Abstract
The seismic response of single-storey, one-way asymmetric building with passive and semi-active variable stiffness dampers is investigated. The governing equations of motion are derived based on the mathematical model of asymmetric building. The seismic response of the system is obtained by numerically solving the equations of motion using state-space method under different system parameters. The switching and resetting control laws are considered for the semi-active devices. The important parameters considered are eccentricity ratio of superstructure, uncoupled lateral time period and ratio of uncoupled torsional to lateral frequency. The effects of these parameters are investigated on peak lateral, torsional and edge displacements and accelerations as well as on damper control forces. The comparative performance is investigated for asymmetric building installed with passive stiffness and semi-active stiffness dampers. It is shown that the semi-active stiffness dampers reduce the earthquake-induced displacements and accelerations significantly as compared to passive stiffness dampers. Also, the effects of torsional coupling on effectiveness of passive dampers in reducing displacements and accelerations are found to be more significant to the variation of eccentricity as compared to semi-active stiffness dampers.
Highlights
The asymmetry in buildings may be due to the uneven distribution of mass and/or stiffness of the structural members
The difference between various displacement and acceleration responses of asymmetric and corresponding symmetric system is significantly higher for system installed with passive stiffness damper (PSD) and comparatively very less for the system installed with resetting semi-active stiffness damper (RSASD) and the difference increases with increase in superstructure eccentricity
The effects of torsional coupling are very less for the system installed with RSASDs as compared to PSDs
Summary
The asymmetry in buildings may be due to the uneven distribution of mass and/or stiffness of the structural members. Chi et al (2000) investigated the performance of base isolation and semi-active magnetorheological (MR) damper in asymmetric building and found them very effective for controlling the lateral–torsional responses. Li and Li (2009) investigated the effectiveness of MR damper based on semi-geometric model for asymmetric building and found a greater reduction in displacement and acceleration responses compared to passive control case. Above studies reflect the effectiveness of passive and some of the semiactive systems in controlling the lateral–torsional responses, no specific study has been done to investigate the effectiveness of semi-active stiffness dampers for asymmetric buildings. The effects of torsional coupling on the effectiveness of passive and semi-active stiffness dampers for the asymmetric systems are not studied. The constant coefficient matrices Bd and Ed are the discrete-time counterparts of the matrices B and E and can be written as
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