The grillage analogy in bridge analysis

1982 ◽  
Vol 9 (2) ◽  
pp. 224-235 ◽  
Author(s):  
Leslie G. Jaeger ◽  
Baidar Bakht
Keyword(s):  
Flexural Rigidity ◽  
Torsional Rigidity ◽  
Cellular Structures ◽  
Background Information ◽  
Analogy Method ◽  
Bridge Superstructures ◽  
Varying Thickness ◽  
Mesh Layout ◽  
Made In

The grillage analogy method for analyzing bridge superstructures has been in use for quite some time. The idealization of a bridge by a grillage is not axiomatic and is not without pitfalls. An attempt is made in this paper to provide guidance on grillage idealization of various types of structure, together with the relevant background information. Specifically, the paper deals with the idealization of slab, beam-and-slab, cellular, and voided-slab bridges. Idealization of slabs of linearly varying thickness is also discussed. Guidance is provided on the mesh layout. Keywords: analysis, beam-and-slab bridges, cellular structures, flexural rigidity, grillage, idealization, load, mesh, slab bridges, torsional rigidity, voided slab.

Progress and Prospects for the Development of Computer-Generated Actors for Military Simulation: Part 1-Introduction and Background

2003 ◽  
Vol 12 (3) ◽  
pp. 311-325 ◽  
Author(s):  
Martin R. Stytz ◽  
Sheila B. Banks
Keyword(s):  
Research Area ◽  
Background Information ◽  
Life Cycle Costs ◽  
Material Management ◽  
Reasoning System ◽  
Force Structure ◽  
The Cost ◽  
Future Work ◽  
Level Training ◽  
Made In

The development of computer-generated synthetic environments, also calleddistributed virtual environments, for military simulation relies heavily upon computer-generated actors (CGAs) to provide accurate behaviors at reasonable cost so that the synthetic environments are useful, affordable, complex, and realistic. Unfortunately, the pace of synthetic environment development and the level of desired CGA performance continue to rise at a much faster rate than CGA capability improvements. This insatiable demand for realism in CGAs for synthetic environments arises from the growing understanding of the significant role that modeling and simulation can play in a variety of venues. These uses include training, analysis, procurement decisions, mission rehearsal, doctrine development, force-level and task-level training, information assurance, cyberwarfare, force structure analysis, sustainability analysis, life cycle costs analysis, material management, infrastructure analysis, and many others. In these and other uses of military synthetic environments, computer-generated actors play a central role because they have the potential to increase the realism of the environment while also reducing the cost of operating the environment. The progress made in addressing the technical challenges that must be overcome to realize effective and realistic CGAs for military simulation environments and the technical areas that should be the focus of future work are the subject of this series of papers, which survey the technologies and progress made in the construction and use of CGAs. In this, the first installment in the series of three papers, we introduce the topic of computer-generated actors and issues related to their performance and fidelity and other background information for this research area as related to military simulation. We also discuss CGA reasoning system techniques and architectures.

Praise in Gifted Education: Analyses on the Basis of the Actiotope Model of Giftednesss

2005 ◽  
Vol 20 (3) ◽  
pp. 306-329 ◽  
Author(s):  
Heidrun Stoeger ◽  
Albert Ziegler
Keyword(s):  
Gifted Education ◽  
Theoretical Background ◽  
Background Information ◽  
Practical Advice ◽  
Excellent Opportunity ◽  
Alternative Theories ◽  
Made In

In contrast to alternative theories of giftedness, the Actiotope Model of Giftedness focuses on actions. Praise presents an excellent opportunity to encourage and reinforce the appearance of new or more effective actions. However, several investigations have shown that, in practice, the opportunities which arise to grant praise are not fully taken advantage of, and that praise is often given in inappropriate, dysfunctional manners. Frequent consequences of this are detrimental influences on the development of gifted individuals. In this contribution we will first, on the basis of the Actiotope Model of Giftedness, offer theoretical background information pertaining to the praise of gifted individuals. Afterward, practical advice will be proposed, and the most frequent errors made in the practice of praise will be addressed in conjunction with alternative actions.

Influence of the Torsional Rigidity of Transverse Stiffeners upon the Shear Buckling of Stiffened Plates

1964 ◽  
Vol 15 (2) ◽  
pp. 198-202 ◽  
Author(s):  
K. C. Rockey ◽  
I. T. Cook
Keyword(s):  
Flexural Rigidity ◽  
Torsional Rigidity ◽  
Stiffened Plates ◽  
Simply Supported ◽  
Rigidity Results ◽  
Buckling Resistance ◽  
Shear Buckling

SummaryThe paper provides relationships between the buckling resistance of simply-supported transversely stiffened plates and the flexural rigidity of the stiffeners for various values of the ratio of torsional rigidity to nexural rigidity. Results are presented for four different stiffener spacings.

Active Use of Analogy Method With Technology in Education

2020 ◽  
pp. 69-82
Author(s):  
Melike Çetinkaya
Keyword(s):  
Technology In Education ◽  
Educational Method ◽  
Analogy Method ◽  
Human Thought ◽  
Made In

The aim of this study is to reveal the analogy, which is an essential part of human thought in comprehending and comprehending concepts, and also an educational method compiled from the studies made in the literature. Analogies are a type of model, and their main purpose is to simplify and thus help us focus on the attributes of a particular part or a specific feature. In this chapter, the analogy method as an educational method is discussed in detail, the types of analogy, the issues to be considered in use and the development in technology, and the active use of the analogy method with technology are explained.

Background of the Half-Pipe Jacket Rules in Section VIII, Division 1

1994 ◽  
Vol 116 (3) ◽  
pp. 336-338
Author(s):  
M. H. Jawad
Keyword(s):  
Background Information ◽  
Division 1 ◽  
Section Viii ◽  
Made In

New rules for the design of half-pipe jackets were developed by the ASME Subgroup on Design of Section VIII. This article gives the background information for the derivation and various assumptions made in developing the rules.

Shear Buckling of Clamped and Simply-Supported Infinitely Long Plates Reinforced by Closed-Section Transverse Stiffeners

1962 ◽  
Vol 13 (3) ◽  
pp. 212-222 ◽  
Author(s):  
I. T. Cook ◽  
K. C. Rockey
Keyword(s):  
Circular Tube ◽  
Flexural Rigidity ◽  
Torsional Rigidity ◽  
Numerical Results ◽  
Rectangular Plates ◽  
Simply Supported ◽  
Shear Buckling ◽  
Thin Walled ◽  
The Individual

SummaryThe paper presents a solution to the buckling of infinitely long plates when they are reinforced by transverse stiffeners possessing both torsional and flexural rigidity. The cases of both edges being clamped and simply-supported are dealt with. Numerical results are presented for the ratio of torsional rigidity to flexural rigidity as obtained with a thin-walled circular tube. When the stiffeners are completely rigid, in which case the individual panels are clamped along the transverse edges, the results obtained are in agreement with existing solutions for isolated rectangular plates.

Wrinkling of an Unevenly Stretched Sheet Metal

1989 ◽  
Vol 111 (3) ◽  
pp. 235-242 ◽  
Author(s):  
Xiaofang Wang ◽  
L. H. N. Lee
Keyword(s):  
Finite Element Method ◽  
Sheet Metal ◽  
Strong Influence ◽  
Flexural Rigidity ◽  
Plastic Material ◽  
Yield Function ◽  
Material Parameters ◽  
Varying Thickness ◽  
Anisotropic Yield Function ◽  
Elastic Plastic Material

The onset of wrinkling of an unevenly stretched sheet metal subject to finite deformation is analyzed by an incremental finite element method. The sheet metal is modeled as a plate made of an elastic-plastic material. Hill’s anisotropic yield function and bifurcation criterion are employed in the analysis. The effects of geometrical and material parameters upon the onset of wrinkling are investigated. In the bifurcation analysis, attention is given to the changing and varying thickness of the sheet metal which could have a strong influence on the flexural rigidity of the sheet. Numerical results are presented herein.

scholarly journals Twist-to-Bend Ratios and Safety Factors of Petioles Having Various Geometries, Sizes and Shapes

2021 ◽  
Vol 12 ◽  
Author(s):  
Max Langer ◽  
Mark C. Kelbel ◽  
Thomas Speck ◽  
Claas Müller ◽  
Olga Speck
Keyword(s):  
Safety Factor ◽  
Flexural Rigidity ◽  
Load Capacity ◽  
Torsional Rigidity ◽  
Maximum Load ◽  
High Twist ◽  
Safety Factors ◽  
Bending Tests ◽  
3 Dimensional ◽  
Spatial Configurations

From a mechanical viewpoint, petioles of foliage leaves are subject to contradictory mechanical requirements. High flexural rigidity guarantees support of the lamina and low torsional rigidity ensures streamlining of the leaves in wind. This mechanical trade-off between flexural and torsional rigidity is described by the twist-to-bend ratio. The safety factor describes the maximum load capacity. We selected four herbaceous species with different body plans (monocotyledonous, dicotyledonous) and spatial configurations of petiole and lamina (2-dimensional, 3-dimensional) and carried out morphological-anatomical studies, two-point bending tests and torsional tests on the petioles to analyze the influence of geometry, size and shape on their twist-to-bend ratio and safety factor. The monocotyledons studied had significantly higher twist-to-bend ratios (23.7 and 39.2) than the dicotyledons (11.5 and 13.3). High twist-to-bend ratios can be geometry-based, which is true for the U-profile of Hosta x tardiana with a ratio of axial second moment of area to torsion constant of over 1.0. High twist-to-bend ratios can also be material-based, as found for the petioles of Caladium bicolor with a ratio of bending elastic modulus and torsional modulus of 64. The safety factors range between 1.7 and 2.9, meaning that each petiole can support about double to triple the leaf’s weight.

scholarly journals Twist-to-bend ratio: an important selective factor for many rod-shaped biological structures

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Steve Wolff-Vorbeck ◽  
Max Langer ◽  
Olga Speck ◽  
Thomas Speck ◽  
Patrick Dondl
Keyword(s):  
Cross Sections ◽  
Phase Field ◽  
Material Properties ◽  
Flexural Rigidity ◽  
Torsional Rigidity ◽  
Cross Sectional ◽  
Deep Groove ◽  
Biological Structures ◽  
The Cross ◽  
Sectional Shape

AbstractMechanical optimisation plays a key role in living beings either as an immediate response of individuals or as an evolutionary adaptation of populations to changing environmental conditions. Since biological structures are the result of multifunctional evolutionary constraints, the dimensionless twist-to-bend ratio is particularly meaningful because it provides information about the ratio of flexural rigidity to torsional rigidity determined by both material properties (bending and shear modulus) and morphometric parameters (axial and polar second moment of area). The determination of the mutual contributions of material properties and structural arrangements (geometry) or their ontogenetic alteration to the overall mechanical functionality of biological structures is difficult. Numerical methods in the form of gradient flows of phase field functionals offer a means of addressing this question and of analysing the influence of the cross-sectional shape of the main load-bearing structures on the mechanical functionality. Three phase field simulations were carried out showing good agreement with the cross-sections found in selected plants: (i) U-shaped cross-sections comparable with those of Musa sp. petioles, (ii) star-shaped cross-sections with deep grooves as can be found in the lianoid wood of Condylocarpon guianense stems, and (iii) flat elliptic cross-sections with one deep groove comparable with the cross-sections of the climbing ribbon-shaped stems of Bauhinia guianensis.

Shear Buckling of Orthogonally Stiffened, Infinitely Long Simply-Supported Plates–Stiffeners having Torsional and Flexural Rigidities

1969 ◽  
Vol 20 (1) ◽  
pp. 75-87
Author(s):  
K. C. Rockey ◽  
I. T. Cook
Keyword(s):  
Cross Section ◽  
Flexural Rigidity ◽  
Torsional Rigidity ◽  
List Type ◽  
Rectangular Plates ◽  
Simply Supported ◽  
Longitudinal Stiffener ◽  
Rigidity Parameter ◽  
Longitudinal Stiffeners ◽  
Shear Buckling

SummaryThe paper presents a solution to the buckling under shear stress of infinitely long plates orthogonally reinforced by stiffeners having both flexural and torsional rigidity. Each family of stiffeners is assumed to consist of equally spaced identical stiffeners. Numerical results are given for the case of a plate with transverse stiffeners and a central longitudinal stiffener for the following three cases: (i)Transverse and longitudinal stiffeners of closed tubular cross-section.(ii)Transverse stiffeners of closed tubular cross-section, longitudinal stiffeners possessing only flexural rigidity.(iii)Transverse stiffeners possessing only flexural rigidity, the longitudinal stiffeners being of closed tubular cross-section.Relationships between the buckling stress parameter K and the flexural rigidity parameter γ of the stiffeners are presented for each of the three cases when the identical transverse stiffeners are placed at spacings of d, 0·8d and 0·5d, where d is the depth of the webplate.Case (i) has provided values of the buckling coefficient K for finite rectangular plates clamped on three edges and simply-supported on the remaining edge.

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