Analytical and Experimental Investigation on Frequency Dependent Linear Control Algorithm for Performance Enhancement of Real Life Civil Structures under Random Excitation

Civil Engineering
Project type: 
Sponsored Projects
2019 - 2021
Principal Investigator: 
Dr. Sanjukta Chakraborty
Project Number: 
Sponsoring Agency: 
SERB - Start-Up Research Grant (SRG)
Total Budget: 
This proposal deals with the development of a robust frequency dependent linear optimal adaptive control algorithm aimed at response control of a structural system at a minimum input effort while subjected to an external excitation. Civil structures attract severe force during strong intensity earthquake or strong wind excitations which belong to different frequency ranges. Additionally, the natural frequency of the structure influencing the dynamic response may also vary depending on the change in the structural property such as variation in mass condition, or stiffness degradation. Different dynamic system parameters such as inertia, stiffness and damping are sensitive to different frequency regimes of excitation, defined by the ratio of the external excitation frequency to the natural frequency of the structure. The design of a control mechanism applied to any structure should depend on the frequency regime of excitation as well as the sensitivity of the structural parameter at that frequency regime. Therefore, the essential characteristics of a frequency dependent linear adaptive control algorithm are the following:
1. Depending upon the frequency regime of excitation, the control force should be adapted in a way that the relevant structural parameter sensitive at that particular regime of excitation should be influenced.
2. In case of an excitation regime where the structural parameters are strong enough to control the excitation, and the control force has no significant influence, the control force should become minimum.
By achieving these characteristics, the structural response can be controlled at all the frequency regimes and at the same time if some perturbation in the initially assumed property takes place, the control force can adapt to provide the desired effect at a shifted set of frequency regime. Further an efficient use of control force to all the frequency regimes enables to reduce the control force significantly. In this work, a combination of classical and modern feedback control theory is adopted to obtain the desired form of control input first. As an initial part of the work, an algorithm has been developed though the efficiency is seen only at a high frequency regime of excitation. For obtaining the desired control effect, the work is organized in the following steps
a) Development of a frequency dependent control algorithm to provide an efficient control action to all the frequency regimes of excitation
b) Experimental investigation including the effect of time delay and system perturbation
c) The effect of the applied control spillover to the structural modes unintended to control
d) Invention of a passive or a semi active device for the widespread application of the developed algorithm to the real life civil structures.