Now showing 1 - 10 of 28
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    Behaviour of glass fibre reinforced gypsum wall panel under cyclic lateral loading
    (12-11-2008)
    Janardhana, M.
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    Glass fibre reinforced gypsum (GFRG) wall panel, a composite walling product, is made essentially of formulated gypsum plaster, reinforced with glass fibres. The behaviour of such wall panels under earthquake loading merits investigation. The hollow cores inside the walls can be filled with reinforced concrete to increase the strength and lateral load resistance. The results of experimental test on a full-scale GFRG wall panel, filled with reinforced concrete, and subjected to axial and in-plane reverse cyclic load, are presented in this paper. The experimental specimen is 1.02 m wide and 2.85 m high. Hysteretic behaviour of the wall panel, acting as a shear wall, is discussed. © 2008 Taylor & Francis Group.
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    Analytical model for beam column joint in RC frames under seismic conditions
    (01-10-2003)
    Uma, S. R.
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    Beam column joint in reinforced concrete (RC) frames is a crucial zone, the integrity of which is essential for the satisfactory performance of the whole structure. A new analytical model has been proposed to identify the shear behaviour of joint panel zone. Joint panel zone has been idealised as 2D element subjected to in-plane shear and normal stresses. The shear response of the joint core has been characterised by shear stress - shear strain (deformation) relationship established by softened truss model theory. Inelastic behaviour associated with the slip of longitudinal reinforcement anchored in the joint is represented through bar slippage model. The effect of cyclic load on the total response of the structure is obtained through proper hysteretic modelling of beam, column and joints. The behaviour of joints has been studied by carrying out non-linear dynamic analyses on experimental sub-assemblages under cyclic loads. Good correlation between predicted and test results were obtained.
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    Probabilistic characterization of AHWR Inner Containment using High Dimensional Model Representation
    (01-06-2009) ;
    Chowdhury, Rajib
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    Singh, R. K.
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    Kushwaha, H. S.
    In this paper, uncertainty analysis of Advanced Heavy Water Reactor (AHWR) subjected to an accidental pressure is carried out using a computational tool based on High Dimensional Model Representation (HDMR) that facilitates lower dimensional approximation of the original high dimensional implicit limit state/performance function. The method involves response surface generation of HDMR component functions, and Monte Carlo Simulation. HDMR is a general set of quantitative model assessment and analysis tools for capturing the high dimensional relationships between sets of input and output model variables. It is a very efficient formulation of the system response, if higher order variable correlations are weak, allowing the physical model to be captured by the first few lower order terms. Once the approximate form of the original implicit limit state/performance function is defined, the failure probability can be obtained by statistical simulation. Reliability estimates of AHWR Inner Containment subjected to an internal pressure exceeding the design pressure, considering four stages of progressive failure prior to collapse are presented. © 2009 Elsevier B.V. All rights reserved.
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    Fatigue reliability analysis in time domain for inspection strategy of fixed offshore structures
    (01-02-2000)
    Madhavan Pillai, T. M.
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    The paper describes a methodology for estimation of reliability of fixed offshore structures with respect to fatigue and extreme stress. The failure criteria for fatigue are formulated using fracture mechanics principle and that for extreme stress using API Code. Advanced Second Moment method is used to find the reliability index. The total life of the structure is divided into a set of stationary sea-states, occuring during storms and described by directional power spectrum. The method has been illustrated through application to a typical jacket platform. Usefulness of the methodology for planning in-service inspections has been highlighted.
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    Dynamic behaviour of pile foundations in layered soil medium using cone frustums
    (01-01-2004)
    Jaya, K. P.
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    An analytical method using a cone model is developed to evaluate the impedance functions of pile foundations in a layered soil medium. The dynamic behaviour of piles depends on the nature of the interaction between the piles and the surrounding soil. The soil-pile interaction effect modifies the stiffness of the piles and generates damping through energy radiation to infinity. This modified complex stiffness is called the impedance function. A physical model called a cone frustum is developed to represent the layered soil medium. It is capable of incorporating the complexity of layered soil media and the complicated behaviour of propagating waves. The analytical tool is developed based on wave propagation principles.
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    Seismic behaviour of beam-column joints in RC moment resisting frames: A review
    (01-01-2006)
    Uma, S. R.
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    The beam-column joint is the crucial zone in a reinforced concrete moment resisting frame. It is subjected to large forces during severe ground shaking and its behaviour has a significant influence on the response of the structure. The assumption of joint being rigid fails to consider the effects of high shear forces developed within the joint. The shear failure is always brittle in nature which is not an acceptable structural performance especially in seismic conditions. This paper presents a review of the postulated theories associated with the behaviour of joints. Understanding the joint behaviour is essential for exercising proper judgments in the design of joints. The paper discusses the seismic actions on various types of joints and highlights the critical parameters that affect joint performance with special reference to bond and shear transfer.
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    Fatigue crack growth and fracture studies on straight pipes with circumferential surface notch
    (01-12-2008)
    Gandhi, P.
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    Ramachandra Murthy, D. S.
    Fracture behaviour of piping components used in pressurised heavy water reactors of nuclear power plants are of great importance to ensure safety and integrity against the extreme load conditions. Fracture mechanics approach predicts crack growth behaviour under normal operating conditions and failure load under accidental conditions. Leak-Before-Break concept is used to investigate the structural integrity of the piping components. Experimental investigations were carried out on straight pipes to study their fatigue and fracture behaviour under bending. Fatigue tests were conducted on 406 mm outer diameter straight pipes to study the crack growth with various notch configurations. Fracture tests were also conducted on the pipes, which were tested in fatigue, under monotonic loading for their fracture resistance. A new database on fatigue life of large size carbon steel pipes has been created which will be very useful for integrity assessment of power plant structures. The details of the studies are presented in this paper.
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    Axle load variations and vehicle growth projection models for safety assessment of transportation structures
    (01-01-2007)
    Sriramula, Srinivas
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    The design formulations of pavements and bridges are significantly influenced by the uncertainties associated with the prevailing vehicle weight characteristics. Accurate modelling of load spectra and the estimation of possible vehicle growth and composition are the main components in the safety assessment of transportation structures. The vehicle weights from the existing traffic form the basis for load spectra development, and the vehicle projections are subjective to the socio-economic conditions. In this paper, the methodologies of appropriate data consideration for such representation are discussed and demonstrated based on the data from India. The load spectra are also developed for vehicular data from Interstate 95 (I-95) in New York State. In lieu of the current status of the design codes for pavements and bridges worldwide, most of the developing countries are in need of analogous models for the calibration of the design basis. © 2007 Taylor & Francis Group, LLC. All rights reserved.
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    High dimensional model representation for piece-wise continuous function approximation
    (01-12-2008)
    Chowdhury, Rajib
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    High dimensional model representation (HDMR) approximates multivariate functions in such a way that the component functions of the approximation are ordered starting from a constant and gradually approaching to multivariance as we proceed along the terms like first-order, second-order and so on. Until now HDMR applications include construction of a computational model directly from laboratory/field data, creating an efficient fully equivalent operational model to replace an existing time-consuming mathematical model, identification of key model variables, global uncertainty assessments, efficient quantitative risk assessments, etc. In this paper, the potential of HDMR for tackling univariate and multivariate piece-wise continuous functions is explored. Eight numerical examples are presented to illustrate the performance of HDMR for approximating a univariate or a multivariate piece-wise continuous function with an equivalent continuous function. Copyright © 2007 John Wiley & Sons, Ltd.