Bridge deck analysis through the use of grillage models

International Journal for Research in Applied Science and Engineering Technology IJRASET, 2020

The majority of highway bridges are girder type structures, either single spans or continuous spans. Determining the principal effects of the various loading combinations can often be achieved with a 2-dimensional analytical model but for overall absolute analysis which is actually more complicated a 3-dimensional model is needed. This paper elaborates the correct analysis and modelling techniques for typical prestressed concrete bridge deck girder by using grillage analysis. The structural model is developed as per FE discretization in Staad Pro software. For the purpose of analysis, dead load (self-weight, wearing coat, super imposed dead load, footpath live load) and vehicular live loads are considered as per IRC: 6-2016. A series of applications are executed in order to verify the efficiency and the accuracy. Linear static analysis is carried and the design values of bending moment and shear force for the class A 70 R tracked vehicle are computed.

The simplest form of bridge is the single-span beam or slab which is simply supported at its ends. Many methods are used in analyzing bridges such as grillage and finite element methods. Since its publication in 1976 up to the present day, Edmund Hambly's book " Bridge Deck Behaviors " has remained a valuable reference for bridge engineers. During this period the processing power and storage capacity of computers has increased by a factor of over 1000 and analysis software has improved greatly in sophistication and ease of use. In spite of the increase in computing power, bridge deck analysis methods have not changed to the same extent, and grillage analysis remains the standard procedure for most bridges deck. The grillage analogy method for analyzing bridge superstructures has been in use for quite some time. An attempt is made in this paper to provide guidance on grillage idealization of the structure, together with the relevant background information. Guidance is provided on the mesh layout. The bridge deck is analyzed by both grillage analogy as well as by finite element method. Bridge deck analysis by grillage method is also compared for normal meshing, coarse meshing and fine meshing. Though finite element method gives lesser values for bending moment in deck as compared to grillage analysis, the later method seems to be easy to use and comprehend.

Tehnicki Vjesnik, 2012

Original scientific paper In this paper the deflections determined from short term static load testing on the approach viaducts of the bridge over the river Sava in Brod are used to evaluate different numerical grillage models. The approach viaduct decks are made up as partial-precast ribbed deck continuous over piers by casting a continuous concrete diaphragm between the ends of adjoining longitudinal girders. In practical calculations the longitudinal members are assumed to be fully continuous for traffic and composite loads using constant sectional properties along the longitudinal members although this assumption is not entirely correct. The aim of this paper is the verification and improvement of the grillage model of the concrete approach viaduct of the bridge over the river Sava in Brod utilizing field testing and numerical grillage analysis.

COMPARATIVE STUDY OF DIFFERENT MODELING TECHNIQUES OF BOX-GIRDER BRIDGE DECK, 2005

In this paper, the analysis of one-cell-box-girder deck using two of the most common computer modeling techniques is introduced. These methods are: (a) grillage analysis method and (b) beam analysis method. The results of these different methods are compared to the results of a loading test on a real bridge. A parametric study is also introduced to study the effect of many parameters on the structural behavior of this kind of bridge decks.

Paper submitted to Eng. & Technology …

The analysis principle was used to analyze anisotropic plates (having different elastic properties and geometries in different directions), the model consist of four side beams with flexural rigidity and torsional rigidity and two diagonal beams with only flexural rigidity. The substitute grid framework is analyzed to give the same deformations and deflections of the orthotropic plate element of the modeled bridge. Applicability of the suggested procedure in the analysis of actual bridge decks is investigated using STAAD Pro.2006program. The results show that the suggested procedure is an acceptable procedure which can be adopted to analyze this type of bridge deck. It is found that the modified grillage method gives simpler method and adequate results when compared with the Finite Element Method or orthotropic plate theory solved using Finite Difference Method for this type of bridges.

PARAMETRIC STUDY OF THE STRUCTURAL BEHAVIOR OF HORIZONTALLY CURVED BRIDGE DECK, 2016

This paper investigates the impact of the following parameters on the structural behavior of horizontally curved bridge decks: A-The analytical modeling method, B-The radius of curvature, C-The number of internal cross girders, and D-The thickness of deck slab. The results of the different analytical modeling technique are compared to experimental results by conducting a load test on a physical model at the structural lab of the American University in Cairo cairo as a part of a research for curved bridges directed by the author.The remaining parameters of this study are investigated using a typical curved bridge deck commonly used in real projects. The impact of these parameters is addressed by the change in straining actions and the deflection of the main girders of the bridges.

The simplest form of bridge is the single-span beam or slab which is simply supported at its ends. Many methods are used in analyzing bridges such as grillage and finite element methods. Since its publication in 1976 up to the present day, Edmund Hambly's book "Bridge Deck Behaviors" has remained a valuable reference for bridge engineers. During this period the processing power and storage capacity of computers has increased by a factor of over 1000 and analysis software has improved greatly in sophistication and ease of use. In spite of the increase in computing power, bridge deck analysis methods have not changed to the same extent, and grillage analysis remains the standard procedure for most bridges deck. The grillage analogy method for analyzing bridge superstructures has been in use for quite some time. An attempt is made in this paper to provide guidance on grillage idealization of the structure, together with the relevant background information. Guidance is provided on the mesh layout. The bridge deck is analyzed by both grillage analogy as well as by finite element method. Bridge deck analysis by grillage method is also compared for normal meshing, coarse meshing and fine meshing. Though finite element method gives lesser values for bending moment in deck as compared to grillage analysis, the later method seems to be easy to use and comprehend.

2019

Grillage analogy presents a sufficiently accurate method of analyzing bridge decks for estimation of design bending moment, torsion shear force etc, and has been adapted for use in most computer software around the world. Basically, analogy method uses stiffness approach for analyzing the bridge deck is divided into a number of longitudinal and transverse beams. In this paper a study is conducted on different spans of Grid Slab Bridge. A general purpose program has been developed in Visual Basic environment by combining the methodologies. The program was validated with results of standard software available for the intended purpose. The results obtained from the program are plotted for comparison and the conclusions are drawn.

U.Porto Journal of Engineering

This study involves the applicability of a simplified modeling technique to simple-span slab-girder skewed bridges for dynamic analysis, based on grillage modeling strategies. To evaluate the applicability of this technique, skew angles ranging from 0° to 60° are studied. The ability to capture vibration modes of grillage models is compared with three-dimensional (3-D) finite element (FE) models, using shell and frame elements. The effect of the skew angle in the grillage modeling technique of the bridge's deck and the grillage model accuracy associated with the orientation of the transverse grillage members (TGMs) are studied. The grillage modeling technique eliminates shell elements to model the slab, reducing the number of degrees of freedom and the computational time in the bridge model, but, although its simplicity, demonstrates good ability to capture the vibration modes.