Department of Civil Engineering

Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

This article presents the design of a tuned mass damper with a conical spring to enable tuning to the natural frequency of the system at multiple values, as may be convenient in case of a system with fluctuations in the mass. The principle and design procedure of the conical spring in the context of a varying mass system are presented. A passive feedback control mechanism based on a simple pulley-mass system is devised to cater to the multi-tuning requirements. A design example of an elevated water tank with fluctuating water content, subjected to ground excitation, is considered to numerically illustrate the efficiency of such a tuned mass damper associated with the conical spring. The conical spring is designed based on the tuning requirements at different mass conditions of the elevated water tank by satisfying the allowable load bearing capacity of the spring. Comparisons are made with the conventional passive tuned mass damper with a linear spring tuned to the full tank condition. Results from time history analysis reveal that the conical spring-tuned mass damper can be successfully designed to remain tuned and thereby achieve significant response reductions under stiffening conditions of the primary structure, whereas the linear spring-tuned mass damper suffers performance degradation because of detuning, whenever there is any fluctuation in the system mass. © The Author(s) 2021.

World University root node

JVC/Journal of Vibration and Control

A novel tuned mass-conical spring system for passive vibration control of a variable mass structure

Purpose: Critics of claims about building information modeling’s (BIM’s) capability to revolutionize construction industry practices describe it as overhyped, fallacious and therefore suggest that there is need for a more critical examination of its change impacts. Others have posited that the changes BIM induces are evolutionary rather than revolutionary. In this vein, the purpose of this paper was to undertake a careful analysis of the nature of such changes to distil actual changes that happened, and the type of agency that brings such changes about. Design/methodology/approach: Drawing from appropriate qualitative research strategies, data was collected through key informant interviews from consulting organizations in South Africa that have implemented BIM within their organizations and on projects. Findings: Changes in organizations’ work practices were evident in their workflows, formal/informal methods of interaction, norms, leadership and authority structures, remuneration and the way work was conceived or conceptualized. Furthermore, changes in organizational work practices do not solely occur through the direct agency of the BIM tool’s implementation. Instead, BIM-induced change occurs by delegated, conditional and needs-based agency – which are not mutually exclusive. Originality/value: The nature of changes in professional work practices could be misconstrued as being solely because of the actions of agents who actively participate in implementing BIM. The discussion in the literature has, therefore, been advanced from general to specific theoretical understandings of BIM-induced change, which emphasize the need for construction stakeholders to actively participate in developing the innovations that drive change in the industry rather than hand the power to drive change to BIM authoring and management application developers who have less stake in the industry. © 2021, Emerald Publishing Limited.

Fulltext

Construction Innovation

Distilling agency in BIM-induced change in work practices

Back-to-back mechanically stabilized earth (MSE) walls are being widely utilized as bridge abutments and highway ramps, considering their cost effectiveness and ease of construction. Though high quality well-graded granular fill is the most appropriate backfill material, owing to its scarcity, locally available low-quality soils are often used as backfill. Nevertheless, numerous failure cases of such walls with low-quality soil are reported, especially subsequent to the rainwater infiltration. The stiffness of reinforcement is a key parameter affecting the overall behaviour of MSE walls. The present study investigates the influence of reinforcement stiffness on the response of select fill, marginal fill, and hybrid-fill back-to-back MSE walls using a finite element (FE) based approach. Results show that stiffness of reinforcement has a significant effect on the overall performance of marginal fill wall upon rainfall infiltration. Specifically, with the increase of reinforcement stiffness, the infiltration induced facing displacement decreases and reinforcement tension increases. However, the performance of select fill and hybrid-fill walls following rainfall infiltration was found to be satisfactory even with low stiffness reinforcements and further improvement with increase of reinforcement stiffness was insignificant. The reduction of safety factors during infiltration was shown to be independent of reinforcement stiffness for all wall types. © 2021 Thomas Telford Ltd.

Geosynthetics International

Effect of Reinforcement Stiffness on the Response of Back-to-Back MSE Wall upon Infiltration

Distributed hydrological models account for spatial heterogeneity by discretizing the watershed into unique units based on the watershed characteristics. However, parameter estimation is one of the major tasks in the application of distributed hydrological models. The existing calibration methods for distributed hydrological models do not consider the spatial variability of the parameters across the basin, and, therefore, do not guarantee good simulations on locations other than the calibration outlets. This study proposes a calibration approach which preserves the heterogeneity of the parameters across the basin. The basic simulation units of the distributed models are grouped in this approach based on the land use and soil type, and a random perturbation of the parameters is performed in these groups during calibration. The proposed method is demonstrated through a case study of two watersheds in the USA using soil and water assessment tool (SWAT) model. The results indicate that the calibrated model simulations in the upstream gauged locations (other than that used for calibration) are much better in the proposed approach, in contrast to the currently employed calibration method. Nonetheless, it is also observed that the proposed calibration approach would be more effective in watersheds that have higher spatial heterogeneity. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.

Environmental Earth Sciences

Calibration of distributed hydrological models considering the heterogeneity of the parameters across the basin: a case study of SWAT model

Study region: Lower Apalachicola-Chattahoochee-Flint (ACF) River Basin, southeastern United States (U.S.). Study focus: Excessive groundwater withdrawal for irrigation from the Upper Floridan Aquifer is an important issue in the lower ACF River Basin as it has led to decline in groundwater levels as well as reduction in baseflows. Since the withdrawal is projected to further increase in the future, this study evaluated the impacts of the projected increase in irrigation on the groundwater levels as well as the stream-aquifer flux in the region. The study also identified regions that are most important for groundwater recharge. New hydrological insights into the region: Evaluation of the geohydrologic zones identified Upland Instream Karst as the most sensitive zone for recharge into the aquifer while zones in the region where the aquifer thickness was comparatively lower and close to the land surface was generally identified as sensitive. Simulation of the projected irrigation scenario predicted a reduction in groundwater levels by as much as 2.38 m, while a general reduction was predicted in much of the model domain. Large groundwater level reductions were mostly predicted in regions where the aquifer is comparatively thinner. Evaluation of the changes in stream-aquifer flux showed that flux reduced by as much as 33 % with large reductions predicted in the Lower Flint and Kinchafoonee watersheds. This study also helped identify localized zones and stream sections most susceptible to the impacts of increase in irrigation. © 2021 The Author(s)

Journal of Hydrology: Regional Studies

Assessment of impact in groundwater levels and stream-aquifer interaction due to increased groundwater withdrawal in the lower Apalachicola-Chattahoochee-Flint (ACF) River Basin using MODFLOW

The frequency of rainfall-triggered landslides is increasing across the world. Infiltration of rainwater into the slopes with low permeable soil increases the pore water pressure and reduces the stability of slopes. Also, in the recent past, Kerala experienced many rainfall-triggered landslides. One of the most efficient way to prevent rainfall-triggered landslides would be the usage of composite geosynthetics which can combine the functions of pore pressure dissipation and reinforcements. In the present study, soil is collected from a nearby site where landslide has occurred and the geotechnical characterisation of the soil was carried out. An attempt was made to investigate the performance of steep soil slopes with and without the geosynthetics when subjected to rainfall, numerically. The study highlights the importance of the use of a composite geogrid in reinforced soil slopes composed of locally available marginal soil. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Lecture Notes in Civil Engineering

Performance of Geosynthetic Reinforced Steep Soil Slopes at the Onset of Rainfall Infiltration

The current paper presents a perturbation-based stochastic eigenvalue buckling analysis of thin plates using element free Galerkin method. Spatial variation in Young's modulus is modeled as a homogeneous random field and moving least square-based shape function method is employed for discretizing the random field. Perturbation method is used to evaluate the statistics of buckling loads. Numerical examples wherein rectangular plates with different boundary conditions are solved and the statistics obtained are compared with those calculated using Monte Carlo simulation. Different parametric studies are also conducted. The results obtained from perturbation method are found to be reasonably accurate for coefficient of variation (CV) values less than 20% for random fields with normal distribution. Further it is observed that for random fields with lognormal distribution, the proposed method produces reasonably accurate results up to a CV of 30%. © 2021 World Scientific Publishing Company.

International Journal of Computational Methods

Perturbation-Based Stochastic Meshless Method for Buckling Analysis of Plates

In this study, element-free Galerkin method (EFGM), a meshless method, is proposed for wrinkling analysis of pre-stressed rectangular membranes. The mathematical model for studying wrinkling of pre-stressed membranes is derived by considering the bending stiffness, though it is negligible. Moving least-square approximation for deflection is constructed by considering three degrees of freedom per node. Essential boundary conditions are imposed using scaled transformation matrix method. Initially, compression-induced buckling of a homogeneous thin plate without pre-stress is solved to validate the method and then a pre-stressed homogeneous membrane is analyzed for both compression-induced and shear-induced wrinkling. Capabilities of the proposed method for membrane analysis are compared with that of the finite element method (FEM). Comparative study on wrinkling analysis using EFGM and different FEM element types in a commercial FEM package shows that in lower modes both methods show satisfying consistency in eigenvalues with respect to the total of number of nodes, while at higher modes EFGM shows better consistency than FEM. Further, the study is extended to wrinkling of nonhomogeneous membranes subjected to linearly-varying in-plane load. The results obtained from EFGM analysis is compared and found to be matching well with those available in the literature. © 2021 World Scientific Publishing Company.

Wrinkling Analysis of Pre-Stressed Rectangular Membranes Using Element-Free Galerkin Method

Agro-waste ashes can be used as supplementary cementitious materials in concrete. Although many studies have been reported on the use of rice husk ash as a pozzolan, only limited studies are attempted on the use of rice-straw ash in concrete. The composition of rice straw and the influence of thermochemical processing on the amorphous nature and microstructure of rice-straw ash are reported in this study. Moreover, compressive strength, water penetration test and rapid chloride permeability tests were conducted for rice-straw ash blended concrete. Results from the study indicate that rice-straw ash obtained from pyrolysis temperatures up to 700°C were amorphous and contained reactive silica. From considerations of strength, workability and durability, 10% rice-straw ash is observed to be the optimum level of replacement. Rice-straw ash blended concrete with 20% replacement level exhibited better performance against water penetration and chloride ingress than control concrete. © 2021 American Society of Civil Engineers.

Journal of Materials in Civil Engineering

Rice-Straw Ash as a Potential Supplementary Cementitious Material: Influence of Thermochemical Conversion on Its Properties

Study Region: The contiguous United States (CONUS). Study Focus: This study assesses the effects of the large-scale oceanic-atmospheric oscillations such as El Niño southern oscillation (ENSO), Atlantic Multidecadal Oscillation (AMO), North Atlantic Oscillation (NAO), and Pacific Decadal Oscillation (PDO) on streamflow levels. Two robust and powerful non-parametric procedures, namely, the Joint Rank Fit (JRFit) and the rank-based partial least squares regression are used to identify and quantify the strength and direction of teleconnections (individual analysis). Further, JRFit is used to model the interactive effects (coupled analysis) of ENSO with AMO/PDO/NAO cycles on streamflows. New Hydrological Insights for the Region: Individual analysis results identified new significant ENSO, PDO, AMO and NAO tele-connections with streamflows across CONUS. PLS analysis showed a stronger AMO teleconnection with streamflows compared to other oscillations. The coupled analyses results were categorized into three groups based on the types of interactions of the ENSO phases. Type 1 interactions where a phase of ENSO is modulated by phases of decadal/multidecadal cycles, are seen across all (majority of) regions in CONUS. Interesting results were obtained for type 2 (type 3) interactions as the effects of ENSO phases were opposite (similar but enhanced), compared to individual analysis of ENSO, when associated with the phases of PDO/AMO/NAO. The results provide several new findings and useful information for forecasting of water resources in the CONUS region. © 2021