Civil Engineering

Shiv Nadar University is a comprehensive, multidisciplinary, research-focused, and student-centric University offering a full range of academic programs at the undergraduate, postgraduate and doctoral level. With state-of-the-art infrastructure, the University comprises of academic wings, sophisticated labs, international standard sports facilities, amphitheaters, auditorium, conference rooms and smart classrooms. The University&rsquo;s goal is to become internationally recognized for the quality of its research and creative endeavors and their applicability to improving quality of life, generating new insights and expanding the boundaries of human knowledge creativity. Committed to excellence in teaching, research and service, the University aims to serve the higher education needs of India and the world beyond.

Shiv Nadar University

This review article, dedicated to the bicentenary celebration of Sir George Gabriel Stokes’ birthday, presents the state-of-the-science of terminal fall velocity, highlighting his rich legacy from the perspective of fluvial hydraulics. It summarizes the fluid drag on a particle and the current status of the drag coefficient from both the theoretical and empirical formulations, highlighting the three major realms—Stokesian, transitional and Newtonian realms. The force system that drives the particle motion falling through a fluid is described. The response of terminal fall velocity to key factors, which include particle shape, hindered settling, and turbulence (nonlinear drag, vortex trapping, fast-tracking, and effects of loitering), is delineated. The article puts into focus the impact of terminal fall velocity on fluvial hydraulics, discussing the salient role that the terminal fall velocity plays in governing the hydrodynamics of the sediment threshold, bedload transport, and suspended load transport. Finally, an innovative perspective is presented on the subject’s future research track, emphasizing open questions.

(SoE) School of Engineering

Proceedings of the Royal Society A

Terminal fall velocity: the legacy of Stokes from the perspective of fluvial hydraulics

For electro-mechanical impedance (EMI) technique based Structural Health Monitoring (SHM), the piezo ceramic patches are employed with adhesive bond to evaluate and diagnose the host structure to be monitored. The adhesive bond forms a definite layer for force transmission between the patch and host structure. The mechanical and geometrical properties of the adhesive bond layer has significant effect on the overall performance of the PZT-structure interaction. This paper represents the effect geometrical deformation bonding area in the coupled admittance signature through mathematical modelling. The debonding effect has modelled for piezo elasto-dynamic system. In this paper, the mathematical modelling for 1D piezo elastic structure for debonding case and the results are compared with perfect bonding and definite bonding of adhesive bond for PZT-Structure interaction. The paper also studied parametric variation of bond parameter to examine the influence on the EMI based structural signature. © 2019 IEEE.

7th International Youth Conference on Energy, IYCE 2019

One-Dimensional Modelling of Piezo-Structure Interaction for DeBonding Configuration using Electro-Mechanical Impedance (EMI) Techniques

India currently has 5264 large dams in operation and 437 large dams under construction. Many of these dams do not match the emerging hydro-meteorological, hydraulic aspects. Safety of these dams is important to prevent collapse triggered by climate change effects. The increase in inflows to dams due to cloud bursts may cause dam safety concerns due to enhanced hydrodynamic forces. The main focus of this review is to get an insight into the events of cloud burst and GLOF which threaten dam safety. There are 65 completed and 11 under construction dams in India in the category of "Dams of National Importance" of which 22\% of the completed projects are older than 25 years. The review on failure due to cloud burst on few dams nationally and internationally has been done. The behaviour of Tehri Dam and Nathpa Jhakri dam in the past during the Cloud burst and GLOF occurrences and the importance to have a storage capacity for the hydel dams has been discussed along with the discussion on the necessity to increase the spillway capacity of Matatila dam. The scientific tools for conducting incisive case studies are highlighted to develop adaptive measures to deal with the resulting circumstances. © 2019, Central Board of Irrigation and Power. All rights reserved.

Center for Environmental Sciences & Engineering

Water and Energy International

Review of climate change impacts on dam safety and flood mitigation issues in India

Constant rate of strain (CRS) consolidation test is a fast test method to characterize consolidation behavior of fine grained soils. In this test method, the test specimen is deformed at a constant rate of deformation, and pore water pressure at the base of the test specimen and axial reaction load are measured at successive interval during the test. This test method has several advantages over traditional incremental loading consolidation test. In the present research, a series of CRS consolidation tests have been performed on reconstituted samples of eight different clayey soils with different plasticity indices. The suitable strain rate at which the test is to be performed has been decided considering the criterion given in the literature. The test data obtained from these tests have been analyzed through the method of interpretation given in ASTM: D4186-06 (Standard Test Method for One-Dimensional Consolidation Properties ofSaturated Cohesive Soils Using Controlled-Strain Loading. 2008). The present study shows that the existing method of interpretation yields unreliable results for a significant duration at early stage of the test despite of performing the test at recommended strain rate. Analysis of present experimental data and some of the available recommendations to select suitable strain rate indicates that the theory for CRS consolidation which forms the basis for the existing method of interpretation is unable to describe rapid evolution of pore-water pressure at early stage of the test. Because of this, the existing method of interpretation fails to interpret the consolidation parameters accurately throughout the test. © 2019, Springer International Publishing AG, part of Springer Nature.

Sustainable Civil Infrastructures

Issues in Interpretation of Constant Rate of Strain Consolidation Test Data

The suspension strut cap is the major component of automobile, which attaches the suspension strut to the vehicle body. In addition, it insulates the tire noise & vibrations from the vehicle for generated due to rough road profile and speed breakers. The suspension cap is mounted at the top of suspension strut, where one side bolts to the vehicle (i.e. cap is directly attached to the body) and the other side to attached to the steering pivots of wheel. So as the vehicle moves and goes over bumps, the up & down impact pushes and pulls at the mount. The caused vibration can be transmitted into the vehicle if routine inspection has not been done and can cause wear and tear in bearing part of the mount (loosening of bolts). The damaged suspension cap can lead to clunking noises, noisy steering, excessive movement, tire alignment etc. Hence, conditional health monitoring of a suspension strut cap is vital in vehicles. For this study, the utilizations of dual sensing mechanism of piezo sensor has made for Structural health monitoring (SHM) technique i.e. Electro-Mechanical Impedance Technique. Different state of damage has been induced by loosening the bolts to different torque range and compared with pristine stage (when bolts are tightened to highest force). The admittance signature are plotted to verify the damage condition raised due self-loosening. The RMSD plots were drawn to quantify the level of damage. Finally the FE coupled simulation has done for the suspension strut mound with surface bonded PZT patch for different damage levels and results are compared with experimental results. The promising results for this study sets a new paradigm for SHM technologies. © 2019 9th ECCOMAS Thematic Conference on Smart Structures and Materials, SMART 2019. All rights reserved.

9th ECCOMAS Thematic Conference on Smart Structures and Materials, SMART 2019

Condition health monitoring of a suspension strut cap/ upper strut mount using piezoelectric sensor for electro-mechanical impedance technique

Hydration of concrete is a very complicated and multiphase process, where the cement gel transforms into a hardened state from plastic/semiplastic phase. Proper progression of the hydration process ensures the development of targeted mechanical properties such as the elastic modulus, the coefficient of thermal expansion, the Poisson’s ratio, and finally, the characteristic strength of concrete. Concrete experiences large thermal variations during the early phase of hydration due to the heat generated during the formation of cement hydration compounds, which contributes to shrinkage and cracking, somewhat making ground for the ultimate failure in the long run. Therefore, it is utmost important to monitor the progression of hydration for enhancing performance during the curing and the early service life. This article presents a new reusable external configuration of piezo-impedance transducers to monitor the hydration process in concrete structures using the electro-mechanical impedance technique. The proposed configuration consists of a thin metal foil instrumented with piezoelectric ceramic patch at the free end with the other end of the foil embedded inside the concrete. This configuration is compared against a piezoelectric ceramic patch directly bonded on the rebar used for reinforcement and another one embedded in the concrete surrounding the rebar. The sensing capability of the proposed metal foil configuration is clearly evident from the coupled admittance signature quantitatively vis-à-vis the other configurations. As a preliminary analysis, root mean square deviation values are employed to monitor the hydration process quantitatively. A piezo-equivalent mechanical model is also developed wherein the piezo-identified mass, stiffness and damping parameters are investigated for the cement hydration process so as to chalk out rigorous quantifiers of hydration progression. The employability of the proposed configuration is further proven by explanation of the physio-chemical products developed during various stage of hydration with step-by-step explanation along with corelation of the piezo-identified mass, stiffness and damping parameters. Overall, the proposed reusable configuration carries a high potential for field deployment in concrete industry for early detection of physio-chemical changes. © The Author(s) 2019.

World University root node

Fulltext

Journal of Intelligent Material Systems and Structures

Development and evaluation of an external reusable piezo-based concrete hydration-monitoring sensor

In this paper, we present an alternative solution of consolidation at constant rate of deformation (CRD). Governing equation of CRD consolidation is formulated considering excess pore water pressure as primary variable. Formulation of the governing equation is done for soil as linear as well as nonlinear materials. An analytical solution to the governing equation is derived which consists of transient state and steady state components. The solution derived herein yields profile of excess pore water pressure distribution with depth at any time during the test. The present paper analyzes the excess pore water pressure distribution profile during CRD consolidation and factors affecting it in detail. Analysis of the obtained solution indicates the existence of moving boundary condition within the test specimen at early stage of the test where transient state condition prevails. It also indicates that the pore water pressure ratio affects significantly the excess pore water distribution profile, in turn, average value of pore water pressure and average effective stress in the specimen. An expression for consolidation parameters for steady state condition are derived using the present solution. Further, evolution of excess pore water pressure at the base of CRD consolidation test specimen during the test is predicted for normally consolidated as well as for over consolidated soils at different rates of deformation. © 2018, Springer Nature Switzerland AG.

Geotechnical and Geological Engineering

Alternative Analytical Solution of Consolidation at Constant Rate of Deformation

The turbulence characteristics within flows over water-worked gravel beds (WGBs) and screeded gravel beds (SGBs) were examined by measuring the instantaneous flow velocity field using a two-dimensional particle image velocimetry system. To compare the responses of a WGB and an SGB to velocity and various turbulence characteristics, the flow Froude number was kept identical for both the beds that remained immobile. The roughness structures of both the beds were measured using a laser scanner. The results showed that the bed surface roughness was higher in the WGB than in the SGB. However, the longest axis of the gravels of WGBs was oriented streamwise owing to the action of water work, but the gravels of SGBs were randomly poised. The distribution of bed roughness fluctuations was negatively skewed in the WGB and positively skewed in the SGB. Double averaging methodology was applied to analyze the flow parameters. In this paper, the vertical profiles of the double-averaged streamwise velocity and the turbulence parameters, specifically the spatially averaged (SA) Reynolds shear and normal stresses, form-induced shear and normal stresses, turbulent kinetic energy (TKE) and form-induced TKE fluxes, quadrant analysis of SA Reynolds shear stress, etc., are presented and analyzed critically by focusing on comparisons between a WGB and an SGB. A comparative study reveals that in the near-bed flow zone, the SGB underestimates the turbulence parameters compared to the WGB. Therefore, in order to represent the prototypical flow in laboratory, the experiments should be performed in a WGB.

Physics of Fluids

Hydrodynamics of water-worked and screeded gravel beds: A comparative study

The authors regret that: (1) the footnote (a) in Tables 4a, 5a, 4b and 5b requires an amendment due to insufficient information on the sources of RfC, and (2) the RfC values of Cd and Hg listed in Table 5a are not consistent with those in Table 4a due to an oversight. (1) The amended footnote (a) in 4a and 5a is given below: aThe inhalation reference concentration (RfC) values of Be and Hg were obtained from US EPA Integrated Risk Information System (IRIS) (www.epa.gov/iris), and that of Cd from the California EPA, the office of Environmental Health Hazard Assessment (OEHHA) (https://oehha.ca.gov). The RfC of Pb was not established by the US EPA. Instead, the US EPA Ambient Air Quality Standard set for Pb (0.15 μg/m3) was considered to be the RfC value by the authors.(2) The amended footnote (a) in 4b and 5b is given as follows: aThe unit risk factor (URF) values of As, Cd, Cr(VI), and Ni were obtained from the US EPA Integrated Risk Information System (IRIS) (www.epa.gov/iris), and those of Be, and Pb from the California EPA, the office of Environmental Health Hazard Assessment (OEHHA) (https://oehha.ca.gov). The correct RfC values (mg/m3) of Cd, and Hg included in Table 5a are 2.0 × 10− 5 (instead of 2.1 × 10− 5), and 3.0 × 10− 4 (instead of 3.2 × 10− 5), respectively as they appear in Table 4a.The authors apologize for any inconvenience caused. © 2017

Science of the Total Environment

Corrigendum to “Human health risk associated with exposure to toxic elements in mainstream and sidestream cigarette smoke” [Sci. Total Environ. 472, 947 − 956, 2014](S0048969713013466)(10.1016/j.scitotenv.2013.11.063)

Structures made of variable stiffness (VS) composites possess a rich design space for bistable configurations that demonstrate different values of curvatures and out-of-plane displacements. In this study, several VS composites are investigated which can yield cylindrical bistable shapes similar to those generated from unsymmetrical cross-plies. Such configurations have been found favorable as a component for certain morphing applications. A semi-analytical model based on the Rayleigh-Ritz approach is presented to calculate the thermally induced multistable shapes as well as the snap-through forces particularly taking into account the curvilinear paths of VS composites. A nonlinear finite element analysis is performed to check the accuracy of the semi-analytical method. Cylindrical shapes generated from VS laminates and the corresponding straight fiber cross-ply laminates are analyzed and compared. The snap-through forces are subsequently calculated and compared for different VS laminates and the straight fiber cross-ply. It is observed that certain VS composites have a significant reduction of snap-through forces but with a marginal difference in out-of-plane displacement as compared to the corresponding straight fiber cross-ply laminate.