High Performance by Design
IFAS has many distinctive features. For example,
EFFECTIVE LENGTH FACTORS
Effective length factors play an important role in design. There are three methods of determining effective length factors:
1. alignment charts
2. approximate methods
3. theoretical (FE) analysis
The alignment charts were introduced when structural professionals didn't have a computer to analyze the effective length factors. Those charts are for estimate. It is simple, but accuracy is always a problem.
Approximate methods assume a member only depends on the adjacent members. Each adjacent member has a rotational stiffness. Approximate methods replace the adjacent members with rotational springs and then calculate the effective length factors from the isolated member. This approach can provide a good approximation for small and regular structures; for other situations, this approach may fail to provide an acceptable accuracy. The problem is that the assumption made in the beginning is not true for large-scaled or irregular structures. In fact, every pair of effective length factors depend on all the joints, members, and supports.
IFAS uses the theoretical (FE) method to analyze the effective length factors. Each pair of effective length factors are analyzed in the entire structure, not only on a local member as the one assumed in approximate methods. IFAS uses the most accurate finite element formulation, that considers support conditions (settlements, spring constants, or inclined along a line or on a plane), and released joints. Partially rigid effective-length analysis is also available in IFAS.
Analysis of effective length factors is in a nonlinear process. IFAS has an efficient parallel algorithm that not only run highly efficient but also can speed up on multiprocessors. IFAS automatically calculates the theoretical values for designs. With IFAS, structural professionals don't need to assume a length factor and don't need to determine if member is braced or not. IFAS can provide more accurate data from FE analysis and reduces the design cost.
ASYNCHOROUS PARALLEL SOLVERS
IFAS uses parallel solvers and procedures for static, dynamic, and effective length analyses. The parallel solvers are programmed in the analysis kernel. Parallel computing is a trend for scientific and engineering computing, that may distribute the computing streams onto employed processors so as to speed up computations. IFAS not only can run on uniprocessor (or single core) computers but also can speed up on multiprocessors (or multicores).
IFAS is an open system without a predefined limitation on problem size. IFAS has asynchronous parallel solvers for static, dynamic, and effective-length factor analyses. The preprocessor and postprocessor are also capable of parallel visualization.
PARTIALLY RIGID ANALYSIS
IFAS is the first structural package that is capable of partially rigid analysis. The difference between the "traditional analysis" and partially rigid analysis is on the connector. The traditional analysis assumes the connector is either perfect rigid with an infinite stiffness or perfect pin-connected. In most real structures, the connectors are deformable. It is no way to design a connector with infinite stiffness. It can be understood that the traditional analysis makes an assumption that does not exist in most real structures. This is the reason to consider partially rigid connections. Partially rigid analysis takes the connector strength into considerations, and can determine the stiffness a connector requires. Certainly, partially rigid analysis can provide more accurate data to design a more safe structure.