Analysis and design of building structures with supplemental lead dampers under earthquake and wind loads
Thesis DisciplineCivil Engineering
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
This research is carried out to investigate the dynamic behaviour of a 12-storey reinforced concrete framed structure with recently developed lead-shear dampers such as the Penguin Vibration Dampers under earthquake and wind loadings.
For regular framed structures under earthquake excitations, a satisfactory distribution of damper yield strengths in the storeys has been found using the criteria of minimising interstorey drift, base shear and cost of the dampers. The displacement, acceleration and the interstorey drift responses for the structure with supplemental dampers can be reduced significantly. Pushover analyses of the structure with supplemental dampers have been performed and the results have been compared with that of the structure without dampers. Equivalent SDOF system for the MDOF structure with dampers has been obtained through appropriate transformation by means of displacement shape of the structure at the target displacement. For such a distribution of the dampers, the structure with supplemental dampers will behave predominantly in its first mode. The equivalent SDOF system can be used to predict the response of the MDOF structure with dampers with good accuracy. A simplified nonlinear static method, taking into account the effect of the supplemental dampers, has been investigated to conduct the seismic analysis of the structure with dampers. While comparing with the nonlinear time history analysis method, it has been found that this simplified method can give a very good approximation to the response. By investigating the effects on the displacement and acceleration response associated with the supplemental dampers under earthquake excitations, optimal damping levels of the dampers have been found. Based on the simplified nonlinear static method and the optimal damping ratio of the dampers, a displacement-based design procedure has been established to determine the damper yield strengths in the storeys for preliminary seismic design.
Time-domain analyses of the structure with supplemental lead dampers have been performed using the artificial wind time history that was simulated by means of an equivalent wind spectrum technique. The effects of the dampers on the structural displacement response are not as significant as on the acceleration response for wind loading. For structures under the serviceability Limit State subject to wind loading, the acceleration response is the main concern. Considerable benefit can be gained by incorporating the dampers into the structures.