Journal Articles
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Item A review of multi-scale modelling of concrete deterioration: Fundamentals, techniques and perspectives(Elsevier Ltd, 2023) Barbhuiya, S.; Jivkov, A.; Das, B.B.The properties of concrete are degraded during service by coupled physical and chemical processes that operate at several length scales, and the prediction of its performance in engineering structures requires multi-physics, multi-scale modelling approaches. The aim of this paper is to provide a comprehensive overview of the current modelling techniques for analysis of concrete deterioration. The paper covers the fundamentals of modelling at several length scales, as well as the bridging/transition between scales, and the numerical methods based on continuum and discrete formulations appropriate to different scales. Considered are the key chemical and physical deterioration processes of carbonation, chloride ingress, freeze–thaw damage, and abrasion. The paper also reviews the validation and verification of multi-scale models and discusses future trends such as data science integration and sustainable concrete design. It is expected that the information presented here will be a valuable resource for researchers and practitioners in the field, highlighting advancements and stimulating future research in multi-scale modelling of concrete deterioration. © 2023 Elsevier LtdItem Parametric studies were carried out to analyse the effect on sea water intrusion of freshwater recharge through a finite width strip parallel to the coast. A vertically integrated one-dimensional finite element model was used for this purpose. The studies included the analysis of the effect of location, width, intensity and the period of recharge on sea water-freshwater interface motion. Relationships were established between the interface motion and the recharge parameters applicable to wide ranging practical cases. From the studies, the ideal location for recharge was identified to achieve the maximum repulsion of intrusion. The width of recharge also affects the interface motion and the widths greater than 2% of the initial intrusion length were effective in controlling the intrusion. The results indicated that the reduction of intrusion up to 30% could be achieved through strip recharge. © 2001 Taylor & Francis Group, LLC.(Effect of strip recharge on sea water intrusion into aquifers; Effet d’une bande de recharge sur l’intrusion d’eau de mer dans les aquifères) Mahesha, A.2001Item The objective of the present study is to predict analytically the material perforation under hyper velocity impact. Hyper velocity impact is a complex phenomenon involving wave propagation, penetration and responses exceeding elastic limits, leading to hydrodynamic behaviour. A general-purpose program (GPP) that permits a combination of non-linear finite element technique and explicit integration scheme, is employed for the simulations. The geometry of perforation is computed for various projectiles with different incident angles, impact velocities and materials. The computed values are compared with test results available in the literature. The results indicate excellent agreement with the measurements and give good insight into the effect of various parameters on the perforation size and geometry.(Perforation under hyper velocity impact - A prediction using finite element technique) Suhas, M.; Samgeeth, R.; Veenaranjini, S.M.; Singh, G.2005Item Effect of permeability of subsurface barrier on salt water intrusion in coastal aquifers(2006) Mahesha, A.; Lakshmikant, K.Semi-pervious, subsurface barriers are considered to be one of the viable solution for the control of saltwater intrusion in coastal aquifers. Investigations are carried out in this work to assess the performance of the barrier with different permeabilities using a finite element model. The advancement of saltwater - freshwater interface and the water table profiles are monitored for fresh water withdrawals at inland locations under the scenarios of wide ranging hydraulic conductivities of the barrier. The results indicated that barrier is able to check the advancement of the intrusion significantly with the hydraulic conductivity being less than certain limit. The performance of the barrier is also compared with no barrier conditions. Marked variations in the interface and water table profiles are observed as compared to no barrier condition. The performance of the barrier was not found to be satisfactory beyond certain limit of permeability.Item Dynamic response of railroad vehicle to rail joints and average vertical profile: A time domain approach(Inderscience Publishers, 2007) Gangadharan, K.V.; Sujatha, C.; Ramamurti, V.One rigid body and three finite element models have been used to study the dynamic behaviour of a typical Electrical Multiple Unit Trailer coach running on Indian suburban tracks. Following eigenvalue analysis, dynamic responses to input excitation from rail joints and Average Vertical Profile (AVP) have been determined in the time domain, using mode superposition technique. Acceleration and displacement response at Centres of Gravity (eg) of car and bogie have been predicted. The analytical results compare well with experimental results and highlight the need to include superstructure elasticity to predict the dynamic response accurately. Copyright © 2007 Inderscience Enterprises Ltd.Item Effect of boundary conditions and convection on thermally induced motion of beams subjected to internal heating(2007) Malik, P.; Kadoli, R.; Ganesan, N.Numerical exercises are presented on the thermally induced motion of internally heated beams under various heat transfer and structural boundary conditions. The dynamic displacement and dynamic thermal moment of the beam are analyzed taking into consideration that the temperature gradient is independent as well as dependent on the beam displacement. The effect of length to thickness ratio of the beam on the thermally induced vibration is also investigated. The type of boundary conditions has its influence on the magnitude of dynamic displacement and dynamic thermal moment. A sustained thermally induced motion is observed with progress of time when the temperature gradient being evaluated is dependent on the forced convection generated due to beam motion. A finite element method (FEM) is used to solve the structural equation of motion as well as the heat transfer equation. © Springer-Verlag 2007.Item Combined optimisation simulation model for groundwater management policy options(2007) Yaragal, S.C.; Nagaraj, M.K.Water resources system being quite complex in-nature, modelling involves several variables and parameters. A large number of models have been developed for analysis of water resources system. Most of the models developed are of simulation optimisation type. In general water management models which generally use the governing partial differential equation of now, the problem is formulated using either finite difference techniques or finite element method. In this paper, a hybrid model is formulated which simulates the groundwater system and optimises the same. The model developed has been used to study the effects of variation in pumping factors on the optimal values and on the yearly yield from the system, for a chosen pattern of pumping. The model has been analysed for three different boundary conditions. The aquifer model is descritised into 64 grids and a particular pumping pattern is chosen in the present study. The governing partial differential equation for groundwater now is reduced to algebraic linear equations using finite differences scheme and they are then embedded as a set of constraints in the model. For the chosen pumping pattern, the pumping factor plays a key role, depending on the boundary conditions, in achieving an optimum solution. Here, minimisation of heads is considered for optimisation. The model helps in simulating a complex groundwater system and evaluating certain policy for groundwater management.Item Dynamic response of railroad vehicles: A frequency domain approach(Inderscience Publishers, 2008) Gangadharan, K.V.; Sujatha, C.; Ramamurti, V.A very elaborate Finite Element (FE) model and a rigid body model of a typical electrical multiple unit trailer coach are described. These models were used to find the dynamic response to track irregularities in the frequency domain. The Power Spectral Density (PSD) of track irregularities was used as input to the system. The influence of different track irregularities on dynamic response and coupling between vertical and lateral dynamics was investigated. Extensive experiments were carried out, and analytical results were compared with the measured response. Copyright © 2008 Inderscience Enterprises Ltd.Item Simulation of varada aquifer system for sustainable groundwater development(2008) Ramesh, H.; Mahesha, A.Groundwater flow modeling has been used extensively worldwide with varying degrees of success. The ability to predict the groundwater flow is critical in planning and implementing groundwater development projects under increasing demand for fresh water resources. This paper presents the simulation of the aquifer system for planning the groundwater development of Varada basin, Karnataka, India using the Galerkin finite-element method. The government of Karnataka State, India is implementing the World Bank assisted project, "Jal Nirmal" for a sustainable development of the region, thereby ensuring a safe supply of drinking water to the northern districts of the state. Varada basin is one of the beneficiaries of the project in Haveri district. Field tests carried out in the study area indicate that the region is predominantly a confined aquifer with transmissivity and storage coefficients ranging from 5.787×10-6m2/s (0.500 m2/day) to 4.213×10-3m2/s (3.640×102m2/day) and 0.011-0.001× 10-2, respectively. This study mainly emphasizes the spatial and temporal variability of groundwater potential under different developmental scenarios. The model predictions were reasonably good with correlation coefficients ranging from 0.78 to 0.91 with the root mean square error of about 0.46-0.78 during calibration and validation. The stated accuracies are based on comparisons between measured and calculated heads. The outcome of the study would be a useful input for the conjunctive use of surface water and groundwater planning for the sustainable development of the region. © 2008 ASCE.Item Static analysis of functionally graded beams using higher order shear deformation theory(2008) Kadoli, R.; Akhtar, K.; Ganesan, N.Displacement field based on higher order shear deformation theory is implemented to study the static behavior of functionally graded metal-ceramic (FGM) beams under ambient temperature. FGM beams with variation of volume fraction of metal or ceramic based on power law exponent are considered. Using the principle of stationary potential energy, the finite element form of static equilibrium equation for FGM beam is presented. Two stiffness matrices are thus derived so that one among them will reflect the influence of rotation of the normal and the other shear rotation. Numerical results on the transverse deflection, axial and shear stresses in a moderately thick FGM beam under uniform distributed load for clamped-clamped and simply supported boundary conditions are discussed in depth. The effect of power law exponent for various combination of metal-ceramic FGM beam on the deflection and stresses are also commented. The studies reveal that, depending on whether the loading is on the ceramic rich face or metal rich face of the beam, the static deflection and the static stresses in the beam do not remain the same. © 2007 Elsevier Inc. All rights reserved.