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A new active tuned liquid column damper is developed for seismic vibration control of structures by employing the configuration of the compliant liquid column damper (CLCD). This control system is referred to as the active CLCD or ACLCD. The theoretical model of the proposed ACLCD is presented, in which the controller is designed first by the linear quadratic regulator (LQR) algorithm. The design procedure developed for the ACLCD is illustrated both for an example flexible structure and for an example stiff structure, subjected to a recorded accelerogram input. The optimal design of the passive CLCDs is also presented, to provide the basis for the choice of the damper parameters of the ACLCD. The optimum control parameters of the ACLCD are evaluated with the objective of minimizing the displacement response of the structure while maintaining the stability of response reduction and satisfying the constraints on peak liquid and whole damper displacements. A multiresolutionbased wavelet controller (WLQR) is also designed for the ACLCD, achieving structural displacement response reductions comparable to that obtained from the conventional LQR controller but with the application of comparatively lower control forces. The enhanced effectiveness of the ACLCD over that of the passive CLCD is demonstrated through a time domain study. The performances of the LQR-and WLQR-based control strategies are compared, in terms of both structural response reduction and requirement of peak control force magnitudes, for the design input as well as under excitation variability.

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The post-earthquake function of elevated water tank structures so as respond to the civil water requirements is of extreme significance. These structures are, however, extremely vulnerable to seismic conditions and there has been substantial damage/failure of several such structures during major earthquakes. A review of the damage and performance of some elevated water tanks subjected to earthquakes is presented in this paper. An investigation is also made on the seismic vibration control of elevated water tank structures by using Tuned Liquid Dampers (TLDs). A frequency domain formulation for the transfer function of the elevated water tank with attached TLDs is developed. Numerical studies on a reinforced concrete elevated water tank with shaft type support are carried out. The effect of detuning on the performance of the TLDs due to the change in the structural frequencies resulting from the fluctuating water level in the water tank is also examined. Results indicate that it is possible to design a fairly robust and effective TLD system for the seismic vibration mitigation of the considered elevated water tank.

The paucity of space and requirements of building infrastructure has driven us to explore for taller building systems. Also a large number of construction materials has emerged and are being used extensively in buildings. The usage of light weight high strength materials reduces the space requirement and also becomes economical. However, such structures have structurally become susceptible to the lateral loading generated due to wind or earthquake. Attempts are made to control the response of tall building systems by introducing control mechanisms in the form of active, passive or hybrid system. Usage of liquid storage tanks in tall building system in the form of a passive control device proves effective. Several works have been carried out in the past to understand the efficacy of such system, which popularly is known as tuned liquid dampers or tuned sloshing dampers (TSD). The present paper deals with the development of a numerical code to demonstrate the efficacy of such tuned sloshing damper considering fluid structure interaction effect.