ABSTRACT
While there are numerous design guidelines for oscillations of floors, staircases have received comparatively less attention. Dynamic testing of existing staircases can improve understanding of their behaviour and lead to more accurate methods for predicting accelerations in service. This study uses a smartphone device to measure oscillations of a helical staircase. The smartphone accelerometer’s output was compared to the output of a laboratory accelerometer and in the range of frequencies relevant to this study the differences were negligible. A helical staircase was tested in heel drop and walking tests to find natural frequencies and damping of a staircase. Computer analysis results for natural frequencies were in good correlation with the measured data. The results of footfall analysis showed that despite a relatively high fundamental frequency of the staircase, its response factor exceeded the one prescribed by the design guidelines. Footfall analysis results depend critically on the correct estimate of the damping ratio. The actual damping ratio was found to be higher than the one in guidance documents.
