About
130
Publications
30,412
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
947
Citations
Introduction
Additional affiliations
April 1987 - October 2015
Publications
Publications (130)
Torsional forces may be induced in a building during dynamic excitation when the center of mass does not coincide with the center of rigidity. Estimating the modal parameters of a building structure with a lumped mass on each floor is a critical step in the design phase of a structure. The elastic dynamic response of a structure for any generalized...
A dual piezoelectric-based embedded transducer employing electromechanical impedance (EMI) technique is used for monitoring the curing of cement mortar. The transducer, comprising of two piezoelectric patches pasted on a metal plate, used with a miniature impedance analyzer having a simple peak-finding algorithm, results in an economical monitoring...
Monitoring the hardening of concrete during construction, is important to ensure proper strength gain and timely removal of formwork without compromising safety. Existing non-destructive testing (NDT) techniques mostly require sophisticated equipment and technical expertise, which makes it less applicable for field monitoring. Alternatively, lead z...
Structural damage detection using unmanned Structural Health Monitoring techniques is becoming the need of the day with the technologies available presently. Sensors made of Lead Zirconate Titanate materials, due to their simplicity and robustness, are increasingly used as an effective monitoring sensor in Structural Health Monitoring. Continuous m...
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. E...
Living beings are formed of advanced biological and mechanical systems which exist for millions of years. It is known that various animals and insects right from small ants to huge whales have different weight carrying capacities, which is generally expressed as a ratio of their own bodyweights i.e., Strength to Bodyweight Ratio (SBR). The puzzle i...
Structural stability of freestanding stacks of trays containing spent fuel bundles submerged in spent fuel water pool during earthquake is of greater concern for safe storing and handling for further reprocessing of spent fuels. In the spent fuel water pool, spent fuel bundles are stacked in 25–30 trays and kept on floor without base locators or gu...
This paper presents the experimental studies that are carried out to investigate the effect of temperature on the characteristics of MR damper. Active research has been carried out to study the effect of factors such as input current/voltage, frequency and amplitude of input excitation on the characteristics of the damper, but very limited research...
Control of structures against the earthquake forces had been a keen topic of interest in research for past decades. Isolator being one such system which works passively to decouple the structure from the earthquake forces has many disadvantages such as large displacements, poor adaptability to varying ground conditions. Recently, magnetorheological...
Open Ground Storey (OGS) in multistoried buildings is meant for a parking space within a building plan. These buildings have reduced stiffness at the ground storey due to absence of in-fill walls. The abrupt change in the stiffness of the open ground storey compared to the stories at the top result in huge seismic displacement demand, to be borne b...
Damage identification of the concrete pile element through torsional wave propagation technique is studied in this paper. Concrete pile foundations are often prevalent in all engineering structures and their safety is paramount for obviating the failure. Damage detection and estimation in a substructure is difficult because the visual image of the...
A damage evaluation methodology in a sagged prismatic rod through application of wave propagation mechanics is presented, and an experimental investigation illustrated for damage detection using lead zirconate titanate (PZT) piezoelectric transducers. Discontinuity in the form of variation of the cross-sectional area (impedance mismatch) is induced...
A three-storey half scale Reinforced Concrete (RC) building frame model, fitted with yielding type X-shaped metallic elasto-plastic damper at the ground floor level, is designed and fabricated to study its seismic response characteristics. Experimental studies are carried out using the 4m × 4m tri-axial shake-table facility to evaluate the seismic...
Information regarding the early strength gain of fresh concrete determines the time for the removal of form work and the transfer of pre-stressing forces for pre-stressed concrete. An ultrasonic based non-destructive evaluation of early strength gain may not work for concrete in fluid and semi-solid phases. A possible alternative is a lead zirconat...
This paper presents the results of a computational and experimental validation exercise performed towards damage identification of a sagged rod with known damage by using the coupled axial–flexural wave interaction mechanics. Towards simulating the damage scenario in a sagged conductor made of steel wire rope, a prismatic steel rod is taken up for...
The knowledge of strength gain of reinforced concrete structures facilitates speedy and accurate decision in formwork removal and transfer of pre-stressing forces for pre-stressed concrete. In the current study, a set of two smart aggregates embedded in concrete cubes have been investigated for their suitability in evaluating the strength gain duri...
Majority of housing tenements in developing countries constitute a class of structures termed as ‘open ground storey (OGS) structures’ of medium rise and which are highly vulnerable to strong seismic motions. Evaluation of displacement demand magnifier (DDM) for quantifying the vulnerability of OGS structures and variation of DDM with reference to...
Many devastating earthquakes exceeding the design basis levels have occurred in the past. Safety assessment of equipments and piping systems of industrial/nuclear safety related structures subjected to earthquakes beyond design basis levels necessitates consideration of the structural nonlinearity. The In-structure or floor response spectra (FRS) a...
Changes in admittance signatures measured using Electro-Mechanical Impedance (EMI) technique with a lead zirconate titanate (PZT) transducer, embedded in concrete is an indirect estimate of the localized changes in dynamic stiffness of the concrete in the proximity of the sensor. Experiments and observations on the EMI signatures obtained from PZT...
Knowledge about the strength gain of reinforced concrete structures facilitates speedy and accurate decision making in formwork removal and transfer of prestressing forces for prestressed concrete. In the current study, a set of two smart aggregates embedded in concrete cubes have been investigated for their suitability in evaluating the strength g...
The northeastern part of India which includes the seven sister states and Sikkim, is very prone to seismic activities. Over the years, a number of earthquakes have caused large disturbances to public life and property in this region. The population in this region mainly consists of indigenous tribes, who inhabit the forests and rural areas. Hence t...
This paper investigates the damage identification of the concrete pile element through axial wave propagation technique using computational and experimental studies. Now-a-days, concrete pile foundations are often common in all engineering structures and their safety is significant for preventing the failure. Damage detection and estimation in a su...
Damage identification of the concrete pile element through torsional wave propagation technique is studied
in this paper. Concrete pile foundations are often prevalent in all engineering structures and their safety
is paramount for obviating the failure. Damage detection and estimation in a sub-structure is difficult
because the visual image of the...
Structural stability of freestanding stacks of trays containing spent fuel bundles submerged in spent fuel water pool during earthquake is of greater concern for safe storing and handling for further reprocessing of spent fuels. In the spent fuel water pool, spent fuel bundles are stacked in 25-30 trays and kept on floor without base locators or gu...
Time series analysis is being used popularly in structural health monitoring mainly because of its output-only and non-modal approach. Generally, the damage features are extracted either from the coefficients or the prediction errors of the time series models. However, when the incipient damage is small like minor cracks, the damage features of pop...
Magnetorheological (MR) dampers are devices that can be used for structural vibration reduction under seismic excitation. These devices are used in semi-active control which require less power compared to active devices and offer high reliability compared to passive devices. Despite the advantages of MR damper, use of these dampers in an effective...
In the field of the geotechnical engineering, wave propagation based tools have found increasing application in the area of Structural Health Monitoring (SHM). Damage detection and estimation in a sub-structure is challenging as the visual picture of the sub-structure is never known and the state of the structure or foundation can be inferred only...
Seismic performance evaluation of shear wall is essential as it is the major lateral load resisting member of a structure. The ultimate load and ultimate drift of the shear wall are the two most important parameters which need to be assessed experimentally and verified analytically. This paper comprises the results of monotonic tests, quasi-static...
Shake table testing is a viable validation tool for bench-marking the analytically computed seismic response of under-water structural models with fluid–structure interaction effects. Conventional displacement sensors like LVDTs (linearly variable differential transformer) cannot be used for under-water response measurements as they require a stati...
Open ground storey is a typical feature in the modern multi storey constructions in urban India. These buildings are normally not designed as per the earthquake resistant design proposed in the BIS codes. In order to control the vibration response of high rise buildings during seismic events, passive damping devices are most commonly used for energ...
The paper presents an application of wave propagation
for damage detection
in an aluminum plate. The experimental investigation was conducted on an aluminum plate by generating the wave with Lead Zirconate Titanate (PZT) patches by function generator. Normal responses are measured with the Scanning Laser Doppler Vibrometer
(SLDV). Eleven sine cycle...
This paper describes the ductility behavior of Laced Reinforced Geopolymer concrete beam (LRGPC). Laced Reinforced Concrete (LRC) construction techniques are widely used in blast resistant design and seismic resistant design of structures. LRC structural element consists of equal reinforcement in tension and compression faces along with lacings. La...
This paper presents a critical review of literature on Structural Health Monitoring (SHM) of Overhead Transmission Line (OVTL) conductors. Different health monitoring techniques such as wave propagation mechanics and other significant methodologies used for remaining life prediction is discussed in detail. From the critical review of monitoring tec...
The paper presents an explicit damage visualization methodology in an aluminum plate through the application of wave propagation mechanics. The present work describes a series of experiments and a special signal processing technique, for speedy spatial visualization of damage in different sets of test specimens. Experiments on three aluminum specim...
The form work removal at suitable time plays an important role in strength gain for reinforced concrete
structures and transfer of pre-stressing forces for pre-stressed concrete. In the present study, smart
aggregates embedded in concrete cubes have been examined for their suitability in estimating the
Electro-Mechanical Impedance (EMI) signatures...
Identification and estimation of damage in a sub-structure is challenging as the visual picture of the sub-structure is never known and the state of the structure or foundation can be inferred only through its static and dynamic response. The paper presents the results of a computational modeling of the wave propagation process through a prismatic...
Information regarding the early strength gain of fresh concrete determines the time for the removal of form work and the transfer of pre-stressing forces for pre-stressed concrete. An ultrasonic based non-destructive evaluation of early strength gain may not work for concrete in fluid and semi-solid phases. A possible alternative is a lead zirconat...
Identification and estimation of damage in a sub-structure is challenging as the visual picture of the sub-structure is never known and the state of the structure or foundation can be inferred only through its static and dynamic response. The paper presents the results of a computational modeling of the wave propagation process through a prismatic...
W
ave propagation based automatic structural health monitoring techniques and the warning-alert systems are widely adopted in aerospace and nuclear industry. These techniques are however, not in a matured state of development for civil structures and are evolving. Hence research in this area is of paramount importance. This paper deals with axial w...
Wave propagation based automatic structural health monitoring techniques and the warning-alert systems are widely adopted in aerospace and nuclear industry. These techniques are however, not in a matured state of development for civil structures and are evolving. Hence research in this area is of paramount importance. This paper deals with axial wa...
Wave propagation based automatic structural health monitoring techniques and the warning-alert systems are widely adopted in aerospace and nuclear industry. These techniques are however, not in a matured state of development for civil structures and are evolving. Hence research in this area is of paramount importance. This paper deals with axial wa...
Ductile behaviour of shear wall is a prominent issue as the shear wall is a specially designed structural wall to resist earthquake forces. Ductility of shear wall is influenced by several factors like aspect ratio, axial load on shear wall, percentage of vertical reinforcement and percentage reinforcement in boundary element. A parametric study is...
Accounting for the increasing importance of the buried pipeline systems in India, the serviceability of pipeline need to be maintained in the event of a natural calamity. An analytical study to manifest the mechanical behavior of buried gas steel pipelines subjected to strike-slip fault has been addressed. A solution algorithm for an existing analy...
It is essential to have a robust sensor fault detection and isolation algorithm integrated with successful online continuous structural health monitoring scheme to avoid false alarms. In this work, a sensor fault detection and isolation technique based on null subspace method is presented. The robustness of the proposed sensor failure detection and...
Response control of structures subjected to seismic excitations has been a potential area of research in the field of earthquake engineering. Base isolation is one such powerful technique in passive response control of structures. The base isolation system decouples the structure from the horizontal components of the ground motion by imposing flexi...
Wave propagation based automatic structural health monitoring techniques and the warning alert systems are widely adopted in aerospace and nuclear industry. These techniques are however, not in a matured state of development for civil structures and are evolving. Hence research in this area is of paramount importance. This paper deals with axial wa...
The paper presents an application of wave propagation for damage detection in an aluminum plate. The experimental investigation was conducted on an aluminum plate by generating the wave with Lead Zirconate Titanate (PZT) patches by function generator. Normal responses are measured with the Scanning Laser Doppler Vibrometer (SLDV). Eleven sine cycle...
Structures designed according to performance-based seismic design (PBSD) are required to satisfy the target performance. PBSD requires extensive research for capacity evaluation and development of reliable nonlinear models. Shear walls are the ideal choice to resist lateral loads in multistoried RC buildings. They provide large strength and stiffne...
Details of the investigations on the application of Electro Mechanical Impedance (EMI) technique using smart piezoelectric (PZT) sensors for damage detection of structures are presented in this paper. The behavior and the ability of this method to detect damages, in a homogenous material are studied for its effective utilization in structural healt...
The response of a multi supported structure subjected to spatially varying ground motion at its different supports is of great importance for structures like bridges, pipe lines, viaducts, tunnels etc,. Various reasons like local site conditions, wave passage effect, incoherence effect and attenuation effect tend to induce a phase difference and ti...
Details of the investigations on the application of Electro Mechanical Impedance (EMI) technique using smart piezoelectric (PZT) sensors for damage detection of structures are presented in this paper. The behavior and the ability of this method to detect damages, in a homogenous material are studied for its effective utilization in structural healt...
Details of the investigations on an unexplored application of Electro Mechanical Impedance (EMI) technique using smart piezoelectric (PZT) sensors for damage detection of concrete shear wall structures under crack opening and closing is presented in this paper. The behavior and the ability of this method to detect damages, in a heterogeneous quasi-...
Active control of civil and aerospace structures is an inter-disciplinary science, which elicits inputs from structural engineers, electronics and electrical engineers. The algorithms developed are mathematically and computationally intensive, and are required to be operational in real-time conditions and require validation from experimental demons...
The multiple base motion effect on hydrodynamic pressure, acceleration of tank and fluid surface elevation problem in Elevated water tank is understood as a Fluid-Structure-Soil Interaction problem. Where, Soil-Structure interaction causes rocking motion and Fluid Structure interaction causes the hydrodynamic behaviour of water tank. According to t...
The supplemental passive and semi-active dampers such as viscousfluid dampers, magnetorheological (MR) dampers are increasingly used to provide enhanced seismic protection of structures. A three-storey quarter length scale steel moment resisting frame (SMRF) model,fitted with two scissor-jack-MR damper systems placed at groundfloor level, is design...
http://www.lib.ncsu.edu/resolver/1840.20/30959
Shake table testing is a viable validation tool for bench-marking the analytically computed seismic response of under-water structural models with fluid–structure interaction effects. Conventional displacement sensors like LVDTs (linearly variable differential transformer) cannot be used for under-water response measurements as they require a stati...
SUMMARY Structural health monitoring of existing infrastructure is currently an active field of research, where elaborate experimental programs and advanced analytical methods are used in identifying the current state of health of critical structures. Change of static deflection as the indicator of damage is the simplest tool in a structural health...
Keywords:
seismic performance;magnetorheological dampers;toggle braces mechanism;dynamic characteristics;steel moment-resistant frame
SUMMARY
The supplemental passive and semi-active dampers such as viscous fluid dampers and magnetorheological (MR) dampers normally placed in either Chevron or Toggle brace are increasingly used to provide enhanced...
Development of new technologies for seismic protection will better support the sustainable urban systems. The paper focuses on development of an innovative technology for seismic protection of bridges using smart materials. The seismic protection of structures with the use of special devices is widely accepted as a very effective technique, both fo...
Machine foundations are dynamically loaded structures whose response depends on a number of parameters such as strength, stiffness, mass, damping, soil-structure interaction and fatigue. Performance-based designs and evaluation procedures are gaining popularity particularly with respect to structures that have been built using codal provisions exis...
A four-stage procedure for effective management and maintenance scheduling for infrastructural facilities is presented. The structure/component needing immediate attention is identified during the first stage. The second stage investigations reveal local or global damage and also the location of damage, based on the principles of damage assessment....
Considerable research has been carried out in the recent years in the development of models to simulate the inelastic responses of reinforced concrete elements. The enhancement of ductility and the post-peak behaviour are of special interest for the seismic design of structures. Polymer modified fibre concretes are found to be ideal for seismic app...
Performance based design is an emerging area in earthquake engineering in which damage modeling of structural components plays an important role in achieving the performance objectives. Past researches in damage index evaluation indicated no obvious shear dependent trends on cyclic combined shear and flexure. Paper focuses in finding a simple and r...
Steady state vibration response of a machinery-supporting structure is strongly influenced by resonances closer to its operating speed. The coasting up/down response of the machinery and the corresponding signal may throw light on the proximity of resonances and pre-cautions can be taken to de-tune it away from the operating frequency. The paper pr...
The paper proposes a first stage structural health monitoring methodology using natural frequencies and static deflections as damage indicators. The idea is that the first stage monitoring can be done for a large number of bridges and vulnerable structures in a remote manner and the features extracted from the data should help in determining whethe...
The paper proposes two methodologies for damage identification from measured natural frequencies of a contiguously damaged reinforced concrete beam, idealised with distributed damage model. The first method identifies damage from Iso-Eigen-Value-Change contours, plotted between pairs of different frequencies. The performance of the method is checke...
The paper presents the results of a computational modeling for damage identification process for an axial rod representing an end-bearing pile foundation with known damage and a simply supported beam representing a bridge girder. The paper proposes a methodology for damage identification from measured natural frequencies of a contiguously damaged r...
Nickel titanium (NiTi) alloys are well known for their super elastic and shape memory properties and they belong to the class of shape memory alloys (SMA). Ability to sustain and recover large amounts of inelastic deformation during reversed cyclic loading with extra ordinary fatigue resistance make super elastic NiTi a suitable candidate for seism...
Development of new technologies for seismic protection will better support the sustainable urban systems. The paper aims in bringing out the efficacy of a Shape Memory Alloy (SMA) device in seismic protection of simply supported short span bridges for strong ground motions. The damper cum restraining device with re-centering capabilities, developed...
This paper highlights the importance of selection of a suitable ductile composite, incorporating it into the predefined locations, for better seismic performance. Replacement of normal concrete with ductile composites at plastic hinge locations is an idea, which can be well thought for in the conceptual approach to structural design. A simple exper...
Safety and Performance requirements of building structures have necessitated the development of High Performance Concretes in the recent years. Polymer Modified Fiber Concrete (PMFC) assumes an important place in this regard. Ductility of reinforced concrete elements can be taken advantage of for design of structures against seismic loading. Polyme...
The paper deals with the applications of spectral finite element method to the dynamic analysis of framed foundations supporting high speed machines. Comparative performance of approximate dynamic stiffness methods formulated using static stiffness and lumped or consistent or average mass matrices with the exact spectral finite element for a three...