Nonlinear Solution of Steel Arch Supports

2016 ◽  
Vol 713 ◽  
pp. 119-122 ◽  
Author(s):  
Lenka Koubova ◽  
Petr Janas ◽  
Martin Krejsa
Keyword(s):  
Cross Sections ◽  
Flexural Rigidity ◽  
Stress Test ◽  
Nonlinear Analyses ◽  
Structure Changes ◽  
Internal Forces ◽  
Direct Stiffness ◽  
Strain Stress ◽  
Nonlinear Solutions ◽  
Arch Supports

Steel arch supports are used widely in long workings in coal and ore mines. Their displacements are in difficult conditions often comparable with the size of the structure. Changes in the geometry of whole arch support including changes in the shape of a rod cross-section require geometric and physical nonlinear solutions. The paper is focused on methods for the geometric and physical nonlinear analyses of unyielding steel arch supports which are consisting of rolled open cross-sections. These methods are based on the knowledge of effective flexural rigidity which is defined as the function of acting internal forces. The direct stiffness method was used to solution first, but this method has some computational limitations. The modified force method was used for calculation as the second computational variant. This method can be successfully applied when the displacements are large. The results of the numerical analyses are compared with the values which have been experimentally obtained using strain-stress test of unyielding steel arch supports.

Bending tests for the structural safety assessment of space truss members

2018 ◽  
Vol 33 (3-4) ◽  
pp. 138-149 ◽  
Author(s):  
Marco Bonopera ◽  
Kuo-Chun Chang ◽  
Chun-Chung Chen ◽  
Tzu-Kang Lin ◽  
Nerio Tullini
Keyword(s):  
Cross Sections ◽  
Flexural Rigidity ◽  
Compressive Force ◽  
Scale Space ◽  
Transverse Load ◽  
Structural Safety ◽  
Small Scale ◽  
Order Effects ◽  
Beam Columns ◽  
Space Truss

This article compares two nondestructive static methods used for the axial load assessment in prismatic beam-columns of space trusses. Examples include the struts and ties or the tension chords and diagonal braces of steel pipe racks or roof trusses. The first method requires knowledge of the beam-column’s flexural rigidity under investigation, whereas the second requires knowledge of the corresponding Euler buckling load. In both procedures, short-term flexural displacements must be measured at the given cross sections along the beam-column under examination and subjected to an additional transverse load. The proposed methods were verified by numerical and laboratory tests on beams of a small-scale space truss prototype made from aluminum alloy and rigid connections. In general, if the higher second-order effects are induced during testing and the corresponding total displacements are accurately measured, it would be easy to obtain tensile and compressive force estimations.

Internal Forces and Steel Arrangement Analysis on the Steel Lined Reinforced Concrete Penstocks

2011 ◽  
Vol 94-96 ◽  
pp. 99-104
Author(s):  
Zhang Wei ◽  
Chuan Xiong Fu ◽  
Lu Feng Yang ◽  
Jin Zhang
Keyword(s):  
Reinforced Concrete ◽  
Axial Force ◽  
Cross Sections ◽  
Design Method ◽  
Internal Force ◽  
Concrete Wall ◽  
Inner Radius ◽  
Load Carrying ◽  
Internal Forces ◽  
Axisymmetric Structure

he steel lined reinforced concrete penstocks (SLRCP) is always looked as an axisymmetric structure according to the design code, which can not show the true load-carrying capacity when considering the dam’s constraint to the SLRCP. In this paper, the physical non-axisymmetric property of the structure is simulated using the finite element method. The internal force distribution of every cross section in the SLRCP is studied, and a design method for steel arrangement based on axial force is proposed. When considering the non-axisymmetric property, the axial force in those cross sections approaching the bottom of the structure may be reduced more than 30% to the calculated value by the axisymmetric analysis. The larger the inner radius of the penstock or the thickness of the concrete wall is, the more marked the non-axisymmetric property of the SLRCP is.

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.

scholarly journals Drooping of Gerbera flower heads: mechanical and structural studies of a well-known phenomenon

2019 ◽  
Vol 15 (9) ◽  
pp. 20190254 ◽  
Author(s):  
Laura-Sofie Lehmann ◽  
Tim Kampowski ◽  
Marco Caliaro ◽  
Thomas Speck ◽  
Olga Speck
Keyword(s):  
Cross Sections ◽  
Flexural Rigidity ◽  
Apical Part ◽  
Gerbera Jamesonii ◽  
Cut Flowers ◽  
Cross Sectional ◽  
Bending Tests ◽  
Cellular Solid ◽  
Second Moment ◽  
Three Point Bending

Gerbera , one of the most loved cut flowers, is (in)famous for the drooping of its flower heads under dehydration. This effect has been quantified by analysing both fully turgescent and wilting peduncles of Gerbera jamesonii ‘Nuance’. Wilting peduncles display pronounced bending in the region directly below the inflorescence after 24 h of dehydration, while the rest of the peduncle remains upright. Using anatomical measurements and three-point bending tests, we have analysed whether this phenomenon is caused by mechanical and/or geometrical alterations. We have found that both the flexural rigidity and the axial second moment of area are significantly decreased in the apical part of wilting peduncles, whereas the bending elastic modulus shows no significant change. Moreover, cross-sections of wilting peduncles ovalize significantly more than those of turgescent peduncles and exhibit considerable shrinkage of the parenchyma, taking up the majority of the cross-sectional area. Generally, the drooping of wilting Gerbera flowers can be regarded as a temporary instability of a rod-shaped cellular solid caused by anatomical differences (tissue arrangement, existence or the absence of a pith cavity) and geometrical changes (the decrease of axial second moment of area, cross-sectional ovalization, shrinkage of tissues) between the apical and basal regions of their peduncles.

scholarly journals Orientation effects of horizontal seismic components on longitudinal reinforcement in R/C frame elements

2012 ◽  
Vol 12 (1) ◽  
pp. 1-10 ◽  
Author(s):  
K. G. Kostinakis ◽  
A. M. Athanatopoulou ◽  
I. E. Avramidis
Keyword(s):  
Ground Motion ◽  
Cross Sections ◽  
Linear Response ◽  
Ground Motions ◽  
Longitudinal Reinforcement ◽  
Analysis And Design ◽  
History Analysis ◽  
Response History Analysis ◽  
Internal Forces ◽  
Horizontal Ground Motion

Abstract. The present paper investigates the influence of the orientation of recorded horizontal ground motion components on the longitudinal reinforcement of R/C frame elements within the context of linear response history analysis. For this purpose, three single-story buildings are analyzed and designed for 13 recorded bi-directional ground motions applied along the horizontal structural axes. The analysis and design is performed for several orientations of the recording angle of the horizontal seismic components. For each orientation the longitudinal reinforcement at all critical cross sections is calculated using four methods of selecting the set of internal forces needed to compute the required reinforcement. The results show that the reinforcement calculated by three of the applied methods is significantly affected by the orientation of the recording angle of ground motion, while the fourth one leads to results which are independent of the orientation of the recording angle.

Assessment of the plastic capacity of I-shaped cross-sections according to the partial internal forces method

2019 ◽  
Vol 191 ◽  
pp. 740-751 ◽  
Author(s):  
Rebekka Winkler ◽  
Rolf Kindmann ◽  
Markus Knobloch
Keyword(s):  
Cross Sections ◽  
Internal Forces

Numerical Analysis of a Rigid Node of a Spatial Timber Frame Made of Structural Elements with Built-up Cross-Sections

2013 ◽  
Vol 778 ◽  
pp. 639-646 ◽  
Author(s):  
Cristina E. Lanivschi ◽  
Alexandru Secu ◽  
Gabriela M. Atanasiu
Keyword(s):  
Numerical Analysis ◽  
Finite Elements ◽  
Elastic Properties ◽  
Design Process ◽  
Cross Sections ◽  
Structural Elements ◽  
Cross Sectional ◽  
Timber Frame ◽  
One Step ◽  
Internal Forces

Considering wood currently used in construction domain, it may be observed that it possesses good strengths, but reduced modules of elasticity. This drawback may be prevented by creating structures with rigid nodes or by using hybrid or composed cross-sections for the structural elements.The paper consists of numerical analysis of a timber frame with rigid nodes, assuming composed cross-sections for the structural elements, made of four props with cross-sectional dimensions of 0.1x0.1 m each - for columns and two chords of 0.1x0.1 m each - for beams.Analyzing this type of structures by considering equivalent cross sections` properties of the structural elements, the real phenomena may not be covered, since it doesn`t consider all elastic characteristics of wood, resulting in different stress` distribution in the structural elements.The analyze of this structure considering both real solid cross-sections and all elastic properties of wood by using specialized software, leads to a laborious work because of the high number of finite elements. Thereby, a two-step analysis is proposed: the first one consists in solving the spatial timber frame with bar type finite elements and the elastic properties parallel to the grain, as provided by design codes. In the second step, an intermediary node is detached and loaded with the internal forces obtained from the first step, considering all elastic parameters of wood and using solid type finite elements.Currently, in the design process, only the first step in performed. The two-step analysis aims to compare the results with those obtained using the strength of materials methods, relieving the necessary corrections in the case of one-step design process.

A 4-degree-of-freedom Kirchhoff beam model for the modeling of bending–torsion couplings in active-bending structures

2017 ◽  
Vol 32 (2) ◽  
pp. 69-83 ◽  
Author(s):  
Baptiste Lefevre ◽  
Frédéric Tayeb ◽  
Lionel du Peloux ◽  
Jean-François Caron
Keyword(s):  
Cross Sections ◽  
Beam Theory ◽  
Relaxation Method ◽  
Mathematical Work ◽  
Beam Model ◽  
Dynamic Relaxation ◽  
High Interaction ◽  
Slender Beams ◽  
Internal Forces ◽  
Dynamic Relaxation Method

Gridshells are lightweight structures made of interconnected slender beams. Due to large displacements, high interaction between the beams, and bending–torsion coupling, modeling gridshells requires specific non-linear numerical tools to reach convergence within a reasonable time. In this article, the development of such a tool is presented. It is based on the Kirchhoff beam theory and uses the dynamic relaxation method. First, from Kirchhoff’s equations, the internal forces and moments acting on a beam are obtained. Once this mathematical work is done, the dynamic relaxation method is used in order to get the static equilibrium configuration of the beam. This new approach is tested on several examples and validated for slender beams with arbitrary rest-state configuration and cross sections. In particular, results for ribbons with high bending–torsion coupling are presented. Finally, this process enables the fast and precise modeling of gridshells including bending–torsion coupling.

The Design Method of Major Parameters for Built-Up Columns

2014 ◽  
Vol 915-916 ◽  
pp. 264-272
Author(s):  
Gui Yu Lin ◽  
Yan Feng Luo ◽  
Ting Na Sun ◽  
Kui Xian Li
Keyword(s):  
Cross Sections ◽  
Critical Stress ◽  
Design Method ◽  
Geometrical Parameters ◽  
Preliminary Design ◽  
Working Stress ◽  
Support Force ◽  
Internal Forces ◽  
Independent Design ◽  
The Relationship

Built-up columns are widely used in engineering structure, but it is confusing for designers how to determine the parameters of built-up columns. The paper based on the user's basic needs which are the minimum working radius and working load, would simplify working load, support force and hoisting force to the vertex of built-up columns. From the origin of design, and to analyze mechanic behavior of built-up columns, and have found the relationship between internal forces, that is, the axial force, the swing force, the support force, and the working load. In accordance with design experience, the relationship between axial internal stress and its total working stress, critical stress and limit of yielding, had been respectively determined. According to this knowledge to determine the mass and the geometrical parameters of major cross-sections and roots of built-up columns, and a comparison between the results and ones of examples calculations were made, and it was found that the results are reasonable. This will offer a design method of determining the major parameters of built-up columns at the phase of the preliminary design, and improve the independent design capability.

Comments about the Seismic Behavior of “Inverted Y”- Braced Frames

2018 ◽  
Vol 763 ◽  
pp. 106-115
Author(s):  
Helmuth Köber ◽  
Marina Stoian
Keyword(s):  
Seismic Design ◽  
Cross Sections ◽  
Seismic Behavior ◽  
Braced Frames ◽  
Design Code ◽  
Nonlinear Analyses ◽  
Braced Frame ◽  
Seismic Design Code ◽  
Steel Consumption ◽  
Plastic Zones

Four configurations were analyzed for a ten storey “inverted Y-braced” frame with rigid and/or pined beam/column and diagonal/column connections. All considered frame configurations were sized for the forces produced by the same code seismic design force evaluated according to the in charge Romanian seismic design code. In case of two of the considered configurations, additional potentially plastic zones with reduced member cross-sections were provided along the girders and diagonals of the frame (in order to size clearly by design a global plastic failure mechanism for the “inverted Y-braced” frame). The behavior of each frame configuration during dynamic nonlinear analyses was observed. The steel consumption was estimated for each considered configuration.

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