Papers by Dr. R. S. Jangid
Seismic response of asymmetric buildings with semi-active friction dampers
Response of wind-excited benchmark building installed with dampers
The Structural Design of Tall and Special Buildings, 2009
ABSTRACT The response of the benchmark building is investigated under across-wind loads. The gove... more ABSTRACT The response of the benchmark building is investigated under across-wind loads. The governing equations of motion are solved by employing state space theory. Generally, the dampers are connected to successive floors of a building (Type-I arrangement). As the relative velocity and inter-storey drift between the alternate floors would be larger, the performance of dampers is studied by connecting them to alternate stories with two innovative (Type-II and Type-III) arrangements, and the comparison of response is made with that of the conventional (Type-I) arrangement. Optimization of location and number of dampers is also carried out with the help of a controllability index, which is obtained with the help of root-mean-square value of the inter-storey drift. Further, a parametric study of semi-active variable friction dampers and linear viscous dampers by varying gain multiplier and damping ratio, respectively, is carried out. From the numerical study, it is observed that Type-II and Type-III arrangements are found to be quite effective in reducing the response quantities. It is also found that a considerable amount of economy is achieved by optimization of location of dampers. Copyright © 2009 John Wiley & Sons, Ltd.
Strength prediction of a bottle-shaped strut for evaluating the shear capacity of reinforced concrete deep beam
Engineering Research Express
For the analysis and design of reinforced concrete (RC) deep beams, the strut-and-tie model is ty... more For the analysis and design of reinforced concrete (RC) deep beams, the strut-and-tie model is typically employed to simulate the flow of stresses. A bottle-shaped strut develops between the loading point and support, in which compressive stress spreads laterally and induces tensile strain in the transverse direction, which reduces the compressive strength of the strut significantly. Web reinforcements are provided in deep RC beams to prevent splitting of the diagonal strut due to the presence of these transverse strains. In this article, a simplified design procedure based on the strut-and-tie model (STM) is proposed for the evaluation of the shear capacity of deep beams with web reinforcement. The suggested model is based on modified compression field theory and considers the impact of shear reinforcement ratio, transverse tensile strain, post-cracking strength of concrete, and the actual dispersion of compressive stress based on strut geometry (aspect ratio) for strength predicti...
Optimization of MR Dampers for Wind-Excited Benchmark Tall Building
Practice Periodical on Structural Design and Construction
Optimum Parameters of Tuned Inerter Damper for Damped Structures
Journal of Sound and Vibration
Optimum parameters and performance of negative stiffness and inerter based dampers for base-isolated structures
Bulletin of Earthquake Engineering
Novel combinations of true negative stiffness dampers (NSDs) and inerter devices are used concurr... more Novel combinations of true negative stiffness dampers (NSDs) and inerter devices are used concurrently as supplemental dampers for response control of base-isolated structures. The combination of the inerter and NSD is denoted as negative stiffness inerter damper (NSID). Classical H∞ optimisation based on a well-known fixed-point theory of tuned mass dampers is used to derive optimal parameters for NSD and three configurations of NSIDs. Optimal NSIDs and NSD are supplemented to the base-isolated structure as passive control devices. The closed-form expressions for optimal parameters are derived, which will be useful for the initial design process of these devices for isolated structures. A numerical searching technique is used to verify the derived closed-form expressions for the optimal parameters of NSIDs. A comparative analysis is also run by utilising three configurations of NSIDs and a true NSD as supplemental control devices to the flexible base-isolated structure. The governing equations of motion are written in state-space form, and the performance of the proposed supplemental dampers for the base-isolated structure is investigated under real earthquake records. Time history analysis shows that the optimal NSIDs and NSD effectively control the objective variables of base displacement, inter-storey drift, and top storey acceleration. Especially under near-fault, which may bring isolation systems to critical working conditions, the proposed supplemental dampers cushion against failure by improving energy dissipation capacity compared to conventional passive dampers. Optimal NSID parameters are lower in magnitude than NSD parameters, resulting in a smaller damper size, which is desirable from a practical design standpoint.
Comparative Performance of Isolation Systems for Benchmark Cable-stayed Bridge
International Journal of Applied Science and Engineering, 2008
Seismic Performance Assessment of Clutching Inerter Damper for Isolated Bridges
Practice Periodical on Structural Design and Construction, 2022
Frontiers in Built Environment, 2021
Passive energy dissipation devices or supplemental damping devices have been successfully impleme... more Passive energy dissipation devices or supplemental damping devices have been successfully implemented into structures for controlling the excessive vibrations under wind and seismic excitation. Recent developments in the form of negative stiffness dampers (NSDs) and inerter-based vibration absorbers (IVAs) as potential energy dissipation devices are of considerable interest to researchers. The present study evaluates the performance of the combined NSD and IVA as a possible alternative to the traditional energy dissipation devices such as viscous dampers (VDs) and viscoelastic dampers (VEDs). The mathematical formulation and optimal design of the combined NSD and IVA mechanism are presented. A 20-storey benchmark building is modeled as a multi-degree-of-freedom (MDOF) shear building. The dynamic equations for the MDOF building are written in the state-space form, and a simple optimization approach based on effective modal damping is prescribed. Comparative performance between tradit...
International Journal of Applied Science and Engineering, 2010
A modified friction damper is presented to enhance the performance of conventional friction dampe... more A modified friction damper is presented to enhance the performance of conventional friction damper and semi-active variable friction damper. An additional plate is provided be- tween the two sliding plates of a conventional friction damper which results in an additional sliding interface with the same normal (clamping) force. Similar modification is also made to semi-active variable friction damper (SAVFD) to enhance its performance. The enhancement in the performance of the benchmark building is studied under across wind loads by installing the modified dampers. The governing equations of motion are solved by employing state space the- ory. Optimization of location and number of dampers is also carried out with the help of a con- trollability index which is obtained with the help of root-mean-square (RMS) value of the in- ter-storey drift. Further, a parametric study of passive friction dampers by varying slip force is carried out. From the numerical study, it is found that both do...
Development and analysis of passive hybrid energy dissipation system for steel moment resisting frame
International Journal of Civil and Structural Engineering, 2015
A passive hybrid energy dissipation system (PHEDS) consists of rate dependent devices in series w... more A passive hybrid energy dissipation system (PHEDS) consists of rate dependent devices in series with rate independent devices, is installed in Steel moment resisting frame (SMRF) to improve energy dissipation capacity while any seismic event. Analytical development of model in SAP 2000 and performance based design of energy dissipating devices (EDD), were the basic objectives of the study. High damping rubber damper (HDRD) is a rate dependent device whereas elastic springs and buckling restrained braces (BRB) are rate independent devices. The analytical models confirmed the expected phased behavior and energy dissipation capabilities. An incremental dynamic analysis (IDA) was carried out to compare the effect of energy dissipating devices on overall seismic response of SMRF, a dual BRB-SMRF system, and a dual PHEDS-SMRF system. The results demonstrate that the PHEDS has potential as an energy dissipation system and improve the performance of the structure during a seismic event.
Mass distribution of multiple tuned mass dampers for vibration control of structures
International Journal of Civil and Structural Engineering, 2012
The mass distribution is one of the important parameter for MTMD (Multiple Tuned mass damper) for... more The mass distribution is one of the important parameter for MTMD (Multiple Tuned mass damper) for reducing effectively dynamic response of a main system. By controlling mass distribution along with other parameters like damping ratio, frequency range, number of dampers, response of the main system can be controlled. Different mass distributions like parabolic mass distribution and bell-shaped mass distribution are studied and its effect on controlling the dynamic response of the system is reported. To increase the effectiveness of the MTMD system, modified parabolic mass distribution and modified bell shaped mass distribution by skewing the mass distribution is proposed. Optimum parameters for MTMD with optimum mass distribution and main system damping varied as 2% and 5% are presented. Among the various mass distributions proposed in the present study Modified bell-shaped mass distribution for MTMD is superior. It was found to be more promising in terms of reducing dynamic response...
Multiple tuned liquid sloshing dampers for across-wind response control of benchmark tall building
Innovative Infrastructure Solutions, 2021
The miss-tuning of multiple tuned liquid sloshing dampers (MTLSDs) on wind-excited benchmark tall... more The miss-tuning of multiple tuned liquid sloshing dampers (MTLSDs) on wind-excited benchmark tall building is investigated in the present study. For the present study, 76 storied benchmark tall building is considered. Shallow water wave theory was used to model liquid sloshing in MTLSDs. The combined structure-MTLSDs system's governing equations of motion were expressed in the state-space variable, and the response was numerically calculated. A comparison was made between structural responses of uncontrolled building and building controlled with MTLSDs. Further, MTLSDs effectiveness is evaluated using a scalogram in the time–frequency domain. It was found that MTLSDs effectively reduce the building responses in a similar way like tuned liquid sloshing dampers (TLSDs). However, TLSDs are slightly more effective than MTLSDs for the same mass ratio. But, under miss-tuning conditions, the MTLSDs outperformed the TLSDs, and the structural response was found to be less than allowable limits recommended by the motion perception guidelines. It was found that MTLSDs are slightly better at controlling the higher mode response than TLSDs.
Bulletin of the New Zealand Society for Earthquake Engineering, 2006
Seismic response of multi-storied base-isolated building on various isolation systems connected u... more Seismic response of multi-storied base-isolated building on various isolation systems connected using viscous dampers to an adjacent dissimilar base-isolated or fixed-base building is investigated. The multi-storied buildings are modeled as a shear type structures with lateral degree-of-freedom at each floor, which are connected at different floor levels by the viscous dampers. Performance of this novel combination is studied by deriving the governing equations of motion and solving it in the incremental form using Newmark's step by-step method of integration. The variation of top floor absolute acceleration and bearing displacement under different real earthquake ground motions is computed to study the behavior and effectiveness of the connected systems. It is concluded that connecting the two adjacent base-isolated buildings with the viscous dampers is helpful in controlling large bearing displacement in the base-isolated structures; thereby, eliminating isolator damages arisi...
Semi-active friction dampers for seismic control of structures
Smart Structures and Systems, 2008
ABSTRACT Magnotorheological (MR) dampers have been demonstrated to be more effective in reducing ... more ABSTRACT Magnotorheological (MR) dampers have been demonstrated to be more effective in reducing the structural response due to earthquakes using only a small amount of external power. The performance of MR damper depends upon type of control law used and the damper force is directly depends on the input command voltage. The purpose of this study is to evaluate the effectiveness of input command voltage on MR damper system against recently proposed control laws under different earthquakes. The magnitude of control force increases with the increase in the input command voltage of MR damper, however for the different damper locations and configurations maximum command voltage to the current driver may not always effective in reducing the structural responses. To investigate the effective performance of the MR dampers, different control algorithms with multiple MR damper locations are considered in this study. A phenomenological model of a shear-mode MR damper, based on a Bouc–Wen element, is employed in the analysis of the controlled building. The control algorithms are tested on a five-story framed building and parametric study on variation in the input command voltage is conducted for different real earthquake ground motions. The numerically evaluated optimum parametric values are considered for the analysis of the different damper locations in the building in order to reduce the displacement, acceleration and the base shear of the building. It is shown numerically that the performance of the MR damper has a great potential in suppressing structural vibrations over a wide range of seismic inputs by selecting appropriate optimum input command voltages.
Seismic control of cable-stayed bridge using semi-active hybrid system
Bridge Structures, 2006
... md is the mass of the bridge deck and ob º2p/Tb is the isolation frequency of ... MR dampers ... more ... md is the mass of the bridge deck and ob º2p/Tb is the isolation frequency of ... MR dampers are relatively new semi-active control devices that use MR fluids to provide controllable dampers ...A typical MR fluid consists of 2040 percent by volume of relatively pure, 3 10 micron ...
Structure and Infrastructure Engineering, 2010
This paper investigates the effectiveness and limitations of seismic isolation for the earthquake... more This paper investigates the effectiveness and limitations of seismic isolation for the earthquake protection of a cablestayed bridge under bi-directional seismic actions. A simplified lumped mass finite element model of the Quincy Bayview Bridge at Illinois is developed for the investigation. The deck of the bridge is isolated from the towers by using elastomeric and sliding isolation systems. For the non-linear isolation systems, the interaction between the restoring forces in two orthogonal horizontal directions is duly considered in the response analysis. The seismic response of the bridge is obtained by solving the governing equations of motion in the incremental form using an iterative stepby-step method. A parametric study is also performed by varying important parameters of the isolation systems. The seismic response of the isolated cable-stayed bridge is compared with the corresponding response of the bridge without isolation systems. The results of the investigation indicate that the peak base shear response of the towers and deck accelerations are significantly reduced by the isolation. The displacement response of the hysteretic isolation systems is found to be increased when the bi-directional interaction of the bearing force is considered in the response analysis. Furthermore, it is also found that the response of the bridge is significantly affected by the variation in the parameters of the isolation systems.
Behaviour of liquid storage tanks with VCFPS under near-fault ground motions
Structure and Infrastructure Engineering, 2012
ABSTRACT Earthquake response of slender and broad liquid storage steel tanks isolated with variab... more ABSTRACT Earthquake response of slender and broad liquid storage steel tanks isolated with variable curvature friction pendulum systems (VCFPSs) is investigated under near-fault motions. The tanks isolated with VCFPS are idealised with three-degrees-of-freedom associated with convective, impulsive and rigid masses. The frictional forces mobilised at the interface of the VCFPS are assumed to be velocity independent. The governing equations of motion of isolated tank are derived and solved in the incremental form using Newmark's method. For comparative study, the seismic response of liquid storage tanks with the VCFPSs is compared with that of same liquid storage tanks isolated using the friction pendulum systems (FPSs). The seismic response of isolated liquid storage tanks is also compared with that of the non-isolated tanks. Further, a parametric study is carried out to critically examine the behaviour of liquid storage tanks isolated with the VCFPSs. The important parameters considered are the friction coefficient of VCFPS, the fundamental period at the centre of the sliding surface of VCFPS and the tank aspect ratio. It is observed that under near-fault ground motions, the VCFPS is quite effective in controlling the seismic response, viz. the base shear, the sloshing displacement and the impulsive displacement, of liquid storage tanks.
Structural Control and Health Monitoring, 2008
The seismic response of a flexible multi-storey building isolated with variable friction pendulum... more The seismic response of a flexible multi-storey building isolated with variable friction pendulum system (VFPS) is investigated under normal component of six near-fault ground motions. The VFPS, an advanced friction base isolator, is proposed in this study. The variation of the friction coefficient in VFPS is such that up to a certain value of displacement the frictional force increases and then it decreases with further increase in displacement. Such variation is selected with the criterion that the isolator displacement and building base shear decrease significantly without much alteration to superstructure acceleration under near-fault ground motions. The governing equations of motion of building isolated with VFPS are derived and solved in the incremental form by using Newmark's step-by-step method assuming linear variation of acceleration over small time interval. In order to verify the effectiveness of VFPS, the seismic responses are compared with that of the same building isolated by conventional friction pendulum system (FPS). A parametric study is also carried out to critically examine the behaviour of building isolated with VFPS. The important parameters considered are the number of stories of superstructure, initial time period and isolation period of the VFPS. In addition, the seismic response of building isolated with VFPS under simple cycloidal pulses is also investigated. From the above investigations, it was concluded that the VFPS is quite effective for controlling the seismic response of buildings under near-fault ground motions.
Variable dampers for earthquake protection of benchmark highway bridges
Smart Materials and Structures, 2009
ABSTRACT The dynamic behaviour of benchmark highway bridges using variable dampers under six bidi... more ABSTRACT The dynamic behaviour of benchmark highway bridges using variable dampers under six bidirectional earthquake ground motions is presented. A viscous damper is used as a passive control device and a variable damper, developed from an MR (magnetorheological) damper, is used as a semi-active control device. The study is based on the simplified lumped-mass finite-element model of the 91/5 highway bridge in Southern California. The prime aim of the study is to investigate the effectiveness of viscous dampers and variable dampers with a friction-type damping force scheme and a two-step viscous damping force scheme, with important parametric variation. Velocity-and displacement-dependent models of a variable damper are used. Numerical simulations are conducted by installing the devices between the deck and abutments of the bridge. The seismic response of the bridge is compared with the corresponding uncontrolled case, and controlled by alternative sample control strategies. The results of the investigation clearly indicate that the base shear and mid-span displacement are reduced substantially by these protective devices. It is concluded that variable dampers are quite effective in considerably reducing the large bearing displacements, thereby eliminating the isolator damages. The control effect of a viscous damper, and the two pre-set damping schemes of a variable damper in particular, is quite satisfactory in reducing the peak response quantities of the bridge to a level comparable to or better than that of the sample passive, semi-active and active controllers.
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Papers by Dr. R. S. Jangid