Seismic Response of Soft Storied Building and Secondary System Installed with Semi-Active Dampers

Semi-active hybrid control systems for nonlinear buildings against near-field earthquakes

The seismic response of linearly elastic, four-story asymmetric building installed with various dampers is investigated by numerical simulation study. 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. The peak and root mean square response quantities obtained for the study are: lateral and torsional displacements, lateral and torsional accelerations, base shear, base torque as well as the control forces. The responses are obtained corresponding to the four real earthquake ground motions. The comparative performance is investigated for optimally designed dampers namely, semi-active magneto-rheological dampers, semi-active variable dampers, semi-active variable friction dampers, semi-active variable stiffness dampers and non-linear viscous dampers. The parametric studies are carried out to derive the optimum parameters for various control devices. It is observed that there exits an optimum parameters for various control devices such as to have optimum compromise between lateral-torsional displacement and acceleration response reduction as well as the damper capacity. Further, the implemented control devices are quite effective in reducing the lateral-torsional responses and the effectiveness is more in reducing the torsional responses as compared to the lateral responses.

The seismic response of single-story, one-way asymmetric building with semi-active variable dampers with two-step viscous damping algorithm is investigated. The response is obtained by numerically solving the governing equations of motion. The effects of superstructure eccentricity ratio, uncoupled time period, and uncoupled torsional to lateral frequency ratio are investigated on peak responses of lateral, torsional, and edge displacements and accelerations, as well as damper forces. It is found that the semi-active dampers reduce the lateral-torsional deformations significantly and effects of torsional coupling on effectiveness of control system are more sensitive to variation of eccentricity and torsional to lateral frequency ratio.

The aim of this work is to introduce a new concept for a hydraulic semi-active yaw damper (SAYD) for the improvement of the stability of a high-speed rail vehicle. This concept represents a further elaboration of Secondary Yaw Control but envisages the use of semi-active hydraulic dampers instead of full-active electromechanical dampers, simplifying the design of the system and facilitating the design of a safe and fault tolerant device. Two control algorithms are proposed for the semi-active damper: maximum power point tracking and skyhook with Karnopp approximation. A multi-physics model of the SAYD is introduced and used in co-simulation with a multi-body model of a high-speed vehicle. Using these models, numerical simulations are performed to assess the behaviour of the semi-active damper in terms of improving the running stability of the rail vehicle at very high speed, showing that the use of the SAYD in combination with any of the two control strategies considered allows to improve substantially the stability of the vehicle. The results of experimental investigations performed in the project will be reported in a companion paper.

Magnetorheological (MR) dampers are semi-active control dampers that use MR fluids to provide controllable damping characteristics. MR dampers have proven to be more effective than passive dampers in protecting civil structures during seismic events. While passive dampers have been thoroughly analyzed and understood by researchers, active and semi active dampers are still under investigation by many researchers. MR dampers added protection is achieved by adjusting the damping characteristics of the device so as to minimize structural dynamic loads. Models of the MR dampers highly nonlinear and difficult to adapt for active control, therefore, in this work, the MR damper model presented by Spencer et al will be solved numerically to obtain force-velocity data points. The data obtained from numerical solution of the damper model will be used to construct a linearized state-space model for control purposes. The state space model is obtained via system identification techniques and its agreement with the nonlinear model is discussed.

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Hardik G. Jograna, Devesh P. Soni; Comparative study of semi-active damper systems for liquid storage tanks. AIP Conf. Proc. 27 February 2023; 2427 (1): 020109. https://doi.org/10.1063/5.0101151 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search

Seismic response of submerged secondary systems in base-isolated structures

Building hazard mitigation with piezoelectric friction dampers

The secondary piping systems running along the height of buildings are subjected to significant stresses and accelerations due to the earthquake. Extensive study has been carried out in the past on the seismic response of primary and secondary systems. The effectiveness of the base isolation in minimizing the responses of the secondary piping system for a bidirectional earthquake is evaluated by comparing the responses between the secondary piping system attached to base-isolated and fixed base buildings. Response reduction in the stresses and accelerations developed in the piping system due to the bidirectional earthquake is not widely studied. In this paper, two 3D models of a six-storied building are taken for the study; one is fixed base and the other is base isolated. For the isolation, lead rubber isolators are used. Both buildings connected a secondary piping system, which conveys fluid running along with the height on one side of the building. Both buildings are studied under bidirectional earthquake ground motions with 1:3/4 ground motion ratios. Full interaction between the primary and secondary system is considered. In SAP 2000 the non-linear time history analysis is carried out to evaluate different response quantities of interest at various levels of the PGA. The results of the numerical analysis suggest that the use of a base isolation system in the building gives significant protection to the secondary system. It reduces the peak stresses of the secondary system at critical sections by about 60–70%.

Lateral torsional coupling of asymmetric buildings governs their seismic response. Other than building eccentricity, the extent of this impact depends on the interaction of the building foundation with the surrounding soil – soil–structure interaction (SSI). This study investigates the seismic response of a representative asymmetric building, equipped with semi-active dampers, by accounting for the effect of SSI. Two semi-active damping schemes – friction-type and two-step viscous – are considered and their relative efficiencies are measured when compared with passive dampers. All analyses, including building eccentricity, SSI and dampers, are performed under ten earthquakes with different characteristics and peak intensities. Results obtained imply that SSI can have a significant impact on the lateral torsional coupling of the building if not realistically considered, and thus can greatly influence the seismic response of an asymmetric building. Comparative assessment between semi-active and passive dampers, with respective optimal damping parameters and placement, reveals the superiority of friction-type dampers over the others in reducing the response of the asymmetric building during seismic shaking. Nevertheless, all dampers are found to be efficient in regulating the seismic response of the asymmetric building–SSI system by lowering the adverse effect of lateral torsional coupling on the seismic response of the building.

This paper presents an application of fuzzy logic for response modification of the seismically excited highway bridge benchmark problem. The benchmark problem consists of a three-dimensional, nonlinear model of an isolated two-span continuous prestressed concrete box-girder bridge. The isolation system consists of lead-core rubber seismic isolation bearings combined with semi-active viscous fluid dampers positioned between the bridge deck and end abutments. The dynamics of the semi-active dampers are accounted for via neuro-fuzzy models developed as part of a recent experimental study. The degree of seismic response modification is evaluated via numerical simulations using a supervisory fuzzy logic controller and comparisons are made with respect to sample controllers provided in the benchmark problem statement. The results of this study demonstrate that the supervisory fuzzy logic control algorithm combined with semi-active dampers can offer an effective approach to response modification of seismically isolated highway bridge structures.

The outrigger structural system is one of the most widely used lateral load-resisting structural systems for high-rise buildings. To increase the energy dissipation capacity of the outrigger system, an outrigger damping system has been proposed as a novel energy dissipation system. In this system, the outrigger and perimeter columns are separate and vertical viscous dampers are equipped between the outrigger and perimeter columns. In this study, the control performance of a semi-active outrigger damping system for the seismic protection of a building structure was investigated. Semi-active damping devices, such as magnetorheological (MR) dampers instead of passive dampers, are installed vertically between the outrigger and perimeter columns to achieve large and adaptable energy dissipation. A fuzzy logic control algorithm was used to generate a command voltage sent to the semi-active MR dampers. A genetic algorithm was used to optimize the fuzzy logic controller. An artificial earthquake load was generated for the numerical simulation and a simplified numerical model of a damped outrigger system was developed. Numerical analyses showed that the semi-active damped outrigger system could effectively reduce both the displacement and acceleration responses of the tall buildings compared to a passive outrigger damper system.

The secondary piping systems running along the height of buildings are subjected to significant stresses and accelerations due to the earthquake. Extensive research on the seismic response of primary and secondary systems has been carried out in the past. State of the art review papers on the subjects summarizes those researches. Although the response of the secondary piping system running along with the height of the primary structure like the building has been studied before, the stresses and accelerations developed in the piping system developed due to the bi-directional earthquake are not widely studied. In this paper, a six storied building with a secondary system taken as a pipe running from 1st to 6th story on one side of the building is taken as an illustrative example. A 3-D model of the primary and secondary system is analyzed for bi-directional earthquakes. Considering the full interaction between the primary and secondary structures, the non- linear time history analysis is carried out in SAP 2000 to obtain different response quantities of interest for a PGA level 0.3g with the major to minor ground motion ratio taken as 1:2/3. Response quantities of interest include the maximum accelerations, maximum displacements, and maximum stresses developed at critical sections of the pipe. Also, the floor response spectra are obtained. Results of the numerical study indicate that significant accelerations and stresses are induced in the pipe for a PGA level of 0.3g; the absolute accelerations at the pipe supports vary significantly leading to the generation of large stresses in the pipe.

Seismic Protection of Base-isolated Structures Using Semi-active MR Dampers

Suppressing unwanted vibrations has been a major challenge for more than a century. Semi-active dampers offer a compromise between the high energy costs of active solutions and their increased flexibility. A nonlinear system that utilizes dry friction and piecewise defined contact geometries is used as the basis for a semi-active damper. Furthermore, a slow frequency-based control that does not solely rely on dissipation is considered and compared to the conventional Skyhook Control. Simulations show that the strategy is an effective approach for vibration reduction.