Indian Institute of Technology Bombay

About: Indian Institute of Technology Bombay is a education organization based out in Mumbai, India. It is known for research contribution in the topics: Catalysis & Computer science. The organization has 16756 authors who have published 33588 publications receiving 570559 citations.

Optimum parameters of tuned mass damper for damped main system

Abstract: A tuned mass damper (TMD) is a device consisting of small damped spring–mass system attached to a vibrating main system in order to attenuate any undesirable vibrations In this paper, optimum parameters of TMD system attached to a viscously damped single degree-of-freedom main system are derived for various combinations of excitation and response parameters The excitation applied to the main system consists of external force and base acceleration modelled as Gaussian white-noise random process Using numerical searching technique, the optimum damping and tuning frequency ratio of the TMD are obtained for minimization of various mean square responses such as relative displacement, velocity of main mass and force transmitted to the support The optimum parameters of the TMD system and the corresponding response quantities are obtained for different damping ratios of the main system and the mass ratios of the TMD system Explicit formulae for damper damping, tuning frequency and the corresponding minimized response are then derived using curve-fitting technique that can be conveniently used for applications in dynamical systems The error in these expressions is found to be negligible and hence these expressions are convenient for use in damped single degree-of-freedom main system The optimum damping ratio of the TMD is not much influenced by the damping of the main system However, the optimum tuning frequency of TMD is significantly affected by the damping of main system Lastly, a comparison of the optimum damping and tuning frequency of the TMD under filtered white-noise and white-noise excitation is also made Copyright © 2006 John Wiley & Sons, Ltd

Pseudo-dynamic approach of seismic active earth pressure behind retaining wall

Abstract: Knowledge of seismic active earth pressure behind rigid retaining wall is very important in the design of retaining wall in earthquake prone region. Commonly used Mononobe-Okabe method considers pseudo-static approach, which gives the linear distribution of seismic earth pressure in an approximate way. In this paper, the pseudo-dynamic method is used to compute the distribution of seismic active earth pressure on a rigid retaining wall supporting cohesionless backfill in more realistic manner by considering time and phase difference within the backfill. Planar rupture surface is considered in the analysis. Effects of a wide range of parameters like wall friction angle, soil friction angle, shear wave velocity, primary wave velocity and horizontal and vertical seismic accelerations on seismic active earth pressure have been studied. Results are provided in tabular and graphical non-dimensional form with a comparison to pseudo-static method to highlight the realistic non-linearity of seismic active earth pressures distribution.