No abstract

An arrangement of tuned mass dampers, termed coupled tuned mass dampers (CTMDs) has been introduced, where a mass is connected by translational springs and viscous dampers in an eccentric manner. The CTMD has coupled modes of lateral and rotational vibration, which have been utilized to control coupled lateral and torsional vibrations of asymmetric buildings. An efficient control strategy has been presented in this context to control displacements as well as acceleration responses of asymmetric buildings having asymmetry in both plan and elevation. The building is idealized as a simplified threedimensional model with two translational and a rotational degrees of freedom for each floor. The principles of rigid body transformation have been incorporated to account for eccentricity between center of mass and center of rigidity. A nondominated sorting genetic algorithm (GA) has been used for solving the multi-objective optimization problem. Tuning of optimum locations of TMDs and their parameters have been done from the multiple pareto-optimal solutions obtained simultaneously. Comparative studies of performance of CTMD with conventional TMDs and bi-directional TMDs have been presented. It has been observed that CTMDs are more effective and robust in controlling coupled lateral and torsional vibrations of asymmetric buildings. The optimal locations have been observed to be reasonably compact and practically implementable for CTMDs.

Summary This paper presents three‐dimensional finite element models for the analysis of square fiber‐reinforced elastomeric isolators (FREI) subjected to cyclic horizontal displacement and constant vertical load. Direction of applied displacement has been varied to evaluate their influence on the isolator performance. Both bonded and un‐bonded boundary conditions at the top and bottom contact surfaces of isolator have been simulated in the analysis. It is observed that the un‐bonded FREI are more effective in seismic isolation as compared with bonded FREI, and stresses developed under lateral displacement are also significantly lower in un‐bonded FREI. Experimental validation has been carried out for un‐bonded isolators and very good agreement is observed in terms of mechanical properties and deformed configuration. In the absence of any close form solution of un‐bonded FREI due to its complex deformation pattern, finite element solution is observed to be sufficiently accurate for arriving at the design parameters of an isolator. Copyright © 2014 John Wiley & Sons, Ltd.

No abstract

Applications of tuned mass damper (TMD) systems for bridge structures are observed for mitigation of problem related to excessive vibration induced by either wind loading or vehicle loading, where dominant modes usually in one direction (commonly vertical) are taken into account. Considering modes dominant in one direction may not be considered as a robust practice while any bridge structure is having dominant modes along both the transverse and vertical directions and the same bridge structure is subjected to loading along both the directions. In the present study, an approach for simultaneous control of major horizontal, vertical and torsional modes is presented targeting robust vibration control under general loading condition. A strategy using modal frequency response function (FRF) is proposed based on the traditional mode-wise control approach. The proposed modal FRF based approach is applied to an existing important large truss bridge (Saraighat Bridge) to carry out an analytical design of TMD system considering general loading conditions. The designed TMD system is found to demonstrate good performance under various white-noise based general loading conditions.