scholarly journals TO QUESTION OF COMBINED SYSTEMS RATIONALIZATION

2019 ◽  
pp. 97-103
Author(s):  
S. D. SINCHUK
Keyword(s):  
Cross Sections ◽  
Bending Moment ◽  
Variable Number ◽  
Bending Moments ◽  
New Approach ◽  
Present Solution ◽  
Combined Structure ◽  
Optimal Values ◽  
The Cross ◽  
Effective Design

Purpose. Developing a new approach to the rationalization of the combined structure, taking into account constructive, technological, operational and economic requirements. Methodology. The bending moment adjustment method representations to achieve the goal, based on the properties of the thrust-systems, namely: in the combination beam construction cost material defining elements are experiencing stress state of compression with a bend; in cells operating at the bending compression, reducing the size of the cross section largely determined by the decrease of the bending moment; bending moments increase from the support to the middle of the span. Originality. On the basis of calculations using the methodology set forth above, the algorithm of optimal design of truss beams under the influence of permanent and temporary load. The present solution allows to obtain an effective design combined with a variable number of racks, depending on the required span length, corresponding to the received optimality criterion. Practical value. The use of this approach and the optimization algorithm based on the use of the design features of truss beams and requires minimization of bending moments, will significantly reduce the complexity of the calculation, as well as to find the optimal values of the cross sections for each case.

scholarly journals Premature destruction of two-span RC beams exposed to high temperature caused by a redistribution of shear forces

2016 ◽  
Vol 23 (4) ◽  
pp. 431-439 ◽  
Author(s):  
Robert KOWALSKI ◽  
Michał GŁOWACKI ◽  
Marian ABRAMOWICZ
Keyword(s):  
High Temperature ◽  
Cross Sections ◽  
Bending Moment ◽  
Middle Part ◽  
Transverse Reinforcement ◽  
Shear Load ◽  
Bending Moments ◽  
Rc Beams ◽  
Shear Forces ◽  
Load Bearing Capacity

When multi-span RC elements are exposed to fire one usually observes a yielding of span cross-sections while a safety reserve of support cross-sections is still significant. Due to this phenomenon a redistribution of bending moments occurs and the values of sagging moment in span cross-sections decrease while the values of hogging moment in support cross-sections increase. This paper shows the results of tests conducted on two-span RC beams in a situation when only one span has been exposed to high temperature from the bottom. The beams were 12×16 cm in their cross-section. The length of the span was 165 cm. The load has been applied by two forces put on each span. The beams were made of C25/30 concrete with siliceous aggregate. As a result of significant stiffness decrease of the heated span, redistribution of shear forces and bending moment occurs. Due to this redistribution the tested beams were prematurely damaged due to exhaust of the shear load bearing capacity in the middle part of the beam span where there was no transverse reinforcement.

scholarly journals FE Analyses of Hyperelastic Solids under Large Bending: The Role of the Searle Parameter and Eulerian Slenderness

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1597
Author(s):  
Federico Oyedeji Falope ◽  
Luca Lanzoni ◽  
Angelo Marcello Tarantino
Keyword(s):  
Theoretical Model ◽  
Cross Sections ◽  
Finite Elasticity ◽  
Bending Moment ◽  
Longitudinal Axis ◽  
Theoretical Formulation ◽  
The Cross ◽  
Finite Bending ◽  
Compactness Index

A theoretical model concerning the finite bending of a prismatic hyperelastic solid has been recently proposed. Such a model provides the 3D kinematics and the stress field, taking into account the anticlastic effects arising in the transverse cross sections also. That model has been used later to extend the Elastica in the framework of finite elasticity. In the present work, Finite Element (FE) analyses of some basic structural systems subjected to finite bending have been carried out and the results have been compared with those provided by the theoretical model performed previously. In the theoretical formulation, the governing equation is the nonlinear local relationship between the bending moment and the curvature of the longitudinal axis of the bent beam. Such a relation has been provided in dimensionless form as a function of the Mooney–Rivlin constitutive constants and two kinematic dimensionless parameters termed Eulerian slenderness and compactness index of the cross section. Such parameters take relevance as they are involved in the well-known Searle parameter for bent solids. Two significant study cases have been investigated in detail. The results point out that the theoretical model leads to reliable results provided that the Eulerian slenderness and the compactness index of the cross sections do not exceed fixed threshold values.

scholarly journals Proposal of new expressions for the calculation of section factor on structural steel columns in contact with walls

Fire Research ◽  
2019 ◽  
Vol 3 (1) ◽  
Author(s):  
António Correia ◽  
Paula Lopes ◽  
João Rodrigues ◽  
José Correia
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Numerical Models ◽  
Favorable Effect ◽  
Thermal Gradients ◽  
New Approach ◽  
Steel Columns ◽  
Eurocode 3 ◽  
The Cross ◽  
In Fire

The fire resistance of a steel column is highly affected by the contact between the columns and the walls, leading in general to a favorable effect due to the reduction of temperatures. However, it leads to the Thermal Bowing effect, which is not more than a differential heating in the steel cross sections, causing an inversion of bending moments and an inversion of the deflections of the column. Thus, it is necessary to accurately assess the evolution of the temperature field in the cross section of the steel elements in contact with walls. In Eurocode 3 part 1-2, the structural design of steel elements in fire situation is performed with expressions for the calculation of the section factor of steel profiles, but different cases of positioning the columns and the surrounding walls could be considered as causing extremely high thermal gradients. In this paper, a new approach for the calculation of section factors for cases not included in table 4.2 of Eurocode 3, part 1- 2 are presented. This was achieved using numerical models with finite element modelling with the ABAQUS program, varying the cross-section of the columns, orientation of the web in relation to the walls, and the position and thickness of the walls, to achieve the desired section factors.

Predicted Response of the Die-Carrier Assembly in Flexible Electronics to the Combined Action of Tension and Bending Applied to the Carrier

2011 ◽  
Vol 79 (1) ◽  
Author(s):  
E. Suhir
Keyword(s):  
Mathematical Model ◽  
Normal Stress ◽  
Cross Sections ◽  
Flexible Electronics ◽  
Bending Moments ◽  
Analysis And Design ◽  
Tensile Forces ◽  
Combined Action ◽  
The Cross

A die-carrier assembly, subjected to the external tensile forces and bending moments applied to the flexible carrier is considered. The objective of the analysis is to develop a simple, easy-to-use, and physically meaningful predictive analytical (“mathematical”) model aimed at understanding the physics of the combined action of tension and bending experienced by the carrier and transmitted to the die through the more-or-less compliant bond. The addressed stresses include the interfacial shearing and peeling stresses, as well as the normal stress acting in the cross sections of the die. The obtained formulae can be used in the analysis and design of assemblies of the type in question.

REGULATION OF GUYED MAST STRESSES

2009 ◽  
Vol 1 (2) ◽  
pp. 65-72 ◽  
Author(s):  
Donatas Jatulis ◽  
Algirdas Juozapaitis
Keyword(s):  
Numerical Experiment ◽  
Cross Section ◽  
Cross Sections ◽  
Mobile Communications ◽  
Bending Moment ◽  
Physical Parameters ◽  
Bending Moments ◽  
Rational Distribution ◽  
Guyed Mast ◽  
Prestressed Structures

Development of mobile communications and their networks in Lithuania produced an essential influence on high telecommunications structures design activities. In its turn it has stimulates their research and innovations of such structural systems. One of the most efficient systems of telecommunication structures is guyed mast. It should be indicated that the behaviour of prestressed structures systems has been thoroughly examined in many investigations. But recently the increase of economical efficiency of guyed masts becomes undoubtedly actual. The development of such structures in many cases is directed to the selection in the mast elements scheme and their cross-sections. It should be underlined that geometric and physical parameters have a decisive moment on prestressed structures. An exact parameters choice allows to obtain in the mast rational distribution of bending moments, predetermining a project solution closely connected with the mass criteria. The diagram of bending moment’s distribution in guyed mast is considered rational when negative and positive moment values are absolutely equal. In the present research, analytical expressions for rational bending moments determining are presented. Above mentioned non-linear expressions estimate an influence of axial force for the bending moments. When solving the task of rational bending moments in a guyed mast, it is necessary to select suitable (i.e. rational) guyed mast bending spans. In the article is described the calculations of the guys fastening altitudes when guy level number is known. It should be noted that it is necessary to use the way of gradual approximation. The sequence of calculations is interrupted, when the sum of guyed mast spans corresponds to the exactness selected. The decisive part in mast behaviour is played by guys. The main parameters of them are pretension and cross-section area. In the article the equations are presented for determining the above-mentioned parameters. It should be stressed that after making uniform stresses of the guys on the different level of each of them it is possible to minimise some steel quantities. In the article a numerical experiment is presented for determining the technical-economical effectiveness of stress regulation. For the analysis, a standard three edged lattice guyed mast with cross-section parameters was selected in a usual way. By the suggested beam composition methods the design of the shaft was performed, and the results obtained were compared to a standard guyed mast shaft. For determining the stresses of beam elements Robot Millennium software was used; its reliability was demonstrated by earlier investigations. The results of numerical experiment that the maximal bending moment of composed guyed mast is three times less than that of a standard maximal one. An applied regulation of stresses has allowed to lessen much of the cross-section of guy rope. By applying the suggested methods it was possible to diminish the steel expenditure of shaft by more than 30%.

Combined Bending and Compression of a Pressurized Circular Cylindrical Membrane Column

1965 ◽  
Vol 87 (3) ◽  
pp. 372-378
Author(s):  
W. E. Jahsman
Keyword(s):  
Compressive Strength ◽  
Cross Section ◽  
Compressive Load ◽  
Circular Cross Section ◽  
Bending Moment ◽  
Maximum Load ◽  
Bending Moments ◽  
Lateral Deflection ◽  
The Cross

Load-lateral deflection curves are developed for a pressurized tube of circular cross section under combined bending and compression. The tube walls are assumed to have negligible compressive strength so that wrinkling develops if the stress tends to become negative. It is found that for a given bending moment, the load increases monotonically with deflection until a maximum is reached beyond which the load decreases with increasing deflection. An interaction curve of the maximum load versus bending moment shows that the presence of only a small amount of bending significantly decreases the maximum compressive load below the classical Euler load. Conversely, for bending moments which produce almost complete wrinkling of the cross section, only very small amounts of compressive load can be supported.

scholarly journals Bending Resistance of Composite Sections with Nonductile Shear Connectors and Partial Shear Connection

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Svetlana M. Kostic ◽  
Biljana Deretic-Stojanovic
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Bending Moment ◽  
Nonlinear Material ◽  
Parameter Study ◽  
Shear Connectors ◽  
Shear Connection ◽  
The Cross ◽  
Section Analysis ◽  
Composite Steel

The paper presents the nonlinear section analysis for composite steel-concrete beams with different degrees of shear connection. The analysis is fiber based, i.e., integration over the cross section is performed numerically, and any uniaxial nonlinear material model can be assigned to the steel and concrete parts of the cross section or to the reinforcement bars. The analysis assumed full interaction between steel and concrete and therefore, is suitable for analysis of composite steel-concrete beam cross sections with nonductile shear connectors. Its accuracy is verified on few experimental results. The presented section analysis is used in the parameter study in order to evaluate different methods proposed by design codes for determining the bending moment resistance of composite cross sections with nonductile shear connectors and different degrees of shear connection. The following effects are considered: variation of concrete and steel material models, presence of slab reinforcement, and creep of concrete. Special attention is paid on two different constructional methods: propped and unpropped. The weaknesses of the simplified design method in determining bending moment resistance are identified and recommendations for practical design analysis are formulated.

A New Approach to Analyzing Reactions and Deflections of Beams: Formulation and Examples

2006 ◽  
Author(s):  
I. C. Jong ◽  
J. J. Rencis ◽  
H. T. Grandin
Keyword(s):  
Boundary Conditions ◽  
Shear Force ◽  
Flexural Rigidity ◽  
Bending Moment ◽  
Bending Moments ◽  
Shear Forces ◽  
Concentrated Force ◽  
New Approach ◽  
Concentrated Forces ◽  
The Right

This paper is aimed at developing a new approach to analyzing statically indeterminate reactions at supports, as well as the slopes and deflections, of beams. The approach uses a set of four general formulas, derived using singularity functions. These formulas are expressed in terms of shear forces, bending moments, distributed loads, slopes, and deflections of a beam having a constant flexural rigidity and carrying typical loads. These loads include (a) a bending moment and a shear force at the left, as well as at the right, end of the beam; (b) a concentrated force, as well as a concentrated moment, somewhere on the beam; and (c) a uniformly, as well as a linearly varying, distributed force over a portion of the beam. The approach allows one to treat reactions at supports (even supports not at the ends of a beam) as concentrated forces or moments, where corresponding boundary conditions at the points of supports are to be imposed. This feature allows one to readily determine reactions at supports as well as slopes and deflections of beams. A beam needs to be divided into segments for study if it contains discontinuities in slope at hinge connections or different flexural rigidities in different segments. Several examples are included to illustrate the new approach.

A New Approach to Determining the Bending Moment in Tube Forming

2015 ◽  
Vol 1127 ◽  
pp. 31-37
Author(s):  
Eva Peterková ◽  
Radko Samek
Keyword(s):  
Cross Section ◽  
Bending Moment ◽  
Material Model ◽  
Bending Moments ◽  
Rigid Plastic ◽  
Hardening Material ◽  
New Approach ◽  
The Real ◽  
Tube Cross Section ◽  
Subsequent Integration

The article deals with more precise method of bending moment determination for rigid plastic work hardening material. Unlike earlier methods, a new methodology takes into account the real shape of the deformed tube cross-section after bending. The real centroid position of the tube cross-section, the change of wall thickness and the irregularly deformed tube cross-section are considered. The paper presents a possible way of determining the real bending moment, reflecting the geometrical changes of the “flattened” cross-section. This approach is based on the subsequent integration of elementary bending moments, which reflects successive changes of the bending stress and a material model as well.

scholarly journals Optimization of the parameters of truss beams with two posts

2021 ◽  
Vol 48 (3) ◽  
pp. 117-132
Author(s):  
A. K. Yusupov ◽  
H. M. Musеlеmov, ◽  
T. O. Ustarhanov
Keyword(s):  
Cross Section ◽  
Optimal Parameter ◽  
Bending Moment ◽  
Internal Force ◽  
Numerical Calculations ◽  
Design Parameters ◽  
Bending Moments ◽  
The Cross ◽  
Theoretical Results

Based on the theoretical results obtained in the article [17], here the analysis of the influence of various design parameters on the own weight and cost of metal of truss beams with two posts is carried out. An optimal parameter has been obtained that makes it possible to reduce the calculated bending moment in the cross section of a truss beam with two struts.Method. By equalizing the bending moments in various design sections of the truss beam, the internal force factors are reduced. The corresponding equation for optimizing the parameters of the beam has been drawn up and a formula has been obtained to determine the optimal parameter of the structure as a whole.Result. Using the example of numerical calculations, a decrease in the calculated bending moment by 14% compared to truss beams without optimization is shown.Conclusion. The proposed method and algorithm testify to the efficiency and rationality of the obtained optimal parameter of the structure as a whole.

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