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Amlan K. Sengupta

Other affiliations: Indian Institutes of Technology
Bio: Amlan K. Sengupta is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topic(s): Precast concrete & Girder. The author has an hindex of 5, co-authored 20 publication(s) receiving 79 citation(s). Previous affiliations of Amlan K. Sengupta include Indian Institutes of Technology.

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01 Jun 2009-
Abstract: To prevent disaster in future earthquakes, the existing deficient buildings need to be retrofitted. One way of retrofitting the columns in reinforced concrete multistoreyed buildings is concrete jacketing. The present study has investigated the effect of jacketing on the flexural strength and performance of columns. First, slant shear tests were conducted to study the interface between the old and new concrete. Second, column specimens were tested to study the strength. Third, beam-column-joint sub-assemblage specimens were tested to study the ductility (or energy absorption) and energy dissipation. Analytical investigations were carried out to predict the experimental results. A lamellar approach and a simplified method of analysis were used for the prediction of the axial load versus moment interaction curves and moment versus curvature curves for the retrofitted columns. An incremental nonlinear analysis was adopted to predict the lateral load versus displacement behaviour for a retrofitted sub-assemblage specimen. Guidelines for the retrofitting of columns by concrete jacketing are provided.

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13 citations




Journal ArticleDOI
Abstract: The rate of corrosion of the reinforcing bars is one of the important parameters required to estimate the residual service-life of a reinforced concrete (RC) bridge deck. In the present study, first, the linear polarization resistance technique was used to measure the corrosion rates of plain mild steel and cold twisted deformed (CTD) bar specimens, which were typically used in the older existing bridges. To consider the variability of a corrosion rate, the frequency distributions of the corrosion rates for the two types of bars were determined. Next, a probabilistic approach was adopted for assessing an existing RC girder-and-slab road bridge deck, subjected to corrosion of bars attributable to air-borne chlorides. A computational model was developed using the Monte Carlo simulation method, to assess the reduction in the flexural capacity of a typical girder. It was observed that the reduction in the mean capacity and the dispersion of the capacity with respect to time, were high with the measure...

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7 citations


Journal ArticleDOI
A. Adukadukam1, Amlan K. Sengupta2Institutions (2)
Abstract: In the seismic analysis of a framed building with masonry infill walls, it is necessary to model the effect of the walls on the lateral stiffness, strength and ductility of the building. The equivalent strut method is convenient for modelling the walls in a large building. However, an appropriate axial load versus deformation relationship for the strut is required in a nonlinear static method of seismic analysis, such as the pushover analysis. The present study proposes a nonlinear axial hinge property for the strut, with suitable performance levels. First, the equivalent strut method and the suitability of two approaches available in the literature for modelling the properties of the struts, are briefly discussed. Next, the nonlinear axial load versus deformation relationship is developed based on experimental data compiled from the literature. The parabolic–plastic relationship is idealized as a tri-linear axial hinge property, so that it can be incorporated in commercial software for undertaking pushover analysis. Next, the use of the hinge property is demonstrated in the pushover analyses of two framed reinforced concrete buildings. The pushover curves based on the proposed hinge property shows improved modelling of the inelastic drifts of the buildings. Although the modelling of a wall using a single strut has limitations, the proposed methodology is practical for a pushover analysis of a building.

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6 citations


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Dissertation
26 May 2012-
Abstract: Presence of infill walls in the frames alters the behaviour of the building under lateral loads. However, it is common industry practice to ignore the stiffness of infill wall for analysis of framed building. Engineers believe that analysis without considering infill stiffness leads to a conservative design. But this may not be always true, especially for vertically irregular buildings with discontinuous infill walls. Hence, the modelling of infill walls in the seismic analysis of framed buildings is imperative. Indian Standard IS 1893: 2002 allows analysis of open ground storey buildings without considering infill stiffness but with a multiplication factor 2.5 in compensation for the stiffness discontinuity. As per the code the columns and beams of the open ground storey are to be designed for 2.5 times the storey shears and moments calculated under seismic loads of bare frames (i.e., without considering the infill stiffness). However, as experienced by the engineers at design offices, the multiplication factor of 2.5 is not realistic for low rise buildings. This calls for an assessment and review of the code recommended multiplication factor for low rise open ground storey buildings. Therefore, the objective of this thesis is defined as to check the applicability of the multiplication factor of 2.5 and to study the effect of infill strength and stiffness in the seismic analysis of low rise open ground storey building. Infill walls can be modelled in commercial software using two-dimensional area element with appropriate material properties for linear elastic analysis. But this type of modelling may not work for non-linear analysis since the non-linear material properties for a two-dimensional orthotropic element is not very well understood. Seismic evaluation of an existing reinforced concrete (RC) framed building would invariably require a non-linear analysis. Published literature in this area recommends a linear diagonal strut approach to model infill wall for both linear (Equivalent Static Analysis and Response Spectrum Analysis) and nonlinear analyses (Pushover Analysis and Time History Analysis). An existing RC framed building (G+3) with open ground storey located in Seismic Zone-V is considered for this study. This building is analyzed for two different cases: (a) considering both infill mass and infill stiffness and (b) considering infill mass but without considering infill stiffness. Two separate models were generated using commercial software SAP2000. Infill weights were modelled through applying static dead load and corresponding masses considered from this dead load for dynamic analyses. Infill stiffness was modelled using a diagonal strut approach. Two different support conditions, namely fixed end support condition and pinned end support condition, are considered to check the effect of support conditions in the multiplication factors. Linear and non-linear analyses were carried out for the models and the results were compared. The analysis results show that a factor of 2.5 is too high to be multiplied to the beam and column forces of the ground storey of low-rise open ground storey buildings. This study conclude that the problem of open ground storey buildings cannot be identified properly through elastic analysis as the stiffness of open ground storey building and a similar bare-frame building are almost same. Nonlinear analysis reveals that open ground storey building fails through a ground storey mechanism at a comparatively low base shear and displacement and the mode of failure is found to be brittle. Linear and nonlinear analyses show that support condition influences the response considerably and can be an important parameter to decide the force amplification factor.

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11 citations



Journal ArticleDOI
Abstract: Several simplified and advanced methods have been proposed to evaluate the behavior of masonrywalls under in-plane loads, but their implementation in standard commercial software remains still an exception. In this paper, a novel 1D approach called Multi-Pier MP method, which has the advantage that can be used in a commercial software and requires only truss elements with a non-linear softening behavior, is presented. In the model, a masonry structure in-plane loaded is transformed in an assemblage of piers (vertical trusses) and diagonal connecting elements (braces), ensuring by elastic stiffness equivalence that a masonry representative element of volume behaves in the same manner as the 1D system constituted by two vertical trusses and two diagonal braces. After a validation at a unit cell level, where geometric and mechanical properties of the trusses are set in order to reproduce correctly masonry behavior respectively under axial loads, combined shear and compression stresses and bending and shear actions, four masonry full scale shear walls with different length to width ratios and presence or absence of openings are analyzed in the non-linear static range. In addition to experimental results, two Heterogeneous Discrete Element and Finite Element Methods were used with validation purposes. Excellent match among MP Method results, experimental evidences and alternative advanced numerical heterogeneous approaches is found, as far as the prediction of ultimate load, post peak behavior, initial stiffness and failure mechanisms is concerned. The model is also capable to follow at each step of loading the spreading and position of tensile and shear cracks.

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8 citations


Journal ArticleDOI
Ahed Habib1, Umut Yildirim1, Özgür Eren1Institutions (1)
Abstract: Seismic retrofitting and/or the strengthening of RC columns has been a popular area of research for decades. Currently, reinforced concrete jacketing is considered as the most common technique for repairing and strengthening of deficient and/or damaged RC columns. In general, this technique is a practical solution to recover and improve the load-carrying capacity and stiffness of reinforced concrete columns in earthquake-prone countries. It is a simple method that can be applied to any column cross section for rehabilitating structural elements by encasing the old member in a stiff jacket. The importance of this approach comes from its ability to improve the load-carrying capacity, strength, and stiffness of any column section significantly without the need for experienced labor or complicated installations process. This paper summarizes and compares general conclusions of recent investigations on columns retrofitting using reinforced concrete jacketing. As a part of this study, experimental, analytical, and numerical studies were reviewed and their findings were collected and discussed.

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7 citations


Journal ArticleDOI
06 Jan 2021-
Abstract: Perforations adversely affect the structural response of unreinforced masonry walls (UMW) by reducing the wall’s load bearing capacity, which can cause serious structural damage. In the absence of a reliable procedure to accurately predict the load bearing capacity and stiffness of perforated masonry walls subjected to in-plane loadings, this study presents a novel approach to measure these parameters by developing simple but practical equations. In this regard, the Multi-Pier (MP) method as a numerical approach was employed along with the application of an Artificial Neural Network (ANN). The simulated responses of centrally perforated UMW by the MP method were validated utilizing full-scale experimental walls. The validated MP model was used to generate a simulated database. The simulated database includes results of analyses for 49 different configurations of perforated masonry walls and their corresponding solid masonry walls. The effect of the area and shape of the perforations on the UMW’s behavior was evaluated by the MP method. Following the outcomes of the verified MP method, the ANN is trained to develop empirical equations to accurately predict the reduction in the load bearing capacity and initial stiffness due to the perforation of UMW. The results of this study indicate that the perforations have a significant effect on the structural capacity of the UMW subjected to in-plane loadings.

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7 citations


Network Information
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Performance
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Author's H-index: 5

No. of papers from the Author in previous years
YearPapers
20202
20196
20153
20141
20132
20121

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Author's top 5 most impactful journals

The Indian Concrete Journal

2 papers, 12 citations

Structures

2 papers, 7 citations

Structural Concrete

1 papers, 9 citations

Engineering Failure Analysis

1 papers, 1 citations