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Summary: The use of supplemental damping for mitigation of seismic hazard of adjacent building structures is proven to be a practical and efficient way. In developing an efficient damper/energy absorber, shape memory alloy (SMA) material is an excellent candidate due to its well‐known high‐energy dissipation capacity via thermomechanical‐phase transformation. For the first time, the present study focuses on the seismic response control efficiency of superelasticity SMA damper over conventional yield damper, for vibration control of adjacent building structures. To this end, the response of two adjacent steel building frame structures connected with SMA and yield dampers is evaluated through nonlinear dynamic time‐history analysis, under a set of recorded near‐fault ground motions. Optimal characteristics of both dampers are obtained through a parametric study. The robustness of the improved performance of the SMA damper over the yield damper is studied for various characteristic damper strengths, building structures, as well as different scenarios of seismic loading. It is being demonstrated that the superelasticity SMA damper significantly improves the floor displacement control efficiency over the yield damper and also provides a considerable amount of reduction in the peak value of the absolute floor acceleration. [ABSTRACT FROM AUTHOR]

Vibration control of structures under near-fault earthquakes by employing a friction pendulum supplemented with thermally modulated shape memory alloy (SMA) springs as damper system is studied. Temperature modulation of the SMA spring during the earthquake effectively alters its hysteretic energy dissipation capacity and thereby the control efficiency of the isolation system. The response of a structure with the isolation system is evaluated through nonlinear dynamic time-history analysis under a set of recorded near-fault ground motions. Through temperature modulation that effectively yields a large SMA hysteretic energy dissipation, the hybrid friction pendulum system with SMA temperature modulation shows enormous control efficiency. A parametric study reveals that under a wide range of conditions, the thermally modulated SMA friction pendulum isolation system shows improved control efficiency over conventional friction pendulum and SMA friction pendulum isolation systems. Further, the temperature-tuned SMA hysteresis loops substantially suppress the high frequency components of earthquake motions, thus reducing the possibility of damage to the structure. [ABSTRACT FROM AUTHOR]

Tuned liquid column damper (TLCD) is a passive control device for vibration control of structures. Recently, the tuned liquid column ball damper (TLCBD) has been introduced for performance enhancement over the original TLCD. In this paper, the efficiency of the TLCBD is assessed under random earthquake events. The response of a single-degree-of-freedom system with TLCBD is evaluated by stochastic analysis and compared with the TLCD. The study reveals significantly improved performance of TLCBD over TLCD in terms of reducing response of the structure as well as the liquid column. The performance largely hinges on the optimum tuning ratio and the ball-to-tube diameter ratio values, which are proposed herein. The parametric studies establish the performance robustness of the TLCBD under loading and parametric variations. Furthermore, the accuracy of the optimal stochastic responses is verified through deterministic response analysis under recorded seismic motions. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Shape-memory-alloy (SMA) aided isolation bearing has been proposed recently in order to achieve improved performances in several aspects, comparing the traditional bearings for isolation. The behavior of such system has been experimentally demonstrated and numerically simulated under recorded seismic ground motions. The present work deals with the study of optimum performance of SMA-based isolation system under random earthquake. The stochastic response evaluation of the isolated building is performed by nonlinear random vibration analysis via stochastic linearization of load-deformation hysteresis of SMA. The behavior of the stochastic responses indicates the existence of optimal value of transformation strength of SMA to minimize the superstructure acceleration and thereby most efficient isolation. Thus, a stochastic structural optimization problem is taken up in order to obtain the optimal transformation strength. A closed form expression of such optimal parameters are also presented, which may be used for establishing an initial design. The viability of the optimization study is justified by analyzing the response of the optimal system under set of real earthquake ground motion records. The stochastic response behavior of the optimal system is found to be consistent with the responses obtained under real earthquake motions. [ABSTRACT FROM AUTHOR]

ABSTRACT The shape-memory-alloy supplemented rubber bearing (SMARB) has been recently proposed as a superior alternative to traditional elastomeric bearing, such as lead-rubber bearing (LRB), because of the dubious performance of conventional bearings under near-fault earthquakes. The present study establishes the significant improvement of performances in SMARB over the LRB in isolating multi-storeyed building frame against earthquakes. The response of the isolated building is evaluated through nonlinear dynamic time-history analysis under a set of recorded, near-fault, fault-normal component of ground motions. The optimal characteristic strengths for both the bearings are obtained through parametric study. The robustness of the improved performances are studied under varying characteristics of the superstructure, isolation bearing, as well as scenarios of seismic loading. It is demonstrated that the improvement of isolation efficiency, accompanied by considerable reduction of peak and residual bearing displacements can be attained by the SMARB over the LRB. The SMARB is also found to be more effective in suppressing transference of high-frequency components of ground motions to the floor acceleration, which is expected to be beneficial for frequency-sensitive equipment, mounted on the floors. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]