A comprehensive study of approaches for the estimation of the local average of the received signal strength (RSS) for indoor multipath propagation is presented. The effects of the required number of the RSS data samples and the Euclidean distances between the neighboring samples are investigated over 1D, 2D, and 3D configurations. It was found that the effect of fast fading was reduced to an acceptable level using a 2D horizontal arrangement with a relatively large spacing configuration. Furthermore, averaging was enhanced with a larger spacing compared to smaller spacing when considering the same number of samples.

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Journal: IEEE Access, volume 7,

A fast analysis approach was developed to improve the computational efficiency of seismic analysis for structures under non-stationary seismic excitations. A high-pier railway bridge was selected as a case study to evaluate the proposed fast approach. First, non-stationary excitation was translated into a series of deterministic transient analyses. Second, a modified high-precision integration method was introduced to reduce the number of transient analyses to two. Finally, a seismic response analysis of the high-pier railway bridge subjected to non-stationary ground motions was conducted with the secondary development platform of the general finite element software ANSYS. The fast analysis technique and ANSYS were combined. The results show the proposed fast analysis technique can model seismic non-stationary and spatial variability and can be easily extended to practical engineering application

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Journal: Structural Engineering International, Volume 25, Number 4, pp. 414-418(5)

The paper states development and application of novel dynamic state estimation based methods for estimation of parameters of vibrating engineering structures. The study investigates strategies for data fusion from multiple tests of possibly different types and different sensor quantities through the introduction of a common pseudo-time parameter. These strategies have been developed within the framework of Kalman and particle filtering techniques. The proposed techniques are applied to a suite of problems that includes laboratory and field studies with a primary focus on finite element model updating of bridge structures and vehicle structure interaction problems. The study also describes how finite element models residing in commercially available softwares can be made to communicate with database of measurements via a particle filtering algorithm developed on the Matlab platform.

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Journal: Structural Engineering International, Volume 19, Number 4, 2009, pp. 370-374(5).

The aim of the paper’s project was to select by means of conceptual design and to examine by finite element analysis and analytical models the effectiveness of a precast prestressed beam-column concrete connection of a jointed system and to discuss alternative solutions. Various choices of structural solutions were to be studied within the project with regard to serviceability, production methods, maintenance and costs. The works should include literature studies and FE-analyses with the DIANA V9 program. This thesis presents the results of the finite element analysis to examine the effectiveness of a precast prestressed beam-column concrete connection of a jointed system and compares it with an analytical model.

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Journal: Structural Engineering International, Volume 15, Number 3, 2005, pp. 129-134(6)

a new reliability analysis technique is developed for uncertain structures based on a hybrid uncertain model. Random distributions are used to deal with the uncertainty, while some key parameters in the distribution functions are given variation intervals instead of precise values. Two kinds of hybrid reliability models are constructed based on the reliability index approach (RIA) and the performance measurement approach (PMA), in which the reliability index interval and the target performance interval are employed to evaluate the reliability degree of an uncertain structure, respectively. A monotonicity analysis is conducted for the probability transformation process, which indicates that the extreme values of the limit-state function generally correspond to the bound combinations of the interval parameters. Based on the monotonicity analysis, two efficient algorithms are then formulated to solve the suggested RIA-based and PMA-based hybrid reliability models, in which the outer-layer optimization in terms of random variables and the inner-layer optimization in terms of interval parameters are executed by turns. Three numerical examples are presented to demonstrate the effectiveness of the present method, which include two simple problems with explicit expressions and one complex engineering application.

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Journal: Structural Engineering International, Volume 14, Number 1, 2004, pp. 37- 41(5)

The study of dynamic response of bridges under the action of moving vehicles provides a tool for structural designing as well as damage identification. Bridge-vehicle interaction is generally modelled through single contact point for mathematical simplicity, although the interaction actually takes place through front and rear wheels. In the present work, dynamic deflection of the bridge modelled through two contact points is investigated for a range of vehicle velocity and wheel to wheel distance. It is observed that for wheelbase to bridge span ratio greater than a certain limit, two contact point model gives significantly different results particularly at higher velocity range. The results, presented in terms of non-dimensional parameters, can be used as a design monograph for any bridge-vehicle-velocity combination

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Journal: Structural Engineering International, Volume 12, Number 2, 2002, pp. 76-79(4)

Closed form expressions for the Green function of flexural vibrations of uniform beams are well known, giving the response at any point in the beam due to harmonic point excitation at any position along the beam. The expressions involve trigonometric and hyperbolic functions. The present work first develops alternative forms for the free–free beam, in terms of the sinusoidal eigenmodes of a pinned–pinned beam plus the rigid body modes. Convergence is assessed by comparison with the well-known classical results for a free–free beam. The analysis is then extended to the case of free–free rectangular plates of arbitrary aspect ratio. The work is motivated by the desirability of employing sinusoidal modes for the structure when undertaking hydroelastic analysis (e.g. for a flexible beam or plate floating in the sea).

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Journal: Structural Engineering International, Volume 10, Number 1, 2000, pp. 8-11(4)

Uncertainties in load and system properties play a significant role in reliability analysis of vibrating structural systems. The subject of random vibrations has evolved over the last few decades to deal with uncertainties in external loads. A well-developed body of literature now exists which documents the status of this subject. Studies on the influ-ence of system property uncertainties on reliability of vibrating structures are, however, of more recent origin. Currently, the problem of dynamic response characterization of sys­tems with parameter uncertainties has emerged as a subject of intensive research. The motivation for this research activity arises from the need for a more accurate assess­ment of the safety of important and high cost structures like nuclear plant installations, satellites and long span bridges. The importance of the problem also lies in understand­ing phenomena like mode localization in nearly periodic structures and deviant system behavior at high frequencies. It is now well established that these phenomena are strongly influenced by spatial imperfections in the vibrating systems. Design codes, as of now, are unable to systematically address the influence of scatter and uncertainties.

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Journal: Structural Engineering International, Volume 8, Number 2, 1998, pp. 42- 45(4)

The field of stochastic structural mechanics is currently an active area of research. The primary concern here lies in the probabilistic modeling of the uncertainties in specifying elastic, mass and geometric properties of the structure. This is in contrast with the goals of the more traditional random vibration studies which primarily focus attention on probabilistic modeling of uncertainties associated with loads such as those caused due to earthquakes, wind and guide way irregularities. The motivation for the study of system randomness arises, on one hand, from the need to make the structural safety assessment more realistic, and, on the other hand, from the need to study associated phenomenological response features such as mode localization and system behavior in higher frequency regions. The latter class of problems is relevant in vibro-acoustic design of vehicles. Besides, the recent developments in the fields of robotics and composite structural materials have provided impetus towards developing generic procedures for handling structural randomness. Problems of linear deterministic structural dynamics have been extensively treated in the existing literature within the frameworks of finite element method using normal mode expansions, transfer matrix method and dynamic stiffness matrix approach. When these methods are to be extended to analyze structures with random material and/or geometric property variations, questions on solutions of random differential and algebraic eigenvalue problems, inversion of random matrix and differential operators and characterization of random matrix products arise. The present thesis aims at contributing new methodologies in achieving some of these extensions.

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Journal: Structural Engineering International, Volume 7, Number 3, 1997, pp. 46- 49(4)

First-order reliability and finite element methods are used to develop a methodology for reliability analysis of structures with stochastically varying properties and subjected to random loads. Two methods for discretization of random fields are examined and the influence of the correlation length of random property or load fields on the reliability of example structures is investigated. It is found that the correlation length of load fields has significant influence on the reliability against displacement or stress limit states. The correlation length of property fields is significant for displacement limit states, but may not be significant for stress limit states. Examples studied include a fixed ended beam with stochastic rigidity and a plate with stochastic elasticity.

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Journal: Structural Engineering International, Volume 6, Number 4, 1996, pp. 55- 59 (5)