Application of Dampers in High-Rise Buildings

Abstract

In order to control the vibration response of high rise buildings during seismic events, energy absorbing passive damping devices is most commonly used for energy absorption. Basically a passive damper requires no external energy to function. It dissipates the energy by its own characteristics. Today there are number of types of manufactured dampers available in the market, which uses a variety of materials and designs to obtain various levels of stiffness and damping. Some of this includes viscous, viscoelastic, friction, yielding, tuned liquid and tuned mass dampers. These dampers can be installed in new buildings as well as existing building for retrofit purposes. Effective damping systems can results in higher levels of safety and comfort. The present study is an attempt to understand the behavior of various passive damping systems with principle of working, design issues and their practical applications. The effectiveness of passive dampers installed is studied from two case studies which include their applications in La Gardenia Housing Complex situated at Gurgaon and Taipei 101 Tower which is situated at Taiwan. The seismic mitigation of high-rise buildings using embedded dampers is investigated. Two types of damping mechanisms, i.e. friction and tuned mass dampers are investigated. For design of tuned mass damper mathematical model is illustrated. In addition, a general discussion on the selection criteria and design guidelines are also included in this study. A various methods of analysis of structure embedded with passive dampers are presented. A procedure for computer modeling of tuned mass damper and friction damper is discussed in detail. Finite element models were employed in the analysis using the computer program SAP2000 (Structural Analysis Program) version 14.1. A Fast Nonlinear modal time history Analysis and response spectrum analysis were carried out to obtain the vi damped and undamped responses of the structure. For understanding the behavior of damping systems under various seismic excitations, four different characteristics of earthquake are selected. The earthquake events used in this study are El Centro, Kobe, Northridge and Loma Prieta time histories and response spectra. It has been applied as acceleration time-histories at the base of the structure in the horizontal plane. Concrete material properties were chosen to represent the model, as many high-rise buildings are constructed by using reinforced concrete. A strategy for protecting building from earthquakes is to limit the tip deflection and tip acceleration, which provides an overall assessment of the seismic response of the structure. Several medium and high-rise building structures with embedded friction dampers and tuned mass damper were studied subjected to different earthquake loadings. The change in response of building due to dynamic force is studied for controlled and uncontrolled buildings. The efficiency of energy dissipating dampers for vibration control of structure was investigated for five different placements of dampers and to study the influence of location on the seismic response. The results of analysis is compiled in form of displacement, acceleration, storey drift, time period, frequency, energy dissipation capacity of dampers and compared with uncontrolled structures. Comparison between tuned mass damper and friction damper is also carried out to demonstrate the feasibility of the technique for seismic mitigation of the structure for medium and high-rise buildings. Results also provide the information which can be used for optimal damper placement for reducing the maximum seismic response. This study has investigated the use of friction damper and tuned mass damper to mitigate the seismic input energy within medium and high-rise structures. These damping devices were embedded in a variety of different placement (one at a time). The appropriate damper for reducing the seismic response of structure is finding out vii for medium and high-rise structure. Parametric study is carried out by varying location and type of damper. Results from this study indicates that the performance of friction damper and tuned mass damper are dependent on the characteristics of earthquake ground motion and both are quite effective in reducing the structural dynamic response in the form of acceleration, displacement and storey drift. Friction dampers are most effective when placed close to regions of maximum storey drift, while the best performance of tuned mass damper was achieved when placed at top storey. Tuned mass damper gives the significant performance with increasing the height of structure, while friction damper gives incredible performance for medium-rise structures. So for high-rise structure tuned mass damper is preferred and medium-rise structure friction damper should be used. It is possible to achieve seismic mitigation, under all earthquake excitations, for all the structures considered in this study, by using appropriate damper types suitably located within the structure.