Proposal for Calculations of Flat Oval Pipes Under Internal Pressure Under Consideration of Material Plastification

1997 ◽  
Vol 119 (3) ◽  
pp. 301-305
Author(s):  
J. Jekerle
Keyword(s):  
Yield Strength ◽  
Internal Pressure ◽  
Wall Thickness ◽  
Cross Sections ◽  
Calculation Method ◽  
Bending Moments ◽  
Normal Stresses ◽  
Shear Forces ◽  
Elastic Bending ◽  
Bending Stresses

In the wall of an oval pipe, additional to the circumferential forces, shear forces and bending moments occur under internal pressure load. Under this condition, the bending stresses in certain cross sections reach a figure many times that of normal stresses so that yield strength of the material can be exceeded. The usual stress calculation method is based on the calculation of the bending moments with the use of the elastic bending equation. The use of the part-plastic equation presented in the paper gives more accurate values for the bending moments sought in the cross sections being checked. This paper shows that even though the new calculation method leads to a smaller wall thickness of the flat oval pipe, the design of the flat oval pipe is nevertheless safe.

scholarly journals Calculation method of the load-bearing frame of a gravity roller rack for boxes

2021 ◽  
Vol 7 (3) ◽  
pp. 251-258
Author(s):  
E.V. Safronov ◽  
A.L. Nosko ◽  
A.S. Guskova
Keyword(s):  
Cross Sections ◽  
Calculation Method ◽  
Bending Moments ◽  
Load Bearing ◽  
Bending Stresses

A method for calculating the frame of a gravity roller rack for boxes based on the disclosure of the static indeterminacy of the system using the equations of three moments is proposed. Unknown reactions from the intermediate supports that provide the overall rigidity of the structure are determined. The maximum bending moments along the length of the entire roller bar are found, and statically definable systems of intermediate supports, front and rear crossbars, and side profiles are calculated. A method for selecting cross-sections of profiles is proposed and their maximum normal bending stresses are calculated, which are compared with the permissible ones.

Shakedown and Limit Analysis of Kinematic Hardening Piping Elbows Under Internal Pressure and Bending Moments

2021 ◽  
Author(s):  
Heng Peng ◽  
Yinghua Liu
Keyword(s):  
Yield Strength ◽  
Internal Pressure ◽  
Limit Analysis ◽  
Kinematic Hardening ◽  
Limit Load ◽  
Bending Moments ◽  
Plastic Limit ◽  
Plastic Limit Load ◽  
Interaction Curves ◽  
Shakedown Limit

Abstract In this paper, the Stress Compensation Method (SCM) adopting an elastic-perfectly-plastic (EPP) material is further extended to account for limited kinematic hardening (KH) material model based on the extended Melan's static shakedown theorem using a two-surface model defined by two hardening parameters, namely the initial yield strength and the ultimate yield strength. Numerical analysis of a cylindrical pipe is performed to validate the outcomes of the extended SCM. The results agree well with ones from literature. Then the extended SCM is applied to the shakedown and limit analysis of KH piping elbows subjected to internal pressure and cyclic bending moments. Various loading combinations are investigated to generate the shakedown limit and the plastic limit load interaction curves. The effects of material hardening, elbow angle and loading conditions on the shakedown limit and the plastic limit load interaction curves are presented and analysed. The present method is incorporated in the commercial finite element simulation software and can be considered as a general computational tool for shakedown analysis of KH engineering structures. The obtained results provide a useful information for the structural design and integrity assessment of practical piping elbows.

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 Assessment of internal pressure effect, causing additional bending of the pipeline

2020 ◽  
Vol 242 ◽  
pp. 160
Author(s):  
Ramil BAKTIZIN ◽  
Rail ZARIPOV ◽  
Gennadii KOROBKOV ◽  
Radik MASALIMOV
Keyword(s):  
Internal Pressure ◽  
Pressure Effect ◽  
Extreme Values ◽  
Bending Moment ◽  
Extreme Value ◽  
Bending Moments ◽  
Temperature Stresses ◽  
Working Pressure ◽  
Trunk Pipeline ◽  
Bending Stresses

Article justifies accounting for internal pressure effect in the pipeline, causing additional bending of the pipeline. According to some scientists, there is an erroneously used concept of the equivalent longitudinal axial force (ELAF) Sx, which depends on working pressure, temperature stresses, and joint deformations of pipelines with various types of soils. However, authors of the article use ELAF Sx concept at construction of mathematical model of stress-strain state (SSS) for complex section of the trunk pipeline, and also reveal it when analyzing the results of calculating the durability and stability of the pipeline. Analysis of SSS for calculated section of the pipeline was carried out for two statements of the problem for different values of operation parameters. In the first statement, effect of internal pressure causing bending of the pipeline is taken into account, and in the second it is neglected. It is shown that due to effect of ELAF Sx at p0 = 9.0 MPa, Dt = 29 °C extreme value of bend increases by 54 %, extreme values of bending stresses from span bending moment increase by 74 %, and extreme value of bending stresses from support bending moment double with regard to corresponding SSS characteristics of the pipeline. In case of neglecting the internal pressure effect causing additional bending of the pipeline (second statement of the problem), error in calculating the extreme value of bend is 35 %, extreme value of bending stresses from span bending moments is 44 %, and extreme value of bending stresses from support bending moments is 95 %.

On Finite Bending of Pressurized Tubes

1959 ◽  
Vol 26 (3) ◽  
pp. 386-392
Author(s):  
Eric Reissner
Keyword(s):  
Internal Pressure ◽  
Cross Sections ◽  
Linear Problem ◽  
Bending Moments ◽  
Pure Bending ◽  
Stability Parameters ◽  
Essential Step ◽  
Circular Rings ◽  
The Stability ◽  
Finite Bending

Abstract A unified treatment is presented of two well-known problems which have until now been considered separately. The two problems are: (a) the linear problem of pure bending of curved tubes, and (b) the nonlinear problem of pure bending of straight tubes. In both problems the effect of uniform internal pressure is included. The essential step in the present analysis is the treatment of the flattening of the cross sections of the tube by means of a theory of finite bending of circular rings. The general results of the paper are used to obtain improved values for the stability parameters in the problem of flattening instability of originally straight tubes acted upon by end bending moments, and also to obtain results on the effect of slight original curvature of the beam axis in the problem of flattening instability.

scholarly journals NUMERICAL APPROACH FOR BENDING STRESS ASCERTAINMENT IN BEAM THEORY CONSIDERING EFFECTS OF ELASTIC SHEAR LAG

2017 ◽  
Vol 9 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Matthias KRAUS
Keyword(s):  
Cross Sections ◽  
Deformation Behaviour ◽  
Beam Theory ◽  
Numerical Approach ◽  
Bridge Engineering ◽  
Bending Moments ◽  
Normal Stresses ◽  
Plane State ◽  
Elastic Shear

In beam theory, normal stresses due to bending moments are usually determined with regard to Bernoullis hypothesis of the cross section staying in a plane state for reasons of simplicity. As a result of this fundamental assumption, the influence of shear on the distribution of normal stresses is not taken into account. However, for cross sections showing wide flanges, as they are commonly applied in bridge engineering for instance, the effect can usually not be disregarded. For the sake of capturing, stiffness oriented numerical approaches allowing the determination of the shear deformation behaviour of cross sections are applied and the shear influence is introduced into the normal stress calculation. This is being exemplarily shown for normal stresses due to bending moments M y.

Comparison Between Predicted and Measured Umbilical Bending Stresses During Manufacturing

2006 ◽  
Author(s):  
Svein Sævik ◽  
Janne K. Gjo̸steen ◽  
Arild Figenschou
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Strain Gauges ◽  
Curvature Radius ◽  
Elastic Bending ◽  
Technical Risk ◽  
Basic Understanding ◽  
Manufacturing Procedure ◽  
Bending Stresses ◽  
The Mathematical Model

The present paper addresses comparison between predicted and measured bending stresses in one umbilical cross section during manufacturing. A factor with significant uncertainties has been which stresses that will occur during the manufacturing procedure when the umbilical is reeled on and off storage drums. The umbilical components may not only be exposed to pure elastic bending stresses due to the curvature radius but also second order axial stresses due to the combination of curvature gradients and finite length to the end fittings. In cooperation with Aker Kværner Subsea a.s., Marintek has developed a tool for stress analysis of Aker Kværner umbilical cross-section designs. The main motivation behind the development has been to reduce technical risk and costs associated with umbilical manufacturing, installation and operation. This is obtained by increasing the basic understanding of the umbilical cross-sections mechanical behaviour and the ability to quantify the stress response when exposed to various loads. In order to calibrate the mathematical model with regard to manufacturing stresses a 70 m long umbilical prototype was instrumented by strain gauges and reeled on an off a storage reel with radius 4.4 m. The paper presents the model applied to simulate this operation as well as the results from comparing predicted and measured stresses.

scholarly journals COMPOUND RUNS OF LOGS CALCULATION: ACCOUNTING OF LONGITUDINAL FORCES’ AND BENDING MOMENTS’ INTERACTION

2020 ◽  
Vol 17 (1) ◽  
pp. 136-149
Author(s):  
V. A. Utkin ◽  
P. N. Kobzev ◽  
E. G. Shatunova
Keyword(s):  
Classical Method ◽  
State Change ◽  
Bending Moments ◽  
Normal Stresses ◽  
Shear Forces ◽  
Load Bearing Capacity ◽  
Composite Girder ◽  
Financial Interest ◽  
Composite Girders

Introduction. Studying the designing and constructing experience of beam bridges with composite log girders indicates the possibility of the load bearing capacity rising of the structures and their further usage in the IV and V categories bridges’ construction under A-11 and H-11 loads. The purpose of the research is to evaluate the effect on the magnitude and distribution of shear forces in shear bonds, considering the permissible pliability of fixation in wood and on the nature of the stress state change in the rods of the composite girders.Materials and methods. The authors presented the construction of the composite girder in the form of three rows united by means of tie bolts and gaskets of four-tier single-row composite girders and made of edged logs. The proposed studying method of a composite girder stress-strain state with discrete placement of concentrated shear bonds in the joints based on the classical method of forces for rod systems, taking into account the interaction of longitudinal forces and bending moments arising in the rods composing the girder of unknown forces in the shear bonds.Results. The determination of single displacements with joint account of bending and stretching-compression deformations haв a significant impact on the redistribution of shear forces in the direction of increasing them in the support zones and reducing them in the middle of the span, and, consequently, on the design of the connecting elements. The character of distribution of normal stresses on the stretching-compression indicated the rods’ girders between relationships under the eccentric compression (stretching).Discussion and conclusions. The proposed solutions demonstrate the most accurate assessment of the composite girders in the structures of spans wooden bridges and present the application possibility in modern conditions.Financial transparency: the authors have no financial interest in the presented materials or methods. There is no conflict of interest.

Nonlinear Theory for Flexural Motions of Thin Elastic Plate, Part 3: Numerical Evaluation of Boundary Layer Solutions

1982 ◽  
Vol 49 (2) ◽  
pp. 409-416
Author(s):  
N. Sugimoto
Keyword(s):  
Boundary Layer ◽  
Stress Singularity ◽  
Free Edge ◽  
Thin Elastic Plate ◽  
Normal Stresses ◽  
Interior Region ◽  
First Order ◽  
Plausible Values ◽  
Bending Stresses ◽  
Order Stress

The boundary layer solutions previoulsy obtained in Part 2 of this series for the cases of the built-in edge and the free edge are evaluated numerically. For the built-in edge, a characteristic penetration depth of the boundary layer toward the interior region is given by 0.13 εh, εh being the normalized thickness of the plate, while for the free edge, it is given by 0.32 εh. Thus the boundary layer for the free edge penetrates more deeply toward the interior region than that for the built-in edge. The first-order stress distribution in each boundary layer is displayed. For the built-in edge, the stress singularity appears on the edge. It is shown that, in the boundary layer, the shearing and normal stresses become comparable with the bending stresses. Similarly for the free edge, the shearing stress also becomes comparable with the twisting stress. It should be remarked that, in the boundary layer, the shearing or the normal stress plays a primarily important role as the bending or the twisting stress. But the former decays toward the interior region and remains higher order than the latter. Finally owing to these numerical results, the coefficients involved in the “reduced” boundary conditions for the built-in edge are evaluated for the various plausible values of Poisson’s ratio.

Large Deflection of a Rectangular Plate Resting on a Pasternak-Type Elastic Foundation

1977 ◽  
Vol 44 (3) ◽  
pp. 509-511 ◽  
Author(s):  
P. K. Ghosh
Keyword(s):  
Rectangular Plate ◽  
Elastic Foundation ◽  
Large Deflection ◽  
Lateral Load ◽  
Bending Moments ◽  
Shear Forces ◽  
Simply Supported ◽  
Base Parameters ◽  
Square Plate

The problem of large deflection of a rectangular plate resting on a Pasternak-type foundation and subjected to a uniform lateral load has been investigated by utilizing the linearized equation of plates due to H. M. Berger. The solutions derived and based on the effect of the two base parameters have been carried to practical conclusions by presenting graphs for bending moments and shear forces for a square plate with all edges simply supported.

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