IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308 __________________________________________________________________________________________ IC-RICE Conference Issue | Nov-2013, Available @ http://www.ijret.org 6 APPLICATIONS OF DAMPERS FOR VIBRATION CONTROL OF STRUCTURES: AN OVERVIEW Vajreshwari Umachagi 1 , Katta Venkataramana 2 , G. R. Reddy 3 , Rajeev Verma 4 1, 2 Department of Civil Engineering, NITK, Surathkal 575025 3, 4 Structural & Seismic Engg Section, Reaction Safety Division, BARC, Trombay, Mumbai-400085 vmumachagi@gmail.com, ven.nitk@gmail.com, rssred@ barc.gov.in, rajeev_ballia@yahoo.co.in Abstract Dampers have become more popular recently for vibration control of structures, because of their safe, effective and economical design. This paper presents an overview of literature related to the behavior of dampers on seismically affected structures. The review includes different types of dampers like metallic dampers, viscoelastic dampers, frictional dampers etc. Keywords: Seismic response, dampers, structural control systems. -----------------------------------------------------------------------***--------------------------------------------------------------------- 1. INTRODUCTION Over the past few decades world has experienced numerous devastating earthquakes, resulting in increased loss of human life due to collapse of buildings and severe structural damages. Occurrence of such damages during earthquakes clearly demonstrates the high seismic hazards and the structures like residential buildings, lifeline structures, historical structures and industrial structures need to be designed very carefully to protect from earthquakes. Structural design approach using seismic response control is now widely accepted and frequently applied in Civil Engineering. In recent years, much attention has been paid to the research and development of structural control techniques such as passive control system, active control system, and semi active control system giving special importance on improvement of wind and seismic responses of buildings and bridges. Passive control systems do not require any power supply. Active control systems require external power supply and operate based on sensors which are attached within the structures. Semi active control systems are combination of both passive and active control systems which require external power supply and they operate based on sensors attached to within the structures. But when there is no power supply, passive control systems control the vibration of structures. Both control systems can be used for strong wind motion and earthquakes. Serious efforts have been undertaken to develop the structural control concept into a workable technology and such devices are installed in structures. 2. LITERATURE REVIEW Structural control systems increase the energy dissipation capacity of structures during an earthquake by converting mechanical energy into heat energy. Different kinds of energy dissipation systems are given below: Tuned Mass Dampers (TMDs): Tuned mass dampers (TMDs) are as shown in Fig.1 (Chakraborty and Roy, 2011 [1]) comprising a mass, spring attached to the structure and are used for vibration control of structures when subjected to earthquake excitations. It is a frequency dependent device. Recently, much research has been carried out such as analytical, numerical, experimental and optimum solutions of structures to study the effectiveness of TMDs in reduction of seismic response of structures. The passive tuned mass damper (PTMD) was developed and implemented by Lin et al., 1999 [2] for seismic reduction of irregular buildings. Here, five real earthquakes were considered for numerical and statistical analysis of five storeys torsionally coupled building. Results demonstrate that PTMD effectively reduces the response on building during earthquake. Zuo et al., 2004 [3] have developed multi degree of freedom tuned mass damper. To obtain the optimal solution experiments were conducted sequentially to optimize the two degrees of freedom system. TMD can be tuned to damp the first two flexural modes of a free-free beam. Pinkaew et al., 2003 [4] have reported that structure with tuned mass damper was less effective for seismic damage reduction. Peter, 2006 [5] has discussed the theoretical and experimental studies on tuned mass damper for the seismic retrofitting of existing structures. Almazan et al., 2007 [6] have observed that new bidirectional and homogenous tuned mass dampers are very effective in reducing the seismic response of structures. Marano et al., 2007 [7] have proposed a linear tuned mass damper for seismic control of structures by using constrained reliability based on optimization technique. Further, Marano et al., 2010 [8] have investigated the optimum parameter of tuned mass damper for minimization of displacement of the structure. From the results it was concluded that the design variable mass of the TMD considered was more capable compared to the solutions obtained without it.