scholarly journals The theory of degradation for polymer concrete in complex stress state

2019 ◽  
Vol 135 ◽  
pp. 01054
Author(s):  
Yuliya Moreva ◽  
Andrey Varlamov ◽  
Yuliya Novoselova
Keyword(s):  
Stress State ◽  
Uniaxial Compression ◽  
Complex Structure ◽  
Experimental Studies ◽  
Complex Stress ◽  
Complex Stress State ◽  
Polymer Concrete ◽  
Steel Shell ◽  
Concrete Core ◽  
Energy Characteristics

The article discusses the features of the application of the theory of degradation to the work of an integrated structure operating in a complex stress state. The analysis of the work of an integrated structure consisting of a steel shell filled with concrete (core structure). Based on the analysis of the construction work, we obtained the relations connecting the deformations of the steel shell and the polymer concrete core of the complex structure. The obtained relations made it possible to apply the diagrams of concrete work for uniaxial compression to analyze the possibility of using concrete as a core of an integrated structure. Experimental studies of the polymer concrete core of the structure were conducted. In total, ten concrete compositions were made and investigated. The compositions of concrete differed in cementitious: cement and polyester resin. As a filler used sand, gravel, ground clay, marble flour, soda and fine mineral fibers. Samples were tested for central and eccentric compression. During the tests used the methods used in testing cement concrete. As a result of the tests, complete schedules of the work of materials for uniaxial compression were obtained. The analysis of the energy characteristics of concrete schedules based on the theory of degradation is carried out. As a result of the discussion of the results obtained, conclusions are drawn about the possibility of using polymer concrete as the supporting core of an integrated structure with an external steel shell.

scholarly journals BEHAVIOUR OF HOLLOW CONCRETE‐FILLED STEEL TUBULAR COMPOSITE ELEMENTS

2007 ◽  
Vol 13 (2) ◽  
pp. 131-141 ◽  
Author(s):  
Artiomas Kuranovas ◽  
Audronis Kazimieras Kvedaras
Keyword(s):  
Stress State ◽  
Elasticity Modulus ◽  
Complex Stress ◽  
Steel Tube ◽  
Complex Stress State ◽  
Test Results ◽  
Load Bearing Capacity ◽  
Concrete Core ◽  
Theoretical Investigations ◽  
Concrete Elements

Behaviour of composite steel‐concrete elements in various loading stages is quite well analysed by theoretical investigations and experiments. Concrete‐Filled Steel Tube (CFST) is one of many composite elements used at present in civil engineering. Different approaches and design philosophies were adopted in different design codes for it. But for hollow CFST elements, which are more effective than ordinary CFST, any code does not provide information about how to design these elements. Further investigations of hollow composite CFST elements are needed. In loading stage, when a particular level of stresses exists, an interaction between steel tube and concrete core appears and therefore a complex stress state of element takes place, which increases the load‐bearing capacity of the whole composite element. This interaction between components of CFST elements is reached because of different material properties, such as Poisson's ratio, elasticity modulus etc. In this article reasons of the above‐mentioned complex stress state appearance and behaviour of hollow CFST element components in different load stages of compressed stub structural member are analysed. The test results are presented in diagrams, tables. Previous researches of other investigators are summarised. Differences and similarities in behaviour of solid concrete and composite elements and hollow members with different number of concrete core layers are discussed.

scholarly journals Compressed Concrete Filled Steel Tube Elements of Annular Cross-Section

2018 ◽  
pp. 144-148
Author(s):  
Vladimir I. Rimshin ◽  
Anatoly L. Krishan ◽  
Evgenia A. Troshkina
Keyword(s):  
Cross Section ◽  
Complex Stress ◽  
Steel Tube ◽  
Complex Stress State ◽  
Steel Shell ◽  
Mechanics Of Solids ◽  
Concrete Core ◽  
Concrete Filled Steel Tube ◽  
Annular Cross Section ◽  
Initial Modulus

The problem of determining the strength of a short centrally compressed concrete-filled steel tube element of annular cross-section is considered. The corresponding calculation procedure is proposed. The procedure is based on the theoretical positions of the mechanics of solids and it implements the method of limiting forces. It considers the complex stress state of the concrete core and steel shell as well as nonuniform distribution of transversal stresses over the cross-section of the calculated element. If there is high-strength reinforcement in the concrete, the stress in it is calculated considering the increased deformability of the concrete. The dependences for determining the initial modulus of elasticity of concrete as well as ultimate relative strains of uniaxially compressed and volumetrically compressed concrete are presented. The proposed procedure is applicable to structures made of different concrete types and steel classes.

scholarly journals NONLINEAR DEFORMATION-FORCE MODEL OF A CONCRETE BAR WITH NON-METALLIC COMPOSITE REINFORCEMENT IN THE GENERAL CASE OF A STRESSED STATE

2021 ◽  
Vol 3 (1) ◽  
pp. 6-26
Author(s):  
I. Karpiuk ◽  
◽  
Ye. Klymenko ◽  
V. Karpiuk ◽  
M. Karpiuk ◽  
...  
Keyword(s):  
Stress State ◽  
Stressed State ◽  
Bearing Capacity ◽  
Nonlinear Deformation ◽  
Complex Stress ◽  
Complex Stress State ◽  
Force Model ◽  
Metallic Composite ◽  
Aggressive Environment ◽  
Deformation Force

The article discusses a nonlinear deformation-force model of a concrete bar structure with a non-metallic composite reinforcement (NKA-FRP) in the general case of a stressed state, when all four internal force factors from an external load (namely, bending and twisting moments, transverse and longitudinal forces). A sufficiently deep and meaningful analysis of well-known studies on the selected topic is given. It has been established that the proposed nonlinear deformation-force model of a bar structure with FRP in the general case of a stressed state can be practically useful due to the possibility of its application in the design or reinforcement of beams, girders, columns and elements of rosette trusses of rectangular cross-section, which are operated under aggressive environmental conditions. This model can also be used to check the bearing capacity of existing FRP concrete bar structures, which operate not only under the influence of an aggressive environment, but also under conditions of a complex stress-strain state. In the course of the research, an algorithm was developed for determining the bearing capacity of the design section of a concrete rod with FRP under its complex stress state. General physical relations for the design section are given in the form of a stiffness matrix. The algorithm for calculating a concrete bar with FRP consists of a block for inputting the initial data, the main part, auxiliary subroutines for checking the conditions for increasing the load vector and depletion of the bearing capacity, as well as a block for printing the calculation results. At each stage of a simple static stepwise increasing load, the calculation is carried out by performing a certain number of iterations until the accuracy of determining all components of the deformation vector satisfies a certain predetermined value. The features and patterns of changes in normal and tangential stresses, generalized linear and angular deformations, as well as the equations of equilibrium of a concrete bar with FRP, which operates under the influence of an aggressive environment under conditions of a complex stress state, are also considered.

Micromechanical Analysis of SiC/Ti6Al4V Composite Under Complex Stress State

2022 ◽  
Author(s):  
Pengjian Zou ◽  
Xuming Niu ◽  
Xihui Chen ◽  
Zhigang Sun ◽  
Yan Liu ◽  
...  
Keyword(s):  
Stress State ◽  
Complex Stress ◽  
Complex Stress State ◽  
Micromechanical Analysis

Application of the concept of criterion of a complex stress state to a simple tension for appraisal of resistance of fatigue of structural materials. Part 2. Drawing up criterion and its checking on compliance to experimental data

2021 ◽  
pp. 41-45
Author(s):  
P.N. Kozlov
Keyword(s):  
Experimental Data ◽  
Stress State ◽  
Structural Material ◽  
Complex Stress ◽  
Complex Stress State ◽  
Static Loads ◽  
Regular Change ◽  
Regular Cycle ◽  
Simple Tension ◽  
Dangerous Point

The criterion for appraisal of resistance of fatigue of structural material at action on it of repeatedly variables loads and static loads in the form of a bend or tensioncompression together with torsion, and also at action of loads, which create two-axis regular change of stress state in a dangerous point of material is constructed. The received criterion will acceptable be coordinated with the known experimental data. Keywords: dangerous point of material, regular cycle of loading, equivalent amplitude, equivalent average stress, chart of extreme amplitudes of stresses. [email protected]

scholarly journals A statistical method for predicting the eccentric load capacity of rectangular concrete filled steel tubular columns

2020 ◽  
Vol 313 ◽  
pp. 00031
Author(s):  
Glib Vatulia ◽  
Maryna Rezunenko ◽  
Dmytro Petrenko ◽  
Yevhen Balaka ◽  
Yevhen Orel
Keyword(s):  
Carrying Capacity ◽  
Load Capacity ◽  
Experimental Studies ◽  
Integrated Approach ◽  
Steel Shell ◽  
Eccentric Load ◽  
Concrete Core ◽  
Eccentric Compression ◽  
The Impact ◽  
Longitudinal Strains

The article deals with the integrated approach to the study of the behaviour of rectangular CFST columns under eccentric compression. Such an approach includes the development of methods for assessing the magnitude of the carrying capacity, assessing the degree of reliability and credibility of the obtained results, as well as studying the nature of the development of columns deformations at various stages of loading. The authors developed a mathematical model for calculation of columns carrying capacity under eccentric compression based on statistical methods. Substantial amount of experimental data collected by the world leading laboratories enabled obtaining a regression dependence of the columns carrying capacity that takes into account the impact of the physical and geometric characteristics of such structures. High degree of model confidence is confirmed by a comparative analysis with experimental results that are not involved in the development of the model, as well as with calculations performed according to Eurocode, Japanese and Chinese regulatory documents. The article presents experimental studies of the nature of deformations development on the surface of the steel shell and inside the concrete core of various lengths rectangular columns. As a result of the experimental tests, it was established that the longitudinal strains of the compressed area of the shell have the most significant impact on the bearing capacity of eccentrically compressed steel concrete samples.

Evaluation of Properties of Constructed Tubular-Steel Cast-in-Place Pilings

2013 ◽  
Vol 2363 (1) ◽  
pp. 36-46
Author(s):  
Devin K. Harris ◽  
Amir Gheitasi ◽  
Theresa M. Ahlborn ◽  
Kevin A. Mears
Keyword(s):  
Compressive Strength ◽  
Experimental Studies ◽  
Ground Surface ◽  
Axial Loading ◽  
Steel Shell ◽  
Deep Foundations ◽  
Element Analysis ◽  
Concrete Core ◽  
Geometrical Properties ◽  
Wisconsin Department

Bridge foundations contribute significantly to the serviceability and efficiency of in-service transportation networks. Foundation failure may lead to catastrophic failure of the entire structure, which in turn results in system failure, loss of life, and detours. When the soil within ground surface layers fails to satisfy the bearing capacity requirements, deep foundations such as tubular-steel concrete-filled piles are commonly used in practice. A challenge that often exists with these systems is the uncertainty surrounding in-service capacity as well as condition, which is difficult to determine from the surface. As a consequence, transportation agencies such as the Wisconsin Department of Transportation use conservative approaches, such as neglecting the tubular-steel contribution or bounding the compressive strength of the core concrete, to design these systems. This approach, while effective for safety, can yield overly conservative and costly designs. The main purpose of this investigation was to evaluate the behavior of tubular-steel, concrete-filled, cast-in-place pilings, with a concentration on the compressive strength and composite behavior between concrete core and steel shell. In this regard, a series of experimental studies, including composite and noncomposite compression loading, core samples, push-through, and flexural testing together with a compatible finite element analysis, were conducted on a series of field-cast piles with different geometrical properties. The results indicated that the steel shell made a significant contribution to the axial loading capacity of the cast-in-place piles. Moreover, no evidence of bond loss was observed during the corresponding experimental studies.

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