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Issue 3: Sep.-Dec.. 2018

Issue 3: Sep.-Dec.. 2018

Published online on January 2019

Optimal Mesh Density for FEM Analysis of a Bridge Deck under Self-Weight and Dynamic Vehicular Loads

Rohit Kumar Dubey

Abstract:Analytical Modelling is the initial step in a software based Finite Element Analysis of any sophisticated structure associated with irregular shape, complex loading pattern and combination of different loads along with complex boundary condition. In the modelling of structure, Mesh Density plays a major role and it becomes a critical issue of finite element analysis, which closely relates to the accuracy of finite element model while directly determine their complexity level. This project report presents a systematic study on finding the effects of Mesh density on accuracy of numerical analysis results, based on which brief guidelines of choosing the best mesh strategy in finite element modelling is provided. In the project work, for studying the effect of Mesh Density, a bridge deck has been considered and analysis has been performed separately for Self-weight of the structure as well as Vehicular loading which is dynamic in nature. The modelling of the Bridge deck is performed several times with different mesh sizes for studying the analysis results to accomplish the best Mesh strategy that maintain the complexity level of the modelling without compromising in the accuracy of the analysis results. In addition, a case study on similar kinds of attempts to establish perfect Mesh size has been discussed briefly and a comparison has been made between the conclusions of this project work with the case study results, which are in line up to a great extent.

International Journal of Bridge Engineering, Vol. 6, No. 3, 2018: pp. 1-17

Biaxial Buckling of Thin Laminated Composite Plates

Osama Mohammed Elmardi Suleiman Khayal, Mahmoud Yassin Osman, Tagelsir Hassan

Abstract:Finite element (FE) method is presented for the analysis of thin rectangular laminated composite plates under the biaxial action of in – plane compressive loading, such plates are common on bridges. The analysis uses the classical laminated plate theory (CLPT) which does not account for shear deformations. In this theory it is assumed that the laminate is in a state of plane stress, the individual lamina is linearly elastic, and there is perfect bonding between layers. The classical laminated plate theory (CLPT), which is an extension of the classical plate theory (CPT) assumes that normal to the mid – surface before deformation remains straight and normal to the mid – surface after deformation. Therefore, this theory is only adequate for buckling analysis of thin laminates. A Fortran program has been compiled. New numerical results are generated for in – plane compressive biaxial buckling which serve to quantify the effects of lamination scheme, aspect ratio, material anisotropy, fiber orientation of layers, reversed lamination scheme and boundary conditions. It was found that symmetric laminates are stiffer than the anti – symmetric one due to coupling between bending and stretching which decreases the buckling loads of symmetric laminates. The buckling load increases with increasing aspect ratio, and decreases with increase in modulus ratio. The buckling load will remain the same even when the lamination order is reversed. The buckling load increases with the mode number but at different rates depending on the type of end support. It is also observed that as the mode number increases, the plate needs additional support.

International Journal of Bridge Engineering, Vol. 6, No. 3, 2018: pp. 19-44

Steel Bridges with Negative Sag under Concentrated or Distributed Moving Mass-Loads

Theodore G. Konstantakopoulos, George T. Michaltsos

Abstract:This work deals with the linear dynamic response of simply supported light (steel) bridges with negative sag under moving concentrated or distributed mass-loads of constant magnitude and velocity. The present analysis focuses on the determination of the influence limits of both the concentrated and the distributed mass-loads on the bridges’ vibration in relation to their velocity and to the sag magnitude of the bridge. The individual and coupling effect of these parameters on the dynamic response of the bridge are thoroughly discussed herein. A variety of numerical examples allow one to draw important conclusions for structural design purposes.

International Journal of Bridge Engineering, Vol. 6, No. 3, 2018: pp. 45-60

The Effect of Seismic Isolation on the Response of Bridges

Ali Vatanshenas, Davood Sharif Bajestany, Arian Aghelfard

Abstract:Precast concrete I girder and voided slab bridges are frequently used in many parts of the world. Therefore, understanding the seismic performance of these structures is important. The behavior of these structures during different strong ground motions were investigated in this study. Lead rubber bearings (LRB) were used to isolate these bridges from near-field earthquakes. The LRB isolator performed well in both bridges. It was observed that the performance of isolated bridges by LRB isolators were highly dependent on frequency contents of the earthquakes. In terms of deck displacement and deck acceleration there was no significant difference between the seismic responses of the considered structures under near-field earthquakes. It was shown that LRB isolator in voided slab bridge had to move and resist more compared to the precast concrete I girder bridge in order to absorb earthquake energy.

International Journal of Bridge Engineering, Vol. 6, No. 3, 2018: pp. 61-74

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