“Computational Civil Engineering - "Intersections" International Journal

204 M. Petrina, Roxana BalcThe element stiffness matrix was calculated for the model of the element sconnected with the elastic springs by the rigid nodes with finite dimensions.Input dataINPUT.EXEInput data fileCADRE.EXEOutputdata fileOutputresults fileDiagramsFigure 1. Operating procedure of the programThe stiffness element matrix should by first formed, transformed and assembled toform the stiffness matrix for the global structure from which the displacements aresolved. They will be used for the calculation of the element efforts.The structure stiffness matrix was assembled and then transformed in a band matrixusing the band-width technique. The maximum band width for the structurestiffness matrix is calculated, and making use of the symmetry, only a half ofstiffness matrix is stored. A nxn dimension stiffness matrix can be stored in a nxhrectangular matrix, in which h is the band width.The matrix equation may be arranged by separating the unknown nodesdisplacements (1)⎧A⎨⎩ADSRS⎫ ⎡ K⎬ = ⎢⎭ ⎣KDRDKKDRR⎤⎧Z⎥⎨R⎦⎩DS⎫⎬⎭(1)Where,DA Sis the vector of external loads applied of the nodes structure on thedegree of elastic freedom directions;A is the vector of external loads applied on the frame nodes on the direction ofRSsupports;