Roy Denoon

Full-scale damping measurements of structures in Australia

Abstract Full-scale damping measurements were performed upon three classes of civil engineering structures including free-standing lattice towers, reinforced concrete buildings and pedestrian footbridges. Most of these structures were subjected to forced vibration tests to obtain structural damping estimates. Autocorrelation and random decrement procedures were used to extract total damping from load-induced resonant response signals. Both these procedures were further scrutinised in light of the measured results. A simplified analytical expression for aerodynamic damping was derived. Some damping predictors were proposed based upon the findings of this paper.

Full-scale measurements of wind-induced response of an 84 m high concrete control tower

Abstract This paper details the development of an instrumentation system for the measurement of the wind-induced dynamic response of structures. It was installed on an 84 m high concrete control tower of circular cross-section. Twelve months of data measured at the tower are presented and it is demonstrated that the accelerations experienced exceed serviceability criteria for human comfort. The effects of differing incident turbulence regimes are investigated and are found to have no significant effect on the dynamic response of the tower. The first and second mode natural frequencies were measured as 0.39 and 2.62 Hz, respectively. The structural damping of the tower was estimated to be 0.8 %. The mode shape of the tower was closely approximated by a power law with an exponent of 1.6.