For steel, the bars are cut if the stress point reaches ultimate stress or if the concrete reaches the separation strain. Contact or collision is detected without any user intervention. Elements are able to separate, contract and/or make contact with other elements. In AEM three contact methods include Corner-to-Face, Edge-to-Edge, and Corner-to-Ground. The spring stiffness in a 2D model can be calculated from the following equations:  Where "d" is the distance between springs, "T" is the thickness of the element, "a" is the length of the representative area, "E" is the Young's modulus, and "G" is the shear modulus of the material. The above equation's indicate that each spring represents the stiffness of an area ("T"·"d") within the length of the studied material. To model reinforcement bars embedded in concrete, a spring is placed inside the element at the location of the bar; the area ("T"·"d") is replaced by the actual cross section area of the reinforcement bar. Similar to modeling embedded steel sections, the area ("T"·"d") may be replaced by the area of the steel section represented by the spring. Although the element motion moves as a rigid body, its internal deformations are represented by the spring deformation around each element. This means the element shape does not change during analysis, but the behavior of assembly of elements is deformable. The two elements are assumed to be connected by only one pair of normal and shear springs. To have a general stiffness matrix, the locations of element and contact springs are assumed in a general position. The stiffness matrix components corresponding to each degree of freedom are determined by assuming a unit displacement in the studied direction and by determining forces at the centroid of each element. The 2D element stiffness matrix size is 6 × 6; the components of the upper left quarter of the stiffness matrix are shown below:  The stiffness matrix depends on the contact spring stiffness and the spring location. The stiffness matrix is for only one pair of contact springs. However, the global stiffness matrix is determined by summing up the stiffness matrices of individual pairs of springs around each element. Consequently, the developed stiffness matrix has total effects from all pairs of springs, according to the stress situation around the element. This technique can be used in both load and displacement control cases. The 3D stiffness matrix may be deduced similarly. The applied element method is currently being used in the following applications: