Earthquake resistant visco-elastic energy dissipator link elements
The visco-elastic* (help in dissipating large amount of seismic energy) link elements have been made-up of "ply" of used/old radial rubber tyres of passenger cars. It contains two layers of textile belt as well as two layers of steel belts along-with steel wires embedded diagonally in the rubber that enhance stability, strength and visco-elastic property of the material. Moreover, eminence inherent properties of radial tyres such as high tear resistance, high shear resistance and high toughness can be used more effectively for the development of visco-elastic energy dissipator links which can withstand under extreme earthquake forces. "Viscous property of the material is used to increase damping and elastic property of the material to regain the size and original position of the structural member after removal of the applied load. In other words material used to absorb some of the applied energy and dissipate rest of the energy"
A Seismic Vibration Damping Assembly and System
Open ground floor is a common feature in multistory buildings. This provides easy access to the spaces within to be used for vehicle parking and/or community gatherings. However, these open spaces also introduce vertical irregularity causing severe distress in the columns during earthquake ground motions. A friction damper has been designed and tested to absorb the excess energy during earthquake induced vibrations while allowing the access to open spaces without any obstruction. These dampers have been tested for the maximum considered earthquake (MCE) for the most severe zone (Zone-V) of India and the seismic demand on the columns has been found to reduce by approximately 50% under the test conditions. This damper assembly can be easily deployed in existing structures as well by virtue of its unique clamp-on design. Incorporation of this damper assembly will lead to enhanced seismic resilience while reducing overall costs of providing a safer open ground floor.
A System and Method for Seismic Response Control
A sliding mass floor system is designed and developed to control the seismic response of structures. A number of small mass units, called secondary system, are arranged on a floor with suitable spring attachments to the anchor blocks driving reaction from the floor. The total mass of these small mass units is kept around 10% of the seismic mass of the floor and the spring stiffness is kept so as to have the natural frequency of the smaller mass-spring oscillators in the range of 0.5 to 0.9 times the natural frequency of the mode of vibration of the structure which is required to be controlled at that floor. A reduction in seismic response of main structure by approximately 50% has been observed under test conditions for the maximum considered earthquake (MCE) for the most severe zone (Zone-V) of India. The proposed system can also be used for retrofitting of existing structures without any compromise on the functional requirements and enhance seismic resilience of structures at a much lower cost.