scholarly journals PLIENINIŲ TINKLINIŲ ARKINIŲ PĖSČIŲJŲ TILTŲ TINKLELIO LYGINAMOJI ANALIZĖ / COMPARATIVE NET ANALYSIS OF THE PEDESTRIAN STEEL NETWORK ARCH BRIDGES

2018 ◽  
Vol 10 (0) ◽  
pp. 1-6
Author(s):  
Sigutė Žilėnaitė
Keyword(s):  
21St Century ◽  
Strain State ◽  
Geometric Analysis ◽  
Search Pattern ◽  
Geometrical Parameters ◽  
Traffic Network ◽  
Bending Moments ◽  
Structural Form ◽  
Arch Bridges ◽  
Buckling Length

Network arch bridges as a new structural form were invented in the middle of 21st century, describing the row of hangers which intersect each other two or more times. The bending moments in the arch and grinder are approximately ten times smaller due to network hangers arrangement. Additionally, an arch buckling length is smaller comparing with traditional vertical hangers, due to the slope of hangers in the network. However, the search pattern of the net rational angle, other composite parameters, and strain-strain state includes only automotive and rail traffic network arched bridges. This paper presents a geometric analysis of the behaviour of network arch pedestrian steel bridges and geometrical parameters of hangers net. Santrauka Tinkliniai arkiniai tiltai – tai XX a. viduryje atsiradusi nauja konstrukcinė tilto forma, apibūdinama mažiausiai dviem eilėmis pasvirusių pakabų, prasilenkiančių viena su kita. Dėl kryžminio pakabų tinklelio arkoje ir standumo sijoje pasireiškia apie 10 kartų mažesni lenkimo momentai nei tradiciniame arkiniame tilte su vertikaliomis pakabomis. Taip pat dėl pasvirusių pakabų tokių tiltų arkos skaičiuojamasis ilgis yra mažesnis nei tradicinių. Pažymėtina, kad tinklelio racionalaus kampo bei kitų komponuojamųjų parametrų paieškos spektras daugelyje tyrimų apima tik automobilių ar geležinkelio eismo paskirties tinklinius arkinius tiltus. Šiame straipsnyje pateikta plieninių tinklinių arkinių pėsčiųjų tiltų elgsenos analizė ir pakabų tinklo geometrinių parametrų paieška.

scholarly journals A Symmetric Three-Layer Plate with Two Coaxial Cracks under Pure Bending

2021 ◽  
Vol 11 (6) ◽  
pp. 2859
Author(s):  
Mykhaylo Delyavskyy ◽  
Viktor Opanasovych ◽  
Roman Seliverstov ◽  
Oksana Bilash
Keyword(s):  
Strain State ◽  
Geometrical Parameters ◽  
Bending Moments ◽  
Algebraic Equations ◽  
Optimum Ratio ◽  
Pure Bending ◽  
Mechanical Quadrature ◽  
Linear Algebraic Equations ◽  
Crack Tips ◽  
Mechanical Quadrature Method

The purpose of this research was to investigate the effect of mechanical features and geometrical parameters on the stress–strain state of a cracked layered plate under pure bending (bending moments are uniformly distributed at infinity). The sixth-order bending problem of an infinite, symmetric, three-layer plate with two coaxial through cracks is considered under the assumption of no crack closure. By using complex potentials and methods of the theory of functions of a complex variable, the solution to the problem was obtained in the form of a singular integral equation. It is reduced to the system of linear algebraic equations and solved in a numerical manner by the mechanical quadrature method. The distributions of stresses and bending moments near the crack tips are shown. Numerical results are presented as graphical dependences of the reduced moment intensity factor on various problem parameters. In this particular case, the optimum ratio of layer thicknesses is determined.

Stiffened Hangers: an Often Overlooked Tool for Conceptual Design of Tied-Arch Footbridges

2021 ◽  
Author(s):  
Juan José Jorquera-Lucerga ◽  
Juan Manuel GARCÍA-GUERRERO
Keyword(s):  
Low Cost ◽  
Three Dimensional ◽  
Structural Response ◽  
Bending Moments ◽  
Structural Element ◽  
Axial Forces ◽  
Limited Effectiveness ◽  
Out Of Plane ◽  
Arch Bridges ◽  
Fixed End

<p>In tied-arch bridges, the way the arch and the deck are connected may become crucial. The deck is usually suspended from hangers made out of steel pinned cables capable of resisting axial forces only. However, a proper structural response, (both in-plane and out-of-plane) may be ensured by fixing and stiffening the hangers in order to resist, additionally, shear forces and bending moments. This paper studies the effect of different pinned and stiffened hanger arrangements on the structural behavior of the tied-arch footbridges, with the intention of providing designers with useful tools at the early steps of design. As a major conclusion, regarding the in-plane behavior, hangers composed of cables (either with vertical, Nielsen-Löhse or network arrangements) are recommended due to its low cost and ease of erection. Alternatively, longitudinally stiffened hangers, fixed at both ends, can be used. Regarding the out-of-plane behavior, and in addition to three-dimensional arrangements of cables, of limited effectiveness, transversally stiffened hangers fixed at both ends are the most efficient arrangement. A configuration almost as efficient can be achieved by locating a hinge at the end corresponding to the most flexible structural element (normally the arch). Its efficiency is further improved if the cross-section tapers from the fixed end to the pinned end.</p>

Research of opening reliability of blast easily disposable systems with honeycomb polycarbonate sheets by finite elements method

2020 ◽  
pp. 107-115
Author(s):  
Yu.Yu. Pidhoretskyi ◽  
Keyword(s):  
Finite Elements ◽  
Strain State ◽  
Numerical Algorithms ◽  
Honeycomb Structure ◽  
Geometrical Parameters ◽  
Stress Strain ◽  
Stress Strain State ◽  
Relief Elements ◽  
Explosion Overpressure ◽  
Applied Approach

In the article, the author presents results of mathematical modeling of operation of the venting relief structures made of honeycomb polycarbonate sheets and fixed in the standard window profiles, under the effect of explosion. In order to reproduce the explosion effect on venting relief structures, an approach to modeling dynamic systems was applied, which used a finite element method to approximate the basic general equations of dynamics added by the equations of the stress-strain state of a solid body. The applied approach differs by reproduction of the explosion process impact on the venting relief structures of this type by using equations which describe the motion of the dynamic system with accounting a contact interaction with the friction of honeycomb polycarbonate sheets and corresponding surfaces of the standard window profile locks. The honeycomb structure of the polycarbonate sheet was modeled by appropriate finite elements with considering the polycarbonate elastic properties. In order to implement numerical algorithms of this approach, a program code of the LS-DYNA computer system was used. The conducted numerical experiment on reproducing the explosion effect on the relief elements of this type of the venting relief structures made it possible to trace all stages of the honeycomb polycarbonate sheets deforming and moving under the action of explosion up to the exit of their edges from the window profile locks with the study of the corresponding stress-strain state parameters. By using this approach, reliably disclosure of the venting relief structures based on honeycomb polycarbonate sheets was investigated, and conditions for their reliable disclosure were identified with considering geometrical parameters of such type of venting relief structures opening and thickness of the honeycomb polycarbonate sheets. Results of the research have shown that reliable disclosure of the honeycomb polycarbonate sheets occurs within the range of the explosion overpressure, hence, confirming the effectiveness of such type of the venting relief structures used for protecting buildings against the explosion action.

scholarly journals REGULARITIES OF THE LINING STRESS-STRAIN STATE DURING OF THE PYLON METRO STATION CONSTRUCTION

2021 ◽  
pp. 19-27
Author(s):  
D. O. BANNIKOV ◽  
V. P. KUPRII ◽  
D. YU. VOTCHENKO
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Finite Elements ◽  
Strain State ◽  
Finite Element Models ◽  
Bending Moments ◽  
Stress Strain ◽  
Normal Forces ◽  
Stress Strain State ◽  
Station Structure

Purpose. Perform numerical analysis of the station structure. Take into account in the process of mathematical modeling the process of construction of station tunnels of a three-vaulted station. Obtain the regularities of the stress-strain state of the linings, which is influenced by the processes of soil excavation and lining construction. Methodology. To achieve this goal, a series of numerical calculations of models of the deep contour interval metro pylon station was performed. Three finite-element models have been developed, which reflect the stages of construction of a three-vaulted pylon station. Numerical analysis was performed on the basis of the finite element method, implemented in the calculation complex Lira for Windows. Modeling of the stress-strain state of the station tunnel linings and the soil massif was performed using rectangular, universal quadrangular and triangular finite elements, which take into account the special properties of the soil massif. Station tunnel linings are modeled by means of rod finite elements. Findings. Isofields of the stress-strain state in finite-element models reflecting the stages of construction are obtained. The vertical displacements and horizontal stresses that are characteristic of a three-vaulted pylon station are analyzed. The analysis of horizontal stresses proved that at the stage of opening of the middle tunnel the scheme of pylon operation is rather disadvantageous. The analysis of bending moments and normal forces was also carried out and the asymmetry of their distribution was noted. Originality. Based on the obtained patterns of distribution of stress-strain state and force factors, it is proved that numerical analysis of the station structure during construction is necessary to take measures to prevent or reduce deformation of frames that are in unfavorable conditions. Practical value. In the course of research, the regularities of changes in stresses, displacements, bending moments and normal forces in the models of the pylon station, which reflect the sequence of its construction, were obtained.

scholarly journals Stress-strain state of a three-layer cylindrical shell under internal axisymmetric pulse load

2020 ◽  
pp. 145-151
Author(s):  
Viktor Gaidaichuk ◽  
Kostiantyn Kotenko
Keyword(s):  
Finite Element ◽  
Cylindrical Shell ◽  
Strain State ◽  
Layer Structure ◽  
Three Dimensional ◽  
Pulse Load ◽  
Geometrical Parameters ◽  
Time Interval ◽  
Stress Strain ◽  
Stress Strain State

The problem of dynamic deformation of a three-layer cylindrical shell under non-stationary loads in the case of rigid clamping of the shell ends is considered. The article presents the results of assessing the stress-strain state of a three-layer cylindrical shell, taking into account its structural feature, the ratio of the sheathing thickness and the physical and mechanical characteristics of a one-piece polymer filler. Calculations were performed by software complex Nastran. The values of displacements and stresses were calculated by the algorithm of direct transient dynamic process. The step duration of the time interval was 0.0000025 s, and the total number of steps was 200. The choice of the type of three-dimensional finite element was due to obtaining more detailed and accurate calculation results. The finite element model included 19000 three-dimensional finite elements and numbered 20800 nodes. The influence of geometrical parameters of shell layers with different physical and mechanical properties of one-piece filler on the stress-strain state under axisymmetric internal impulse load is investigated. Numerical results on the dynamics of the three-layer structure, obtained by the finite element method, allow to characterize the stress-strain state of the three-layer elastic structure of the cylindrical type at any time in the studied time interval. Optimization of the shell design is recommended. Changing the ratio of the thickness of the internal and external shells of the shell significantly affects the stress-strain state of the shell and its performance. Increasing the thickness of the internal layer of the shell significantly contributes to the increase of the latter. Comparison of the given results with materials of other similar researches and positions, testify to objectivity of the made approach.

Research the process of cold punching of hex nut blanks of increased height

2019 ◽  
Vol 75 (8) ◽  
pp. 979-984
Author(s):  
I. G. Shubin ◽  
A. A. Kurkin ◽  
A. R. Bazykov ◽  
F. A. Stolyarov
Keyword(s):  
Strain State ◽  
Metal Flow ◽  
Geometrical Parameters ◽  
Stress Strain ◽  
Industrial Testing ◽  
Stress Strain State ◽  
Metal Deformation ◽  
3D Software ◽  
Through Hole ◽  
Power Costs

The high nuts withstand increased load for expansion, facilitating its even distribution along the bolt length. The process of increased height nut blanks plastic deformation characterized by uneven metal flow and changing of stressed state by the blank section. In the process of closed-die stamping of such nuts a risk of their geometry distortion arises. Results of study of the process of production a hex nut of increased height presented. The object of the research was to study the process of the metal deformation when broach a hole for thread in a hexagonal nut blank of increased height. To simulate the stress-strain state, the QForm-3D software package was chosen, which made it possible to predict with sufficient accuracy the metal flow in the blank, calculate the deformation forces and determine the stresses that occur in the tool. The models of the blank and the tool were created in the Compass 3D program without internal and external defects. When performing the work, the parameters of the stress-strain state of a hexagonal nut blank of increased height were calculated. The simulation results showed the need to change the geometry of the end part of the punch to a conical one with an angle of 150 degrees and a reduction in the size of the baffle height from 10.4 mm to 5.4 mm. The adopted changes allowed to reduce the energy and power costs of forming a through hole for the threads. Industrial testing confirmed the correctness of the calculations. Nuts with edges perpendicular to its base and the required geometrical parameters were obtained.

Exploration on Strengthening Treatment Method of Integral Stressed Bridge under Special Load

2019 ◽  
Vol 4 (1) ◽  
pp. 12-14
Author(s):  
Jiping Liang ◽  
Keyword(s):  
Bridge Deck ◽  
Steel Structure ◽  
Treatment Method ◽  
Transportation Safety ◽  
Structural Form ◽  
Transport Vehicle ◽  
Cargo Transportation ◽  
Pass Through ◽  
Arch Bridges ◽  
Good Operation

The heavy cargo transportation project of the south channel of the Chongqing - Hubei DC back-to-back networking project must pass through the Lianzhu bridge in Enshi City, Hubei Province, China. The bridge crosses the Qingjiang River. The original bridge is two reinforced concrete box independent arch bridges, 146.56m long and 10.74m wide. Since the total weight of the transport vehicle and cargo is 550t and the total length of the vehicle set is 84m, in order to ensure the transportation safety, a steel structure bridge must be added on the existing bridge deck to increase the overall stress of the original bridge. The reinforcement method is the structural form of two bridges under stress at the same time. After the construction is completed and accepted, the heavy cargo transportation task is successfully completed. Now the bridge is in good operation.

scholarly journals Mechanical state analysis of different variants of piled rafts

2015 ◽  
Vol 10 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Michail Samofalov ◽  
Vytautas Papinigis ◽  
Mantas Tūnaitis
Keyword(s):  
Mechanical Properties ◽  
Numerical Simulation ◽  
Strain State ◽  
Design Methods ◽  
Current Paper ◽  
Stress And Strain ◽  
Bending Moments ◽  
Mechanical State ◽  
Piled Raft ◽  
Rational Case

Traditional raft design methods describe unpiled and fully piled rafts. The current paper aims to discuss intermediate raft design variants when the raft is at the same time partially supported by piles and partially rests on the ground. The loading conditions of all variants as well as mechanical properties assumed to be identical, general numerical simulation assumptions are also the same. The task is to analyse the stress and strain state of the raft for all variants (unpiled raft, partially piled raft, fully piled raft), to compare the results and to determine the most rational case. Raft settlements, bending moments and expenses of the materials are compared on the basis of the results.

scholarly journals Multi-scale geometric analysis of Lagrangian structures in isotropic turbulence

2010 ◽  
Vol 654 ◽  
pp. 233-270 ◽  
Author(s):  
YUE YANG ◽  
D. I. PULLIN ◽  
IVÁN BERMEJO-MORENO
Keyword(s):  
Velocity Field ◽  
Isotropic Turbulence ◽  
Geometric Analysis ◽  
Turbulent Velocity ◽  
Geometrical Parameters ◽  
Advection Equation ◽  
Local Geometry ◽  
Multi Scale ◽  
Surface Field ◽  
Turbulent Velocity Field

We report the multi-scale geometric analysis of Lagrangian structures in forced isotropic turbulence and also with a frozen turbulent field. A particle backward-tracking method, which is stable and topology preserving, was applied to obtain the Lagrangian scalar field φ governed by the pure advection equation in the Eulerian form ∂tφ + u · ∇φ = 0. The temporal evolution of Lagrangian structures was first obtained by extracting iso-surfaces of φ with resolution 10243 at different times, from t = 0 to t = Te, where Te is the eddy turnover time. The surface area growth rate of the Lagrangian structure was quantified and the formation of stretched and rolled-up structures was observed in straining regions and stretched vortex tubes, respectively. The multi-scale geometric analysis of Bermejo-Moreno & Pullin (J. Fluid Mech., vol. 603, 2008, p. 101) has been applied to the evolution of φ to extract structures at different length scales and to characterize their non-local geometry in a space of reduced geometrical parameters. In this multi-scale sense, we observe, for the evolving turbulent velocity field, an evolutionary breakdown of initially large-scale Lagrangian structures that first distort and then either themselves are broken down or stretched laterally into sheets. Moreover, after a finite time, this progression appears to be insensible to the form of the initially smooth Lagrangian field. In comparison with the statistical geometry of instantaneous passive scalar and enstrophy fields in turbulence obtained by Bermejo-Moreno & Pullin (2008) and Bermejo-Moreno et al. (J. Fluid Mech., vol. 620, 2009, p. 121), Lagrangian structures tend to exhibit more prevalent sheet-like shapes at intermediate and small scales. For the frozen flow, the Lagrangian field appears to be attracted onto a stream-surface field and it develops less complex multi-scale geometry than found for the turbulent velocity field. In the latter case, there appears to be a tendency for the Lagrangian field to move towards a vortex-surface field of the evolving turbulent flow but this is mitigated by cumulative viscous effects.

Sign in / Sign up

Export Citation Format

Share Document