Discussion on Several Problems in the Study of Corrosion Mechanism of Steel - Concrete Composite Beams

2013 ◽  
Vol 368-370 ◽  
pp. 888-891
Author(s):  
Qing Yuan Li ◽  
Zhi Wu Yu ◽  
Ya Chuan Kuang
Keyword(s):  
Composite Beam ◽  
Composite Beams ◽  
Performance Degradation ◽  
Practical Significance ◽  
Steel Beams ◽  
Corrosion Mechanism ◽  
Reinforcement Corrosion ◽  
Research Directions ◽  
Number Of Factors ◽  
The Future

It’s of great practical significance to improve the durability of steel-concrete composite beam structures.The deterioration of steel-concrete composite beams includes stud rust, reinforcement corrosion, corrosion of the steel beams and concrete performance degradation, which are caused by a number of factors. The corrosion mechanism of composite beams is discussed, and some basic issues remain to be solved in this area are analyzed in the paper. Besides, some research directions in the future are put forward.

scholarly journals Fire Resistance of Composite Beams with Restrained Superposed Slabs

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Junli Lyu ◽  
Qichao Chen ◽  
Huizhong Xue ◽  
Yongyuan Cai ◽  
Jingjing Lyu ◽  
...  
Keyword(s):  
Fire Resistance ◽  
Composite Beam ◽  
Composite Beams ◽  
Thermomechanical Coupling ◽  
Temperature Fields ◽  
Steel Beams ◽  
Experiment Data ◽  
Temperature Distributions ◽  
Uniformly Distributed Loads ◽  
Deformation Recovery

To investigate the fire resistance of composite beams with restrained superposed slabs, three specimens were tested under uniformly distributed loads in a furnace. The effects of the thickness of the postcast top layer in superposed slabs and the spacing of shear studs on the structural behaviours of composite beams under fire were further examined. During the tests, the temperature distributions of the superposed slabs and steel beams as well as the displacements at their key positions were recorded and analysed. It was found that the temperature of the concrete superposed slabs decreased long their heights from the bottom. The most drastic change of the temperature along the slab cross section was found in the region with a distance of 40 mm to the slab bottom. The concrete superposed slabs could impose restraints to the steel beams due to their incompatible deformations. Cracks were developed on the top surfaces of the specimens and the superposing interfaces between the precast slabs and postcast top layers were not broken. Through the comparisons of different specimens, the spacing of shear studs could have a significant effect on the fire resistance of composite beams, especially for their deformation recovery capacities. In contrast, the effect of the thickness of the postcast top layers was negligible. ABAQUS was employed to simulate the temperature fields and deformation behaviours of composite beam specimens based on a sequenced thermomechanical coupling analysis. The numerical results agreed well with the experiment data, which validated the developed numerical model.

Editor’s Pick: Regulatory and Ethical Issues in the New Era of Radiomics and Radiogenomics

EMJ Radiology ◽  
2020 ◽  
Author(s):  
Filippo Pesapane
Keyword(s):  
Ethical Issues ◽  
Medical Images ◽  
Practical Significance ◽  
Innovative Technology ◽  
New Era ◽  
Naked Eye ◽  
Disease Characteristics ◽  
The Future ◽  
Using Data ◽  
The Relationship

Radiomics is a science that investigates a large number of features from medical images using data-characterisation algorithms, with the aim to analyse disease characteristics that are indistinguishable to the naked eye. Radiogenomics attempts to establish and examine the relationship between tumour genomic characteristics and their radiologic appearance. Although there is certainly a lot to learn from these relationships, one could ask the question: what is the practical significance of radiogenomic discoveries? This increasing interest in such applications inevitably raises numerous legal and ethical questions. In an environment such as the technology field, which changes quickly and unpredictably, regulations need to be timely in order to be relevant.  In this paper, issues that must be solved to make the future applications of this innovative technology safe and useful are analysed.

scholarly journals Longitudinal shear capacity of the slabs of composite beams

1976 ◽  
Vol 3 (4) ◽  
pp. 514-522 ◽  
Author(s):  
M. N. El-Ghazzi ◽  
H. Robinson ◽  
I. A. S. Elkholy
Keyword(s):  
Composite Beam ◽  
Shear Failure ◽  
Concrete Slab ◽  
Compressive Force ◽  
Longitudinal Shear ◽  
Composite Beams ◽  
Shear Capacity ◽  
Slab Width ◽  
Two Parameters ◽  
Concrete Elements

The longitudinal shear failure of the slab of composite beams is constrained to occur at a predetermined shear surface. A method for calculating the longitudinal shear capacity of the slab of simply-supported steel–concrete composite beams is presented. The method is based on analyzing the stresses at failure of the concrete elements located at the slab shear surface.A design chart based on estimating the transverse normal stress required within the concrete slab to achieve the full ultimate flexural capacity of the composite beam is proposed. Alternatively, using elastic–plastic stress distribution across the concrete slab, the longitudinal compressive force due to bending and hence the applied moment can be predicted for any longitudinal shear capacity of the slab. The proposed design and analysis when compared to previous tests and analysis showed good agreement.The slab width and the shear span of the composite beam are found to be two important parameters which cannot be neglected when estimating the longitudinal shear capacity of the slab. These two parameters have been neglected in the empirical solutions previously adopted.

Legal Basis for United Nations Armed Forces

1962 ◽  
Vol 56 (4) ◽  
pp. 971-996 ◽  
Author(s):  
John W. Halderman
Keyword(s):  
United Nations ◽  
Armed Forces ◽  
Practical Significance ◽  
Legal Basis ◽  
The Future

The question of the legal basis for United Nations armed forces is one of immense practical significance for the future effectiveness of the organization in keeping the peace.

scholarly journals Experimental Study on Timber−Lightweight Concrete Composite Beams with Ductile Bolt Connectors

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2632
Author(s):  
Yafeng Hu ◽  
Yang Wei ◽  
Si Chen ◽  
Yadong Yan ◽  
Weiyao Zhang
Keyword(s):  
Composite Beam ◽  
Lightweight Concrete ◽  
Experimental Testing ◽  
Composite Beams ◽  
Strengthening Effect ◽  
Bending Performance ◽  
Maximum Deformation ◽  
Bending Failure ◽  
Push Out ◽  
Timber Beams

A timber–lightweight−concrete (TLC) composite beam connected with a ductile connector in which the ductile connector is made of a stainless−steel bolt anchored with nuts at both ends was proposed. The push−out results and bending performance of the TLC composite specimens were investigated by experimental testing. The push−out results of the shear specimens show that shear–slip curves exhibit good ductility and that their failure can be attributed to bolt buckling accompanied by lightweight concrete cracking. Through the bending tests of ten TLC composite beams and two contrast (pure timber) beams, the effects of different bolt diameters on the strengthening effect of the TLC composite beams were studied. The results show that the TLC composite beams and contrast timber beams break on the timber fiber at the lowest edge of the TLC composite beam, and the failure mode is attributed to bending failure, whereas the bolt connectors and lightweight concrete have no obvious breakage; moreover, the ductile bolt connectors show a good connection performance until the TLC composite beams fail. The ultimate bearing capacities of the TLC composite beams increase 2.03–3.5 times compared to those of the contrast beams, while the mid-span maximum deformation decrease nearly doubled.

Monotonic and fatigue assessment of steel-concrete composite beams strengthened with externally post-tensioned tendons

2018 ◽  
Author(s):  
◽  
Ayman Elzohairy
Keyword(s):  
Numerical Model ◽  
Composite Beam ◽  
Composite Beams ◽  
Fatigue Tests ◽  
Flexural Behavior ◽  
Bending Test ◽  
Steel Beam ◽  
Premature Failure ◽  
Post Tensioning ◽  
Post Tensioned

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The steel-concrete composite beam represents a structural system widely employed in both buildings and girder bridges. The coupling between steel beams and concrete flanges assures both economic and structural benefits because of quick construction of steel structures and large increase in stiffness due to the presence of concrete. Strengthening with external post-tensioning (PT) force is particularly effective and economical for long-span steel-concrete composite beams and has been employed with great success to increase the bending and shear resistance and correct excessive deflections. Applying external PT force to the steel-concrete composite beam is considered an active strengthening technique that can create permanent internal straining action in the beam which is opposite to the existing straining action due to the applied service loads. The most benefits of using this system of strengthening are an elastic performance to higher loads, higher ultimate capacity, and reduction in deformation under the applied loads. Under service loads, bridge superstructures are subjected to cyclic loads which may cause a premature failure due to fatigue. Therefore, fatigue testing is critical to evaluate existing design methods of steel-concrete composite beams. ... This research presents static and fatigue tests on four steel-concrete composite specimens to evaluate the effect of externally post-tensioned tendons on the ultimate strength and fatigue behavior of composite beams. Fatigue tests are conducted to a million cycles under a four-point bending test. In addition, final static tests are performed on fatigued specimens to evaluate the residual strength of the strengthened specimen. A numerical model is described to predict the fatigue response of the composite beam by considering the fatigue damage in the concrete flange. The accuracy of the developed numerical model is validated using the existing test data. The static test results indicate that the external post-tensioning force improves the flexural behavior of the strengthened specimen by increasing the beam capacity and reducing the tensile stress in the bottom flange of the steel beam. The fatigue results demonstrate that the external post-tensioning significantly decreases the strains in the shear connectors, concrete flange, and steel beam. The tendons demonstrated an excellent fatigue performance, with no indication of distress at the anchors.

scholarly journals Reliability of beams designed in accordance with Brazilian codes

2014 ◽  
Vol 7 (5) ◽  
pp. 723-746 ◽  
Author(s):  
D. M. Santos ◽  
F. R. Stucchi ◽  
A. T. Beck
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Composite Beams ◽  
Reinforced Concrete Beams ◽  
Steel Beams ◽  
Structural Elements ◽  
Pure Bending ◽  
Design Standards ◽  
Limit Values ◽  
Relative Safety

This paper presents an investigation on the safety of structural elements submitted to pure bending, produced in reinforced concrete, in steel and steel-concrete composites, and designed according to Brazilian codes NBR8681:2003, NBR6118:2007 and NBR8800:2008. The study allows a comparison of the relative safety of beams produced with these materials and designed using these codes. Comparative studies between the performances of different materials are difficult to find in the published literature. The present study shows that reliability indexes for reinforced concrete beams are satisfactory; however, results for steel beams are below limit values established in international design standards. Reliability indexes found herein for steel-concrete composite beams are intermediate to concrete and steel beams.

scholarly journals Flexural Interpretation of Simply Supported Laminated Composite Beam

2020 ◽  
Vol 8 (5) ◽  
pp. 3559-3565
Keyword(s):  
Shear Deformation ◽  
Composite Beam ◽  
Laminated Composite ◽  
Beam Theory ◽  
Composite Beams ◽  
Shear Stresses ◽  
Bending Stress ◽  
Simply Supported ◽  
Laminated Composite Beam ◽  
Laminated Composite Beams

In this Paper, the analysis of simply supported laminated composite beam having uniformly distributed load is performed. The solutions obtained in the form of the displacements and stresses for different layered cross ply laminated composite simply supported beams subjected uniformly distributed to load. Different aspect ratio consider for different results in terms of displacement, bending stress and shear stresses. The shear stresses are calculated with the help of equilibrium equation and constitutive relationship. Using displacement field including trigonometric function of laminated composite beams are derived from virtual displacement principle. There are axial displacement, transverse displacement, bending stress and shear stresses. In addition, Euler-Bernoulli (ETB), First order shear deformation beam theory (FSDT), Higher order shear deformation beam theory (HSDT) and Hyperbolic shear deformation beam theory (HYSDT) solution have been made for comparison and better accuracy of solutions and results of static analyses of laminated composite beams for simply supported laminated composite beam.

scholarly journals КОМПЛЕКСНАЯ ОЦЕНКА КОНКУРЕНТОСПОСОБНОСТИ ПЕРЕРАБОТАННОЙ ПЛОДООВОЩНОЙ ПРОДУКЦИИ

2019 ◽  
pp. 6-12
Author(s):  
Н. Р. Асадуллина
Keyword(s):  
Practical Significance ◽  
Vegetable Production ◽  
Fruit And Vegetable ◽  
Transport Costs ◽  
Expert Opinions ◽  
Number Of Factors ◽  
Vegetable Products ◽  
Quality Of Products ◽  
The Cost

Formulation of the problem. The article reflects the assessment of the competitiveness of processed fruit and vegetable products, the qualitative characteristics of fruit and vegetable products are substantiated, as well as the parameters of the degree of consistency of expert opinions based on the calculation of the concordance coefficient. The purpose of the research is to reflect and characterize existing methods of integrated assessment of the competitiveness of processed fruit and vegetable products. The object of research – the process of determining the quality of products produced, as well as the competitiveness of processed fruit and vegetable products. The methods used in the research – logical, comparative, analytical, scientific and methodological. The hypothesis of the research is to assume the dependence of the competitiveness of processed fruit and vegetable products and its sales volumes. The statement of basic materials. The buyer prefers products depending on the purpose and use of this product. In the course of further processing, the buyer pays attention to the volume of packaging, the suitability of the packaging for the content of the product in it, the maximum time for the storage of products. The article suggests such indicators of quality of processed fruit and vegetable production: biochemical composition of products; packaging of products; design and design of products; appearance and consistency; terms of product suitability; cost of production per kilogram of production. The originality and practical significance of the research is that the author substantiates the degree of influence of the proposed indicators on competitiveness on the basis of expert assessments. The number of points is determined depending on the number of factors considered. The degree of consensus of expert opinions is established on the basis of calculating the coefficient of concordation. Conclusions of the research. In the process of packaging the product and its production must take into account the directions of its use. For further industrial consumption, processed fruit and vegetable products can be made with a higher content of dry soluble substances, vitamins, sugars, and acidity. This will save on the cost of packaging, transport costs, and handling operations.

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