Grillage Analysis

2013 ◽  
pp. 129-130
Author(s):  
German Geotechnical Society
Keyword(s):  
Grillage Analysis

A Synthesis of Aluminum Crewboat Structural Design

1982 ◽  
Vol 19 (01) ◽  
pp. 52-72
Author(s):  
William A. Henrickson ◽  
John S. Spencer
Keyword(s):  
Structural Design ◽  
Beam Theory ◽  
Coast Guard ◽  
Observation Data ◽  
Plate Girders ◽  
Worked Example ◽  
Theory Versus ◽  
Grillage Analysis ◽  
Design Stress

The need exists for a simplified structural review guide to enable U.S. Coast Guard marine inspectors to verify the structural adequacy of aluminum crewboats. The authors have developed such a guide. Typical existing crewboat forms and service speeds have been used to reduce the determination of impact pressures to a function of length and displacement. A design stress limit for the cyclic loading of the bottom structure has been determined based on wave observation data. Plating design has been verified by a comparison of sizing by beam theory versus elastoplastic analysis. A simplified grillage analysis has been used to determine the level of support provided by longitudinal plate girders or keelsons. A worked example and tables of section moduli for typical extrusions attached to plating are included as appendices.

Three Dimensional Grillage Analysis of Reactions on Supports of a Pre-Erection Block

2013 ◽  
Author(s):  
Sungchan Kim ◽  
Cheolho Ryu ◽  
Youngho Kim ◽  
Changbong Han ◽  
Dong Geun Kim
Keyword(s):  
Load Distribution ◽  
Three Dimensional ◽  
Evaluation Process ◽  
Center Of Gravity ◽  
Integrated System ◽  
Structural Safety ◽  
Detail Design ◽  
Grillage Analysis ◽  
Cad Models ◽  
Reaction Forces

There are many PE(Pre-Erection) Blocks in open areas of the shipyard, which are supported by the wooden, concrete, or steel supports. Their position and numbers are decided on a basis of the workers’ experiences. Recently, many shipyards have been making PE blocks with various shape and weight distribution because of the variety of kinds of ships and their building technology. Seriously, they are treating blocks which have not been experienced. In order to evaluate the reliability of all support plans of PE Blocks in such situation, many man hours (MH) are consumed, and the special knowledge and technology about structural analysis are required. We proposed how to conveniently and quickly evaluate the structural safety on PE block supports and developed an application system to implement the evaluation process with three dimensional part models of the PE block and their weight information. The evaluation is based on the simplification to a grillage model of a PE block and its grillage analysis. The load distribution on the grillage model is calculated by two approaches. The first is that the load distribution on the grillage nodes are estimated with the real weight and the center of gravity of each part of a PE block, which can be provided from design databases of the shipyard. The other is that the load distribution is optimally estimated only with the weight and the center of gravity of sub blocks of a PE block. The latter is useful in the case that block information of mother ships can be obtained without the detail design of the PE block. The integrated system has been comprehensively implemented in order to make the grillage model from the three dimensional CAD models of the PE block and their weight information, and to perform the grillage analysis for the reaction forces on the block supports. In the application program, the grillage model can be automatically built from CAD models of PE block. Also the grillage can be modified by inserting, splitting, and deleting a beam element.

Effect of Poisson's ratio and beam spacing on grillage analysis of slab bridges

1988 ◽  
Vol 15 (5) ◽  
pp. 821-827
Author(s):  
Leslie G. Jaeger ◽  
Baidar Bakht
Keyword(s):  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Key Word ◽  
Grillage Analysis ◽  
Orthogonal Beams

It is now well established, strictly speaking, that a grillage composed solely of orthogonal beams can be used for the analysis of slab bridges only when the Poisson's ratio (v) of the slab material is taken to be zero. The effect on the various responses of using a grillage composed solely of orthogonal beams, and ignoring v, is discussed in this paper, and a method is given to account for the effect on transverse moments of making this simplifying assumption. The paper also contains procedures to determine the peak values of the various responses, as well as their integrated values over a given width of the bridge. Using these procedures, it is shown that the spacings of grillage beams in the conceptual grillages used for analysis do not influence the results as much as is generally believed. Key word: grillage analogy, longitudinal moment, Poisson's ratio, slab bridges, transverse moments.

Nonlinear analysis of grid systems

1989 ◽  
Vol 16 (3) ◽  
pp. 300-307
Author(s):  
Tharmalingham Tharmabala
Keyword(s):  
Nonlinear Analysis ◽  
Load Capacity ◽  
Numerical Procedure ◽  
Ultimate Load Capacity ◽  
Grid Systems ◽  
Girder Bridges ◽  
Stiffness Matrices ◽  
Grillage Analysis ◽  
Curvature And Torsion ◽  
Global Stiffness Matrix

A method is proposed for the nonlinear analysis of grid systems. The structure is loaded incrementally and the current stiffness matrices of each member are evaluated using a numerical procedure and the moment–curvature and torsion–twist relationships of the grid elements. The member stiffness matrices are used to develop the global stiffness matrix of the grid structure. In other respects, the method is very much similar to linear elastic analysis of grid framework. A bridge structure is analyzed using a computer program, developed by incorporating the proposed method. The program is able to predict the nonlinear characteristics of the structure such that it can reduce the girder moments and (or) the total material costs. Key words: bridges, nonlinear analysis, slab-on-girder bridges, grillage analysis, ultimate load capacity.

Plastic Grillage Analysis for Ship Structure Under Ice Loads

2009 ◽  
Author(s):  
S Liu ◽  
◽  
H Yu ◽  
R Basu ◽  
◽  
...  
Keyword(s):  
Ship Structure ◽  
Grillage Analysis ◽  
Ice Loads

Dealing with varying moments of inertia of girders in bridge analysis

1988 ◽  
Vol 15 (2) ◽  
pp. 232-239 ◽  
Author(s):  
Baidar Bakht ◽  
Leslie G. Jaeger
Keyword(s):  
Load Distribution ◽  
Moment Of Inertia ◽  
Moments Of Inertia ◽  
Finite Strip ◽  
Girder Bridges ◽  
Grillage Analysis ◽  
Computer Based ◽  
Manual Methods ◽  
The Moment

In many slab-on-girder bridges, especially those that are continuous over two or more spans, the moment of inertia of a girder varies significantly along the length of the bridge. This paper critically examines the practice of analyzing such bridges for load distribution by methods that make the assumption of constant longitudinal torsional and flexural rigidities. It is found that this practice may not be valid for those slab-on-girder bridges in which variations of the girder moments of inertia are very large.A recommended procedure is given for cases in which the variation in moment of inertia is not too severe. The procedure involves (a) the determination of total bending moments, treating the bridge as a beam of variable moment of inertia, and (b) the determination of an equivalent constant moment of inertia for beams of varying moment of inertia. Using this procedure the load distribution properties of the bridge can be realistically analyzed by those computer-based methods (e.g., orthotropic plate, finite strip, and semicontinuum methods) or manual methods (e.g., AASHTO and Ontario methods) that cannot directly take account of the variation of longitudinal flexural rigidity.The validity of the recommended procedure is established by comparing its results with those of the grillage analysis method that does take account of the variation of the girder moment of inertia. Key words: bridge analysis, girders, load distribution, slab-on-girder bridges.

Load distribution in edge stiffened slab and slab-on-girder bridge decks

1988 ◽  
Vol 15 (6) ◽  
pp. 977-983 ◽  
Author(s):  
K. N. Smith ◽  
I. Mikelsteins
Keyword(s):  
Load Distribution ◽  
Limit State ◽  
Bending Moment ◽  
Beam Deflection ◽  
Highway Bridge ◽  
Bridge Design ◽  
Grillage Analysis ◽  
Single Vehicle ◽  
Beam Bending ◽  
Girder Bridge

The results of a study on the effect of edge beam geometry on the static live-load load distribution characteristics of single-span slab and slab-on-girder bridge superstructures are presented. Using a grillage analysis, the influence of various forms of edge stiffening on longitudinal bending moment and vertical deflection at midspan was investigated. Two load cases utilizing the Ontario Highway Bridge Design truck were considered. Of particular interest is the load case of a single vehicle in a travelled lane, as edge beam deflection under this condition is governed by a serviceability limit state design requirement of the Ontario Highway Bridge Design Code.For the bridge geometry and loadings considered, all types of edge stiffening significantly affect edge beam bending moment and deflection at midspan; the effect generally increases as the span decreases. Edge beam bending moment increases as the stiffness of the edge beam is increased. Considering the change in edge beam stiffness, edge beam deflection decreases even though the bending moment carried by the edge beam increases. The results of the grillage analysis agree well with an interpretation of the simplified method of analysis of the Ontario Highway Bridge Design Code. When the deflection criterion is affecting a bridge design, it would be beneficial to account for the edge stiffening. Key words: load distribution, edge stiffening, edge beams, bridge deck analysis, grillage analysis.

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