Seismic retrofit of reinforced concrete structures using magnetorheological mass driver: Evolving a design methodology

Abstract

This paper proposes a design methodology for a damping enhancement-based seismic retrofitting of a damaged reinforced concrete (RC) model frame with a mass driver (MD) and magnetorheological (MR) damper. The MR-MD is applied with preset constant current inputs and the structure + MR-MD system is subjected to harmonic and seismic base excitations. Equivalent effective damping for a biviscous MR damper is derived both from energy and secant damping considerations. The effect of yielding force of the MR damper, mass value of the secondary system, and non-linearity associated with input accelerations are discussed. The paper proposes a suboptimum frequency tuning, that is, the frequency of the secondary MR-MD is marginally lower than the optimum value, anticipating a degrading stiffness and frequency drop of the target structure, typical of materials like masonry and concrete. Experimental investigations with undertuned, overtuned, and near-optimum tuned conditions of the secondary MR-MD system are performed to highlight that operation with near optimum damping plays a significant role, particularly when MR dampers are used.Higher effective damping associated with higher preset current inputs have a tendency to be counter-productive, which is proved experimentally and analytically. Four seismic performance parameters are calculated, which showed a substantial reduction of acceleration and displacement responses on the experimental structure when the damper is operated at lower input currents. From analytical and experimental investigations, a simplified retrofit design methodology for a degraded RC superstructure is proposed and experimentally validated through incorporating a mass driver coupled with a non-linear damper. KEYWORDS design methodology, mass driver, MR damper, MR-TMD, TMD retrofit, tuned mass damper Struct Control Health Monit. 2019;26:e2353.wileyonlinelibrary.com/journal/stc

A novel servomechanism based proportional–integral controller with Kalman filter estimator for seismic response control of structures using magneto‐rheological dampers

“…This study presents a detailed comparison between proposed PI and conventional P-controller (commonly used as H 2 /LQG optimal controller 11,13 ) in terms of variation in structural responses and control force. The controller gain for P-controller is obtained by making the integral gain, K i ¼ 0 in Equation (23). The linear gains in Equation ( 23), that is, K p , K i , and L are estimated as described in the following sections.…”

“…In addition, different advance control schemes are also formulated by researchers to actuate semi-active devices such as MR-tuned liquid column damper (MR-TLD), 21 braced hydraulic damper system, 22 and MR mass driver. 23 The merger of active and semi-active control strategies is an interesting new approach in this field of research. Yanik and Aldemir 24 presented an integrated control algorithm for the better synchronization between active tendon and MR damper systems during seismic events.…”