Evaluation of a finite element model for dynamic characteristic prediction of a stadium facility

The application of dynamic analysis to assembly structures has only recently been implemented to address vibration serviceability concerns and the possibility of dynamic over-loading. These issues are not always adequately addressed by minimum static design loads recommended by building codes, particularly when resonance or near resonance due to the dynamic load is likely. One structure type that is regularly subjected to large dynamic loads is a stadium facility grandstand. The Midland Road stand at the Bradford and Bingley stadium facility in West Yorkshire, England, was recently the subject of experimental modal analysis and remote monitoring during sporting events. This experimental modal analysis generated information about in-service behavior of the structure but a method is required to reasonably predict this behavior prior to construction. With a reasonable prediction of behavior prior to construction, a design can be assessed with respect to vibration serviceability criteria and dynamic overloading and modified if necessary. Several finite element modeling programs offer a method of modal analysis within the software package. These programs can simulate the motion of the structure and generate modal parameters based on the structural model input by the engineer. Software packages, such as SAP2000, STAAD and RAM, are very commonly found in structural engineering firms and would be the primary means used to perform a dynamic analysis on a structure to predict its behavior. A comparison of the modal parameters and motion predicted by a finite element model of the grandstand at Bradford and Bingley stadium to the data collected in field measurements is presented. This type of comparison is useful in understanding the particulars of creating a representative dynamic model and will illustrate the accuracy and challenges that might be expected from a finite element analysis.