations at the bottom of columns are modeled using one-node, space-frame boundary elements. These elements consist of a [6x6] stiffness matrix with values dependent on the kind of foundation. The user specifies only plane frame terms, i.e., a [3x3] and CIP RC/PT Girder builds an internal [6x6] consistent with the space frame model for the substructure. The torsional term cannot be specified and is therefore infinitely stiff.