Finite Element Method Model Verification for Bridges, Buildings and other Structures - Construction & Construction Materials

Verification and Validation (V&V) is an enabling methodology for the development of computational models that can be used to make engineering predictions with quantified confidence. Validation in finite element methods (FEM) is the process to check whether the simulation results reflect real world results. In other words, validation is the process of defining the grade to which a model is a precise representation of the real world from the perspective of the projected uses of the model. Verification is the process by which we check that the finite element analysis (FEA) was conducted properly. In other words, verification is the process of defining that a model implementation correctly represents the developer`s conceptual description of the model and its solution. Verification and Validation are processes that cumulate evidence of a finite element model`s correctness and accuracy for a specific scenario.

Once the finite element model is created, the solution process is initiated, which in itself involves solving large number of linear equations, introducing numerical errors at each step. While most of the errors can be neglected, there are errors due to approximations that can lead to FEA malpractices. Hence, it is always better to verify the models and validate FEA results against experimental tests. This requires a finite element solution to provide proper data against which to run experimental validations.

It is essential for engineers to verify the precision of the FEA models and also validate the outcomes against experimental tests, in order to guarantee a final model without an error. Moreover, verification and validation processes are currently required by authorities and industry to reduce time, cost, and risk associated with full-scale testing of bridge structures or any kind of structure.

To find out importance of verification and validation in FEM, it should be mentioned that FEM analysis is approximate, and it is not robust. So, possible errors in modeling, input data and boundary conditions can lead to very big errors in the results. Unfortunately, these errors can be relatively very small and difficult to identify, but they have significant and considerable effect on structure operation and service life.

For instance, using the inappropriate reference temperature for thermal strain in a structural model may simply affect the stresses by a few percent. This error will not be large enough to be noticed when comparing FEA (finite element analysis) results to a hand calculation. However, the error may be more than large enough to change some significant factors/parameters of structure/bridge such as fatigue life. These types of errors are hard to find unless someone is reviewing the analysis very carefully.

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