AN INVESTIGATION OF HUMAN INDUCED VIBRATIONS ON CLEMSON MEMORIAL STADIUM

Human induced stadium vibrations have become of increasing concern to design engineers and facility managers as more energetic crowds and increasingly efficient structures have increased the likelihood of serviceability issues. The \u27in-time\u27 bouncing of spectators due to music has caused one such issue in the south upper deck of Clemson University\u27s Memorial Stadium. To gain an understanding of the severity of vibrations in Memorial Stadium, a combination of experimental and analytical modeling is utilized. Data collected by an array of accelerometers installed on a main post tensioned precast cantilever girder provides a season and a half of response histories in various states of occupancy and excitation. Utilizing data obtained due to ambient vibrations, the Enhanced Frequency Domain Decomposition (EFDD) methodology is used to extract modal properties including frequencies, mode shapes, and modal damping at various levels of occupancy. A finite element model of the girder, initially created utilizing structural drawings and design level properties for an empty stadium, is calibrated using the dynamic characteristics of the empty stadium. This process is carried out considering the first three modes. The calibrated model can be used to analyze various crowd loading scenarios including passive, active, and harmonic loadings with known responses and unknown responses. Comparing the results of the FE model to relevant data sets shows the EFDD method in combination with ambient vibration data to be an effective means of analyzing a large structure that would have otherwise been difficult to analyze by traditional forced vibration techniques. The calibrated model provides a benchmark for future health monitoring or performance studies