3D Analysis of Bridges Changing Structural Systems – An Easy Design Tool

2015 ◽  
Vol 796 ◽  
pp. 69-75
Author(s):  
Vladimír Křístek ◽  
Lukáš Kadlec
Keyword(s):  
Cross Sections ◽  
Design Tool ◽  
Structural Systems ◽  
Concrete Bridge ◽  
3D Analysis ◽  
Box Girders ◽  
Reliable Determination ◽  
The Real ◽  
Bridge Structures ◽  
Primary Advantage

Due to increase of requirements on accuracy of structural analyses, practically applicable computational tools for reliable determination of the real structural performance of bridges are needed. A method is proposed for the true full 3D analysis which can be applied to achieve the real spatial behaviour of concrete bridge structures taking into account rheological phenomena and changes of structural systems. Particularly, the effects of shear lag, shear performance of webs of box girders, warping torsion, warping of cross-sections, distortional effects, state of stresses in the singular regions, the real prestress loss, etc., can be correctly determined. The method combines conventional approaches (based on the elementary beamtype assumptions) for calculating the time development of the internal forces due to rheological phenomena and changes in the structural system during construction and routine commercial FEM software intended for calculating spatial shell structures. The method is capable to give the true 3D prediction of structure behaviour by using only commercially available software. The primary advantage of the proposed method is its ease of application which allows the true 3D performance to be determined from simple calculations. The method offers the designers of concrete bridge girders an ideal design tool. The correct 3D simulation can lead to more efficient and economical designs.

THE APPLICATION OF THE MODIFIED GLAUBER MODEL II FOR THE DESCRIPTION PROTON-NUCLEUS SCATTERING: EFFECT OF RELATIVISTIC AND NON-RELATIVISTIC OPTICAL POTENTIALS

2003 ◽  
Vol 12 (06) ◽  
pp. 845-862
Author(s):  
HUSSEIN M. A. AHMED ◽  
E. H. ESMAEL
Keyword(s):  
Experimental Data ◽  
Dirac Equation ◽  
Cross Sections ◽  
Glauber Model ◽  
Nuclear Potential ◽  
Spin Orbit ◽  
Reliable Determination ◽  
The Real ◽  
Optical Potentials ◽  
The Impact

Calculations of total reaction cross-sections and differential cross-sections using the modified Glauber model II for p –16 O scattering in the energy range 100–497.5 MeV are compared with experimental data. The real parts of the nuclear central potential and spin-orbit potential were used to calculate the modified Glauber model II. The nuclear potential was constructed using two approaches: the Dirac-equation-based optical potential and the non-relativistic treatment. The phenomenological and analytical methods are used to calculate these two approaches. The strength of the real parts of central and spin-orbit potentials are normalized to the best fit to the data. The best values were obtained close to unity. Most of the calculations derived from the Dirac-equation-based optical potentials were more comparable with the experimental data than the non-relativistic calculations. This may be attributed to the delicate cancellation between the short-range repulsive and the long-range attractive contributions. The present investigation indicated that a good choice of the potential at given energy offers a reliable determination of the impact parameter estimated according to the modified Glauber model II.

Evaluation of web reinforcements in prestressed concrete box girders through shear-transverse bending domains

2020 ◽  
pp. 136943322098170
Author(s):  
Michele Fabio Granata ◽  
Antonino Recupero
Keyword(s):  
Analytical Model ◽  
Prestressed Concrete ◽  
3D Analysis ◽  
Box Girders ◽  
Element Analysis ◽  
Cross Sectional ◽  
Interaction Domains ◽  
Global And Local ◽  
Resultant Forces

In concrete box girders, the amount and distribution of reinforcements in the webs have to be estimated considering the local effects due to eccentric external loads and cross-sectional distortion and not only the global effect due to the resultant forces of a longitudinal analysis: shear, torsion and bending. This work presents an analytical model that allows designers to take into account the interaction of all these effects, global and local, for the determination of the reinforcements. The model is based on the theory of stress fields and it has been compared to a 3D finite element analysis, in order to validate the interaction domains. The results show how the proposed analytical model allows an easy and reliable reinforcement evaluation, in agreement with a more refined 3D analysis but with a reduced computational burden.

The Preparation of Submicron Precision Cross Sections by Dimpling With A ‘Flatting Tool’

1997 ◽  
Vol 480 ◽  
Author(s):  
Helen L. Humiston
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Microstructural Analysis ◽  
Complex Materials ◽  
Ion Milling ◽  
Step Procedure ◽  
Simple Step ◽  
Primary Advantage ◽  
Preparation Techniques ◽  
Support Grid

AbstractThe complex materials systems in VLSI devices require specialized preparation techniques for TEM microstructural analysis. For this purpose, it is desirable to obtain electron transparency in all material layers from the oxides used in dielectrics to refractory metals such as tungsten. The primary advantage of dimpling these materials is that ideal specimens are obtained for low angle ion milling. By dimpling both sides of the cross section with a padded flatting tool, a thicker specimen of 130μm at the outer rim of the 3mm disc is produced that narrows to the 125nm thickness fringes in the center. These samples do not require a copper support grid, thereby allowing for a lower milling angle of 2.5 degrees on both sides of the specimen. This technique provides a cross section that is electron transparent in all layers without the loss of oxides due to differential thinning rates of various materials at higher milling angles.It is generally thought that precision thinning through a submicron feature is not possible on the dimpler. However, a simple step-by-step procedure for this technique will be demonstrated and discussed.

Shear Assessment of Concrete Bridge Deck Slabs

2017 ◽  
Vol 738 ◽  
pp. 110-119 ◽  
Author(s):  
Radoslav Vida ◽  
Jaroslav Halvonik
Keyword(s):  
Current Model ◽  
Shear Capacity ◽  
Concrete Bridge ◽  
Current Standard ◽  
Concrete Members ◽  
Deck Slabs ◽  
Bridge Structures ◽  
Bridge Deck Slabs ◽  
Concrete Bridge Deck ◽  
New Generation

The transitions from old STN standards to Eurocode standards brought several problems into bridge design and assessment. Shear reinforcement is now often required even in concrete members, which were previously allowed to be built without it. Moreover, assessment of existing reinforced concrete bridge structures often shows their insufficiency in shear capacity, which means that they should be strengthened or replaced. Work on new generation of Eurocodes is currently in progress and current model for shear assessment should be replaced by a new (and more precise) one. This paper deals with the problem of shear assessment of concrete bridge according to current standard and also according to the new shear models that are under consideration.

scholarly journals Elastic scattering and breakup reactions with light proton- and neutron-rich exotic nuclei

2018 ◽  
Vol 194 ◽  
pp. 07002
Author(s):  
M.K. Gaidarov ◽  
V.K. Lukyanov ◽  
D.N. Kadrev ◽  
E.V. Zemlyanaya ◽  
A.N. Antonov ◽  
...  
Keyword(s):  
Experimental Data ◽  
Elastic Scattering ◽  
Cross Sections ◽  
Cluster Model ◽  
Microscopic Analysis ◽  
High Energy ◽  
The Real ◽  
Optical Potentials ◽  
Generator Coordinate ◽  
Energy Approximation

A microscopic analysis of the optical potentials (OPs) and cross sections of elastic scattering of 8B on 12C, 58Ni, and 208Pb targets at energies 20 < E < 170 MeV and 12,14Be on 12C at 56 MeV/nucleon is carried out. The real part of the OP is calculated by a folding procedure and the imaginary part is obtained on the base of the high-energy approximation (HEA). The density distributions of 8B evaluated within the variational Monte Carlo (VMC) model and the three-cluster model (3CM) are used to construct the potentials. The 14Be densities obtained in the framework of the the generator coordinate method (GCM) are used to calculate the optical potentials, while for the same purpose both the VMC model and GCM densities of 12Be are used. In the hybrid model developed and explored in our previous works, the only free parameters are the depths of the real and imaginary parts of OP obtained by fitting the experimental data. The use of HEA to estimate the imaginary OP at energies just above the Coulomb barrier is discussed. In addition, cluster model, in which 8B consists of a p-halo and the 7Be core, is applied to calculate the breakup cross sections of 8B nucleus on 9Be, 12C, and 197Au targets, as well as momentum distributions of 7Be fragments. A good agreement of the theoretical results with the available experimental data is obtained. It is concluded that the reaction studies performed in this work may provide supplemental information on the internal spatial structure of the proton- and neutron-halo nuclei.

scholarly journals Acoustic Emission Monitoring of Multicell Reinforced Concrete Box Girders Subjected to Torsion

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Marya Bagherifaez ◽  
Arash Behnia ◽  
Abeer Aqeel Majeed ◽  
Chai Hwa Kian
Keyword(s):  
Acoustic Emission ◽  
Reinforced Concrete ◽  
Cross Sections ◽  
Analysis Data ◽  
Damage Localization ◽  
Box Girders ◽  
Box Girder ◽  
Value Analysis ◽  
Damage Propagation ◽  
Torsion Fracture

Reinforced concrete (RC) box girders are a common structural member for road bridges in modern construction. The hollow cross-section of a box girder is ideal in carrying eccentric loads or torques introduced by skew supports. This study employed acoustic emission (AE) monitoring on multicell RC box girder specimens subjected to laboratory-based torsion loading. Three multicell box girder specimens with different cross-sections were tested. The aim is to acquire AE analysis data indicative for characterizing torsion fracture in the box girders. It was demonstrated through appropriate parametric analysis that the AE technique could be utilized to effectively classify fracture developed in the specimens for describing their mechanical behavior under torsion. AE events localization was presented to illustrate the trend of crack and damage propagation in different stages of fracture. It could be observed that spiral-like patterns of crack were captured through AE damage localization system and damage was quantified successfully in different stages of fracture by using smoothedb-value analysis.

STATIC AND DYNAMIC PERFORMANCE EVALUATION OF A PRE-STRESSED CONCRETE BRIDGE THROUGH FIELD TESTING AND MONITORING

2009 ◽  
Vol 09 (04) ◽  
pp. 711-728 ◽  
Author(s):  
C. S. CAI ◽  
M. ARAUJO ◽  
A. NAIR ◽  
X. SHI
Keyword(s):  
Quantitative Methods ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Field Tests ◽  
Field Measurements ◽  
Field Testing ◽  
Concrete Bridge ◽  
Bridge Structures ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

This paper presents field tests performed on a slab-on-girder pre-stressed concrete bridge. The bridge was tested under static loading, crawling loading, and dynamic loading. A full three-dimensional finite element prediction under both static and dynamic loadings was carried out and the results were compared with the field measurements. While acoustic emission (AE) monitoring of bridge structures is not a new vista, the method has not been fully exploited in bridge monitoring. Though numerous quantitative methods have been proposed, they have not yet developed to be useful for actual field tests of bridges. Therefore, in this study, an attempt was made to use the intensity analysis technique for damage quantification using the AE method.

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