| The development of finite element analysis program named SNAPS3D (Seismic Nonlinear Analysis of Precast Structures) for nonlinear analysis of precast concrete structures under seismic loads is described. The advantages of the Microsoft .NET Framework and C# programming language, which are used to develop to source code, over traditional procedure-based FORTRAN finite elements in terms of maintainability and extensibility of software is discussed. Since NET Framework does not contain out-of-the-box numerical libraries, the classes for matrix and vector operations are developed and packaged in an assembly named Snaps3D.Algebra. The finite element concepts such as nodes, elements, solvers, and loads are abstracted into C# types (classes and interfaces) and packaged in an assembly named Snaps3D.Core. Included in this assembly are specialized classes to model precast concrete members (shell element to model wall panels and floors, beam element to model beams, columns, and horizontal connections) and their behavior (elastic material to model the response of precast members and nonlinear materials to model the connections). New material models, elements, solvers can be developed and incorporated into the program either by implementing the appropriate interface (IElement interface to add a new element class) or by inheriting from an existing class with similar behavior (Inherit from Solid class to develop Shell element). Neither case would require the existing program to be modified. The program is used to solve several example problems to verify its operation and to demonstrate how precast building components can be modeled using the element and matrix classes that are currently implemented in SNAPS3D. |
