Seismic Response Control of A Building Using Passive Devices

Abstract

Earthquake is one of the major natural hazards to life on the earth and have affected people and structure of every continent. The damaged caused by earthquake is mostly associated with man mad structures. Hundreds of earthquakes (small or big) are a ecting regularly acroses the world and hence, it is necessary that structures should be designed to resist earthquake forces, so as it reduces the loss of lives. Three basic technologies are currently in practice to protect buildings from damaging earthquake e ects. These are Base Isolation, Passive Energy Dissipation Devices and Active Control Devices. In passive energy dissipation systems the motion of structure is controlled by adding devices which modi es sti ness, damping or both. Passive energy dissipation devices are found e ective against winds and earthquake induced motion, and operates on principles such as, yielding of metals, frictional sliding and deformation of viscoelastic (VE) solids or uids. The present study is an attempt to understand the behavior of passive energy dissipation devices and its e ectiveness in response reduction under di erent types of excitation. The work composed of characterizing passive devices, like Viscous, Viscoelastic (VE), and Metallic Yield dampers, under sinusoidal motion and random earthquake excitations through commercially available tool MATLAB. Earthquake events used in this studies are El Centro(1940), Loma Prieta (1989), Northridge (1994), and Kobe (1995) time histories. A three storey shear building has been considered to nd out the e ectiveness of various passive dampers. Lump mass model is adopted in order to obtain, mass matrix and sti ness matrix. Damping is assumed to be Rayleigh's damping and damping matrix is determined considering 5 % critical damping coe cient for all modes. Equation of motion for multi degree of freedom system with passive devices are derived. These equations are solved using numerical method like Newmark-Beta for building without passive device, i.e,. uncontrolled and with passive devices, i.e,. controlled building under the di erent earthquake excitations through MATLAB. Response quantities like displacement, velocity, acceleration, inter storey vi drift and damper force have been extracted for uncontrolled and controlled building. The response quantities of uncontrolled building have been compared with the controlled building in order to establish it's e ectiveness. Parametric study of three storey building equipped with viscous and viscoelastic damper have been carried out, by changing the damping co-e cient and required damping ratio respectively. Results indicate that extra amount of damping and sti - ness provided by di erent passive damper directly in uence the responses by reducing it. From the study, it can be reveals that all the response quantities like maximum displacement, maximum velocity, maximum acceleration and maximum inter storey drift are reduces by half as compare to uncontrolled building. It has been found that, viscous damper are more e ective under the Northridge type of earthquake excitations, however viscoelastic and ADAS damper are suitable for Loma Prieta type of earthquake excitations.