Our structural dynamic simulations and the MARS computer code are formulated with an object oriented approach. All entities of the structural model are treated as objects. Each component, which is treated like an object, includes properties used in its definition, a list of homogenous elements, and references to other objects, such as materials. Inheritance and polymorphism are consistently implemented. For example, a quadrilateral face is defined by four points. A quadrilateral shell inherits all properties and methods of a quad face. Thus, the method for calculating the cross sectional area (or the normal) of a quad face is also employed by the quad shell, and needs be defined only once.

Polymorphism is also widely implemented: for example tasks like input, calculate internal forces, generate plot data, etc, are common to all components.

The object-oriented architecture has several implications. For example, materials are not identified with physical components. Thus, if several distinct components (even of different types--shell, solid, beam--employ the same type of steel) then only one instance of that steel is necessary and all components refer to that instance. At the same time, if a multi-layered shell employs different materials for its layers, it can do so since each layer can refer to the material from which it is made. Dimensional properties (such as shell thickness or beam cross section) and physical quantities (such as hourglass control parameters) are associated to components rather than materials.