Department of Civil Engineering

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End date: 2009Subject: search.filters.subject.Civil Engineering

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Now showing 1 - 10 of 77
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    Optimum assignment of trains to platforms under partial schedule compliance
    (Elsevier, 2008) Vikram, Durgesh
    The paper develops a linear mixed integer programming formulation for allocating platforms optimally to trains arriving at a busy multi-platform station. The formulation does not assume that all trains arrive as per schedule, in fact it assumes that the exact arrival times of trains are known shortly (an hour or so) before the actual arrivals of the trains. Such variation in arrival times often necessitates delaying of trains (on the entry tracks) due to non-availability of platforms; these delays may also cause queuing up of trains on the tracks. While determining the optimum allocation the formulation takes into account the inconvenience caused due to (i) delay, (ii) allocation of non-preferred platforms (some platforms may be preferred for some trains – as is the case in India), and (iii) last minute reassignment of platforms. The constraints ensure that all physical and safety related restrictions are satisfied. Various problems developed from the schedule of arrivals at a busy station in India are also solved and the results analyzed.
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    Multiphase models for simulating hot and slightly miscible DNAPL (dense non-aqueous phase fluids) in a saturated rock fracture under deformation
    (IWA, 2009) Jha, Shibani K
    In the present study a two dimensional model is first developed to show the behaviour of dense non-aqueous phase liquids (DNAPL) within a rough fracture. To consider the rough fracture, the fracture is imposed with variable apertures along its plane. It is found that DNAPL follows preferential pathways. In next part of the study the above model is further extended for non-isothermal DNAPL flow and DNAPL-water interphase mass transfer phenomenon. These two models are then coupled with joint deformation due to normal stresses. The primary focus of these models is specifically to elucidate the influence of joint alteration due to external stress and fluid pressures on flow driven energy transport and interphase mass transfer. For this, it is assumed that the critical value for joint alteration is associated with external stress and average of water and DNAPL pressures in multiphase system and the temporal and spatial evolution of joint alteration are determined for its further influence on energy transport and miscible phase transfer. The developed model has been studied to show the influence of deformation on DNAPL flow. Further this preliminary study demonstrates the influence of joint deformation on heat transport and phase miscibility via multiphase flow velocities. It is seen that the temperature profile changes and shows higher diffusivity due to deformation and although the interphase miscibility value decreases but the lateral dispersion increases to a considerably higher extent.
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    Dynamic instability analysis of laminated composite stiffened shell panels subjected to in-plane harmonic edge loading
    (Korea Science, 2006) Patel, S. N.
    The dynamic instability characteristics of laminated composite stiffened shell panels subjected to in-plane harmonic edge loading are investigated in this paper. The eight-noded isoparametric degenerated shell element and a compatible three-noded curved beam element are used to model the shell panels and the stiffeners respectively. As the usual formulation of degenerated beam element is found to overestimate the torsional rigidity, an attempt has been made to reformulate it in an efficient manner. Moreover the new formulation for the beam element requires five degrees of freedom per node as that of shell element. The method of Hill's infinite determinant is applied to analyze the dynamic instability regions. Numerical results are presented to demonstrate the effects of various parameters like shell geometry, lamination scheme, stiffening scheme, static and dynamic load factors and boundary conditions, on the dynamic instability behaviour of laminated composite stiffened panels subjected to in-plane harmonic loads along the boundaries. The results of free vibration and buckling of the laminated composite stiffened curved panels are also presented.
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    Buckling and dynamic instability analysis of stiffened shell panels
    (Elsevier, 2006-03) Patel, S. N.
    The static and dynamic instability characteristics of stiffened shell panels subjected to uniform in-plane harmonic edge loading are investigated in this paper. The eight-noded isoparametric degenerated shell element and a compatible three-noded curved beam element are used to model the shell panels and the stiffeners, respectively. As the usual formulation of degenerated beam element is found to overestimate the torsional rigidity, an attempt has been made to reformulate it in an efficient manner. Moreover, the new formulation for the beam element requires five degrees of freedom per node as that of shell element. The method of Hill's infinite determinant is applied to analyze the dynamic instability regions. Numerical results are presented through convergence and comparison with the published results from the literature. The effect of various parameters like shell geometry, stiffening scheme, static and dynamic load factors, stiffener size and position, and boundary conditions are considered in buckling and dynamic instability analysis of stiffened panels subjected to uniform in-plane harmonic loads along the boundaries.
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    Dynamic stability analysis of stiffened shell panels with cutouts
    (ASCE, 2009-04) Patel, S. N.
    A finite element dynamic instability analysis of stiffened shell panels with cutout subjected to uniform in-plane harmonic edge loading along the two opposite edges is presented in this paper. The eight-noded isoparametric degenerated shell element and a compatible three-noded curved beam element are used to model the shell panels and the stiffeners, respectively. As the usual formulation of degenerated beam element is found to overestimate the torsional rigidity, an attempt has been made to reformulate it in an efficient manner. Moreover the new formulation for the beam element requires five degrees of freedom per node as that of shell element. Bolotin method is applied to analyze the dynamic instability regions. Numerical results of convergence studies are presented and comparison is made with the published results from literature. The effects of various parameters such as shell geometry, radius of curvature, cutout size, stiffening scheme, and dynamic load factors are considered in dynamic instability analysis of stiffened shell panels with cutout. The free vibration and static stability (buckling) results are also presented. With the consideration of radius of curvatures the panels reduce from deep shell case to shallow shell case and finally become flat plate.
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    Parametric study on the dynamic instability behaviour of laminated composite stiffened plate
    (ASCE, 2009-11) Patel, S. N.
    This paper deals with the study of dynamic or parametric instability behavior of laminated composite stiffened plates with step-uniform and concentrated in-plane harmonic edge loading. The eight-noded isoparametric degenerated shell element and a compatible three-noded curved beam element are used to model the plate and the stiffeners, respectively. The method of Hill’s infinite determinant is applied to analyze the dynamic instability regions. Numerical results are presented through convergence and comparison with the published results from the literature. The effects of parameters like loading type, stiffening scheme, lamination scheme, dynamic load factor, and boundary conditions are considered in the dynamic instability analysis of laminated composite stiffened plate. It has been shown that the type of loading and the width of loading have remarkable effect on the dynamic instability characteristics of the stiffened plate.
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    Soil Bearing Capacity Determination using Ultrasonics
    (Journal of Pure and Applied Ultrasonics, 2000) Kumar, Kamalesh
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    A Procedure for the Evaluation of Coupling Beam Characteristics of Coupled Shear Walls
    (Asian Journal of Civil Engineering, 2007) Bhunia, Dipendu
    The behavior of coupled shear walls is governed by coupling beams. This paper presents a simple technique for the purpose of design to determine an appropriate level of yield moment capacity for the coupling beams. This technique is checked against nonlinear static pushover analysis performed using DRAIN-3DX for the usual case of symmetric coupled shear walls with different types of coupling beams. The assumption of pinned base in the shear walls with steel coupling beams yields results which agree closely with those of DRAIN-3DX. For the case of fixed base shear walls, the design technique is expected to be conservative
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    Pore fluid effect on shear strength of Pilani soil
    (Journal of the Institution of Engineers, 2001) Kumar, Kamalesh
    Soil strength and its accurate determination are always important issues to a soil engineer. Pore fluid and its characteristics are found to have significant effect in modifying shear strength parameters. Present study focuses on effect of pore fluid quantity and its electrolyte concentration on shear strength parameters of soil samples collected locally. Soil samples of specific particle size were subjected to direct shear testing when pore water content and its electrolyte concentration was changed. Variation of cohesion and angle of internal friction with above parameters was thus studied. Cohesion and angle of internal friction can be determined conveniently and accurately and provide valuable information about shear strength status of soil samples when pore water content and electrolyte concentration of pore water of the soil system changes. Thus optimum level of pore water quantity and electrolyte concentration in it has been determined to obtain optimum shear strength of soil mix tested.