scholarly journals Deformation of rockfill in bodies of rockfill dams

2019 ◽  
pp. 5-5
Author(s):  
Mikhail Sainov
Keyword(s):  
Reinforced Concrete ◽  
Deformation Modulus ◽  
Deformation Model ◽  
Observation Data ◽  
Linear Deformation ◽  
Laboratory Test Results ◽  
Wide Range ◽  
Deformation Properties ◽  
Non Linear ◽  
The Impact

Introduction. The main factor determining the stress-strain state (SSS) of rockfill dam with reinforced concrete faces is deformability of the dam body material, mostly rockfill. However, the deformation properties of rockfill have not been sufficiently studied yet for the time being due to technical complexity of the matter, Materials and methods. To determine the deformation parameters of rockfill, scientific and technical information on the results of rockfill laboratory tests in stabilometers were collected and analyzed, as well as field data on deformations in the existing rockfill dams. After that, the values of rockfill linear deformation modulus obtained in the laboratory and in the field were compared. The laboratory test results were processed and analyzed to determine the parameters of the non-linear rockfill deformation model. Results. Analyses of the field observation data demonstrates that the deformation of the rockfill in the existing dams varies in a wide range: its linear deformation modulus may vary from 30 to 500 МPа. It was found out that the results of the most rockfill tests conducted in the laboratory, as a rule, approximately correspond to the lower limit of the rockfill deformation modulus variation range in the bodies of the existing dams. This can be explained by the discrepancy in density and particle sizes of model and natural soils. Only recently, results of rockfill experimental tests were obtained which were comparable with the results of the field measurements. They demonstrate that depending on the stress state the rockfill linear deformation modulus may reach 700 МPа. The processing of the results of those experiments made it possible to determine the parameters on the non-linear model describing the deformation of rockfill in the dam body. Conclusions. The obtained data allows for enhancement of the validity of rockfill dams SSS analyses, as well as for studying of the impact of the non-linear character of the rockfill deformation on the SSS of reinforced concrete faces of rockfill dams.

scholarly journals Analysis and settlement evaluation of an end-bearing granular pile with non-linear deformation modulus

2018 ◽  
Vol 40 (3) ◽  
pp. 188-201 ◽  
Author(s):  
Jitendra Kumar Sharma ◽  
Pooja Gupta
Keyword(s):  
Influence Factor ◽  
Ground Improvement ◽  
Deformation Modulus ◽  
Relative Length ◽  
Stone Columns ◽  
Linear Deformation ◽  
Dense Sand ◽  
Granular Pile ◽  
Non Linear ◽  
Granular Piles

AbstractGround improvement with granular piles increases the load-carrying capacity, reduces the settlement of foundations built on the reinforced ground and is also a good alternative to concrete pile. Granular piles or stone columns are composed of granular material, such as crushed stone or coarse dense sand. An analytical approach based on the continuum approach is presented for the non-linear behaviour of the granular pile. The formulation for pile element displacement is done considering the non-homogeneity of the granular pile as it reflects the true behaviour and also accounts for the changes in the state of the granular pile due to installation, stiffening and improvement effects. The present study shows that the settlement influence factor for an end-bearing granular pile decreases with increase in the relative stiffness of the bearing stratum. The settlement influence factor decreases with increase in linear and non-linear non-homogeneity parameters for all values of relative length. For a shorter pile, the rate of decrease of the settlement influence factor is greater in comparison to that for a longer pile. Shear stress at the soil–granular pile interface reduces in the upper compressible portion of the granular pile and increases in the lower stiffer portion of the granular pile due to the non-homogeneity of an end-bearing granular pile.

scholarly journals Calculation of damage RC constructions according to deformation model

2020 ◽  
Vol 2020 (2) ◽  
pp. 99-106
Author(s):  
Yaroslav Blikharskyy ◽  
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Concrete Structures ◽  
Physical And Mechanical Properties ◽  
Reinforced Concrete Beams ◽  
Core Material ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
The Impact

This article presents results of a theoretical study of reinforced concrete beams with damaged reinforcement. The change of micro-hardness of a reinforcing rebar’s with a diameter of 20 mm of A500C steel in the radial direction is investigated and the thickness of the heat-strengthened layer is established. It is established that the thickness of the thermo-strengthened steel layer of the reinforcing bar with a diameter of 20 mm of A500C is approximately 3 mm. It is shown that the strength characteristics of this layer are on 50% higher compared to the core material of the rebar, while the plasticity characteristics are lower. The aim of the work is to determine the strength and deformability of reinforced concrete structures without damaging the reinforcement and in case of damage. Determining the impact of changes in the physical characteristics of reinforcement on the damage of reinforced concrete structures, according to the calculation to the valid norms, in accordance with the deformation model. To achieve the goal of the work, theoretical calculations of reinforced concrete beams were performed according to the deformation model, according to valid norms. This technique uses nonlinear strain diagrams of concrete and rebar and is based on an iterative method. According to the research program 3 beam samples were calculated. Among them were undamaged control sample with single load bearing reinforcement of ∅20 mm diameter – BC-1; sample with ∅20 mm reinforcement with damages about 40% without changes in the physical and mechanical properties of reinforcement – BD-2 and sample with ∅20 mm reinforcement with damages about 40% with changes in the physical and mechanical properties of reinforcement – BD-3. The influence of change of physical and mechanical characteristics of rebar’s on bearing capacity of the damaged reinforced concrete beams is established.

scholarly journals Increasing the Performance of a Fiber-Reinforced Concrete for Protective Facilities

Fibers ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 64
Author(s):  
Roman Fediuk ◽  
Mugahed Amran ◽  
Sergey Klyuev ◽  
Aleksandr Klyuev
Keyword(s):  
Reinforced Concrete ◽  
Impact Strength ◽  
Impact Energy ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Secondary Cracks ◽  
Wide Range ◽  
Long Time ◽  
The Impact ◽  
Hardening Coefficient

The use of fiber in cement materials is a promising and effective replacement for bar reinforcement. A wide range of fiber-reinforced concretes based on composite binders with increased impact strength characteristics have been developed. The synthesized composites included the composite binder made of Portland cement, silica, and carbonate additives. Basalt and steel were used as fibers. The nature of the influence of the composition and manufacturing technology of cement composites on the dynamic hardening coefficient has been established, while the growth of these indicators is achieved by creating a denser interfacial transition zone between the cement paste, aggregate, and fiber as a result of improving the homogeneity of the concrete mixture and controlling the consistency. Workability indicators (slump flow up to 730 mm; spreading time up to a diameter of 50 cm is up to 3 s) allow them to be classified as self-compacting concrete mixtures. An increase in the values of the impact strength coefficient by a factor of 5.5, the dynamic hardening coefficient by almost 70% as a result of interfacial interaction between fibers and binder matrix in the concrete composite, as well as absorption of impact energy by fiber, was revealed. The formula describing the effect of the loading rate on the coefficient of dynamic hardening of fiber-reinforced concrete has been refined. The fracture processes of the obtained materials have been established: after the initiation of primary cracks, the structure of the composite absorbs impact energy for a long time, while in the inelastic range (the onset of cracking and peak loads), a large number of secondary cracks appear.

scholarly journals THE ANALYSIS OF THE DISCRETE CRACKING MODEL OF REINFORCED CONCRETE TENSILE MEMBERS

2010 ◽  
Vol 2 (4) ◽  
pp. 146-156
Author(s):  
Donatas Salys ◽  
Gintaris Kaklauskas ◽  
Edgaras Timinskas ◽  
Viktor Gribniak ◽  
Darius Ulbinas ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Stress Transfer ◽  
Bond Stress ◽  
Experimental Program ◽  
Deformation Analysis ◽  
Tension Stiffening ◽  
Bond Slip ◽  
Secondary Cracks ◽  
Wide Range ◽  
Deformation Properties

Adequate modelling of reinforced concrete (RC) cracking, particularly post-cracking behaviour (tension stiffening), as one of the major sources of nonlinearity, is the most important and difficult task for deformation analysis. Deformationbehaviour of the cracked RC members is a complex process, including a wide range of effects such as differentstrength and deformation properties of steel and concrete, concrete cracking, tension-softening and tension-stiffening,bond slip between reinforcement and concrete etc. Even under low load, behaviour can be non-linear, which presents a challenge for calculating the deformations of RC members.When stress in concrete first reaches tensile strength at the weakest section,cracking occurs. After the formation of the first primary crack up to the final one, concrete contribution steadily decreases. At the final cracking point, the stable crack pattern has been reached. Increase in load will result in a further decrease of concrete contribution due to bond-slip causing cover-controlled cracks to develop between the primary cracks and a gradual breaking down of the bond. This process can be imagined as the formation of internal secondary cracks along the deformed bar due to bond stress transfer to sound concrete in between primary cracks. Total stresses in the cracked tensile reinforcement consisted of genuine stresses corresponding to the average strain of steel and additional stresses due to tension-stiffening. The internal forces that represent the latter stresses are called the residual and can be used for assessing the average bond behavior of RC members. This paper investigates tension-stiffening effect in RC members. The discrete cracking model of RC member is described in the paper. The discussed approach is based on bond-slip relationship that models the bond-action between concrete and reinforcement. This approach is realistically capable of modelling cracking and determining crack widths and deformations. However, the accuracy of calculation results depends on the assumed bond stress-slip relationship. A number of recent investigations aimed at developing and modifying such models were performed intending that discrete cracking modelling technique could become a powerful tool for the analysis of reinforced concrete members. The present study is dedicated to deformation analysis of reinforced members that are subjected to pure tension and is based on the results of the experimental program reported in literature. The average deformations of such members were calculated applying the discrete cracking method using different bond stress-slip relationships and compared with test results reported in literature. It was concluded that relationship recommended by CEB-FIP MC90 was unacceptable for the analysis performed.

scholarly journals Non-linear deformation properties of materials with stochastically distributed anisotropic inclusions

PAMM ◽  
2013 ◽  
Vol 13 (1) ◽  
pp. 253-254 ◽  
Author(s):  
Lidiia Nazarenko ◽  
Swantje Bargmann ◽  
Leonid Khoroshun
Keyword(s):  
Linear Deformation ◽  
Deformation Properties ◽  
Non Linear ◽  
Properties Of Materials

scholarly journals A theoretical framework for BL Her stars – I. Effect of metallicity and convection parameters on period–luminosity and period–radius relations

2020 ◽  
Vol 501 (1) ◽  
pp. 875-891
Author(s):  
Susmita Das ◽  
Shashi M Kanbur ◽  
Radoslaw Smolec ◽  
Anupam Bhardwaj ◽  
Harinder P Singh ◽  
...  
Keyword(s):  
Linear Models ◽  
State Of The Art ◽  
Large Magellanic Cloud ◽  
Radiative Cooling ◽  
Instability Strip ◽  
Stellar Pulsation ◽  
Empirical Relations ◽  
Wide Range ◽  
Non Linear ◽  
The Impact

ABSTRACT We present a new grid of convective BL Herculis models using the state-of-the-art 1D non-linear radial stellar pulsation tool mesa-rsp. We investigate the impact of metallicity and four sets of different convection parameters on multiwavelength properties. Non-linear models were computed for periods typical for BL Her stars, i.e. 1 ≤ P(d) ≤ 4 covering a wide range of input parameters – metallicity (−2.0 dex ≤ [Fe/H] ≤ 0.0 dex), stellar mass (0.5–0.8 M⊙), luminosity (50–300 L⊙), and effective temperature (full extent of the instability strip; in steps of 50 K). The total number of BL Her models with full-amplitude stable pulsations used in this study is 10 280 across the four sets of convection parameters. We obtain their multiband (UBVRIJHKLL′M) light curves and derive new theoretical period–luminosity (PL), period–Wesenheit (PW), and period–radius (PR) relations at mean light. We find that the models computed with radiative cooling show statistically similar slopes for PL, PW, and PR relations. Most empirical relations match well with the theoretical PL, PW, and PR relations from the BL Her models computed using the four sets of convection parameters. However, PL slopes of the models with radiative cooling provide a better match to empirical relations for BL Her stars in the Large Magellanic Cloud in the HKS bands. For each set of convection parameters, the effect of metallicity is significant in U and B bands and negligible in infrared bands, which is consistent with empirical results. No significant metallicity effects are seen in the PR relations.

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