Published online on January 2020
Abstract: Accurate and practical direct envelope equations for moving load analysis are needed these days for many reasons. Over or under estimating the load capacity in pre-stressed bridge girders may raise concerns about safety and serviceability. Moreover, direct envelope equations lead to efficient and economical design of bridge structures. Finally, these equations can provide more accurate results compared to those obtained using a commercial software program. This study develops direct envelope analysis equations for moving loads on bridge girders. The analysis consists of maximum positive support moments, positive and negative shear envelope equations, negative moment envelope equations and maximum point of deflection. The analysis is based on one dimensional slope moment matrix method designed to calculate support moments of structural members. Maximum point of deflection is based on general deflection equation. Fixed and pinned end support conditions are applied since there is no cantilever bridge girder. Detailed Comparison between this paper results and commercial software program (STAAD) will be made to prove their accuracy and practicality. Most of the commercial software programs have been concentrated on interval distance calculation of moving load analysis. In comparison, this study is conducted on the continuous moving of wheel loads (interval distance is equal zero); hence the calculations obtained are more accurate.
International Journal of Bridge Engineering, Vol. 7, No. 3, 2019: pp. 1-22
Jay D. Gohel, Siddharth G. Shah
Abstract: Due to the introduction of high speed train in the world, the interest in Dynamic behavior has increased. According to current scenario, HST (High Speed Train) is under construction more than ten countries including India. The existing bridges in India are designed according to Indian bridge codes in which the dynamic behavior of high speed train is added by including dynamic impact factor. Dynamic impact factor is a function of loaded length only. However dynamics response of bridge involves a number of parameter like frequency characteristics of bridge structure (i.e. the length, mass, rigidity of individual member), the frequency characteristics of vehicle (i.e. the sprung and unsprung masses, the stiffness of spring), the damping in bridges and vehicles, track irregularities, and the velocity of vehicle and so on. This paper represents the analytical study carried out on existing Railway Bridge to know the dynamic behavior of Railway Bridge under the increasing speed of train.
International Journal of Bridge Engineering, Vol. 7, No. 3, 2019: pp. 23-31
Osama Mohammed Elmardi Suleiman
Abstract: First – order orthotropic shear deformation equations for the nonlinear elastic bending response of rectangular decks plates are introduced. Their solution using a computer program based on finite differences implementation of the Dynamic Relaxation (DR) method is outlined. The convergence and accuracy of the DR solutions for elastic large deflection response of isotropic, orthotropic, and laminated plates are established by comparison with various exact and approximate solutions. The present Dynamic Relaxation method (DR) coupled with finite differences method shows a fairly good agreement with other analytical and numerical methods used in the verification scheme. It was found that: The convergence and accuracy of the DR solution is dependent on several factors including boundary conditions, mesh size and type, fictitious densities, damping coefficients, time increment and applied load. Also, the DR large deflection program using uniform finite differences meshes can be employed in the analysis of different thicknesses for isotropic, orthotropic or laminated plates under uniform loads. All the comparison results for simply supported (SS4) edge conditions showed that deflection is almost dependent on the direction of the applied load or the arrangement of the layers.
International Journal of Bridge Engineering, Vol. 7, No. 3, 2019: pp. 33-48
Theodore G. Konstantakopoulos, George T. Michaltsos
Abstract: The present work studies the behavior of a suspended arch bridge under the action of concentrated or distributed moving loads, proposing a mathematical model for the problem. The studied suspended arch bridge has a dense arrangement of cables, while the described method can easily be extended in the case of a sparse arrangement of cables. Two models are considered for the study of the bridge, a 2D model and a 3D one, while the theoretical formulation, is based on a continuum approach, that has been used in the literature to analyze such bridges. Finally the obtained equations are solved using the Duhamel’s integrals and the Laplace Transform.
International Journal of Bridge Engineering, Vol. 7, No. 3, 2019: pp. 49-72