scholarly journals Stress-deformation state of compound reinforced concrete bars with high-strength reinforcement prone to long-term compression

Vestnik MGSU ◽  
2019 ◽  
pp. 1121-1131
Author(s):  
Kristina I. Zarakovskaya ◽  
Vladimir F. Zakharov
Keyword(s):  
Reinforced Concrete ◽  
Stress State ◽  
Calculation Method ◽  
High Strength ◽  
Longitudinal Reinforcement ◽  
Deformation State ◽  
Stress Deformation ◽  
Strain Stress ◽  
Compound Section

Introduction. Considering that reinforced concrete is the most common material in construction and reconstruction of buildings and facilities, research of work of high-strength reinforcement in reinforced concrete elements, including compressed columns, are still relevant at present. Analysis of compound-section columns with high-strength longitudinal reinforcement is of particular interest since the method of sectional build-up is widespread enough in the reconstruction of buildings and facilities. However, no information on the work of this kind of reinforced concrete structures under long-term compression was found either in foreign or domestic literature; this fact provides relevance and academic novelty of the study. Materials and methods. The article provides the research of parameters of the strain-stress state of compound reinforced concrete bars with high-tensile reinforcement under long time compression employing the modern methods of mathematical simulation. Results. The developed calculation method allows determining additional parameters of the strain-stress state of the compressed compound-section reinforced concrete bars considering the concrete creep deformations forming in time of the long-term compression. When comparing the analytical study results with authors’ experimental data and previous results of other researchers, an adequate degree of reliability of the developed calculation method was confirmed. Conclusions. When applying the developed calculation method of stress-deformation state parameters for the compressed compound-section columns with high-strength longitudinal reinforcement, the study discovered that significant effort redistribution from concrete to high-strength reinforcement occurs under long-term compression. This fact was confirmed with the results of an experimental investigation on the resistance of the compound reinforced concrete bars with high-tensile reinforcement to the longtime compression.

Critical review of CSA A23.3-94 deflection prediction for normal and high strength concrete beams

1998 ◽  
Vol 25 (3) ◽  
pp. 474-489 ◽  
Author(s):  
Alaa G Sherif ◽  
Walter H Dilger
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Bending Moment ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
Bilinear Method ◽  
Short And Long Term ◽  
The Mean ◽  
Effective Moment Of Inertia

The purpose of this paper is to critically review the provisions of CSA A23.3-94 for the deflection calculations of normal and high strength reinforced concrete beams. Comparison is made with the provisions of CEB-FIP MC 90 and EC 2 which is similar to the MC 90. Both short- and long-term deflections are discussed. Tests from the literature are used to assess the calculation methods suggested by the codes. These methods are the effective moment of inertia approach, the mean curvature approach, and the bilinear method. A parametric study is carried out to investigate the effect of the level of loading, shape of bending moment, and reinforcement ratio on the predicted deflections.Key words: code predictions, deflections, long term, reinforced concrete beams, short term.

Studies on Long-Term Deflection of FRP Reinforced Concrete Beams

2013 ◽  
Vol 438-439 ◽  
pp. 811-814 ◽  
Author(s):  
Quan Ji Han ◽  
Hai Tang Zhu ◽  
Hai Bo Cui
Keyword(s):  
Reinforced Concrete ◽  
Influencing Factors ◽  
Calculation Method ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Research Status

The research status and progress, in China and overseas, of long-term deflection of FRP reinforced concrete beams are briefly introduced in this paper. The mechanism, influencing factors and calculation method of long-term deflection of FRP reinforced concrete beams are discussed and summarized. Meanwhile, some advices for long-term deflection research of FRP reinforced concrete beams are proposed.

scholarly journals Prepared experimental study for durability verification of FRP reinforced concrete members

2021 ◽  
Vol 1209 (1) ◽  
pp. 012055
Author(s):  
S Blaho ◽  
K Gajdošová
Keyword(s):  
Experimental Study ◽  
Reinforced Concrete ◽  
Concrete Structures ◽  
High Strength ◽  
Bending Test ◽  
Reinforced Concrete Structures ◽  
Reinforced Polymers ◽  
Concrete Members ◽  
Four Point Bending

Abstract Major advantage of fibre reinforced polymers (FRPs) is their high strength and low weight to strength ratio. These are also the main reasons for a choice for this material in the process of design of reinforced concrete structures. Since there is no corrosion of FRP, this reinforcement could be strongly recommended for concrete reinforcement in aggressive environment. Till today there is no sufficient knowledge of long-term behaviour of FRP-reinforced concrete structures. Design codes give low utilization capacity of FRP materials and are not supposed to be correct according to the real behaviour in a few experiments of last decades. Reduction factors limit the mechanical properties in the range from 0.95 for CFRP to 0.5 for GFRP. In the paper there is presented a prepared and today realized long-term experimental study based on four point bending test on simply supported concrete beams reinforced with GFRP reinforcement.

Deformation of Steel-Reinforced Concrete Round Thin Slabs Taking into Account the Compliance of the Support Contour

2021 ◽  
Vol 887 ◽  
pp. 680-690
Author(s):  
Kh.S. Razzokov
Keyword(s):  
Reinforced Concrete ◽  
Stress State ◽  
Strain State ◽  
Experimental Studies ◽  
Concrete Slabs ◽  
Governing Equations ◽  
Short Term ◽  
Steel Reinforced Concrete ◽  
Normalized Parameters

The paper presents the governing equations of bending of nonlinearly deformable, axisymmetrically loaded round, thin reinforced concrete and steel concrete slabs, taking into account the work of a non-deformable and pliable support contour. Based on the results of theoretical and experimental studies, the stress-strain state of reinforced concrete and steel-concrete slabs under short-term and long-term loadings was estimated. The nature of stress state is revealed in the stages of cracking and destruction of plates. The work of the slabs in the field of elastic, elastoplastic and plastic stages of work is estimated. Using the method of limiting equilibrium, a method for calculating steel-concrete slabs for strength with normalized parameters.

scholarly journals Reinforcement impact on the stress-deformation state of concrete faced rockfill dam

Vestnik MGSU ◽  
2019 ◽  
pp. 347-355 ◽  
Author(s):  
Mikhail P. Sainov ◽  
Andrei Y. Shigarov ◽  
Sofia A. Iasafova
Keyword(s):  
Reinforced Concrete ◽  
Steel Reinforcement ◽  
Control Element ◽  
Tensile Stresses ◽  
Rockfill Dam ◽  
Reinforcement Percentage ◽  
Deformation State ◽  
Stress Deformation ◽  
The Face ◽  
Concrete Face

ABSTRACT Introduction. The article considers results of research of reinforced-concrete face stress-deformation state depending on availability of the reinforcement. At some ultra-high reinforced-concrete faced rockfill dams (CFRD) the transversal (horizontal) cracks were developed in the seepage-control element. It is supposed that the cause of the crack formation is high values of tensile stresses. In this connection, opinions are expressed about the necessity of strengthening the face reinforcement. However, in accordance with the experience gained, in real dams the reinforcement, as a rule, is arranged in one row with reinforcement percentage 0.35 to 0.5 %. The urgent issue of CFRD studies is assessment of impact of the concrete face strengthened reinforcement on enhancement of its reliability. Materials and methods. The studies were conducted for different variants of rock fill deformation properties on the example of 100 m high rockfill dam. The reinforced concrete face was adopted to be wide (1 m thick). The reinforcement was adopted to be two-row one, with reinforcement percentage of 1.5 %. The study was conducted using the finite element method. The reinforcement was simulated using bar finite elements. Results. To reveal the role of reinforcement, analyses of the stress-deformation state were conducted for two cases. In one case it was assumed that reinforcement is absent and in the other case consideration was made for the face with steel reinforcement. Stresses in concrete and steel reinforcement were analysed. Stresses acting along the upstream slope were considered. Conclusions. It was revealed that due to the reinforcement of steel-bar reinforced concrete face it was impossible to provide decrease of tensile stresses in the face concrete down to the permissible level. Reinforcement may play a significant role in the face stress-deformation state only at the moment of forming transversal cracks in the face concrete, but such a case is inadmissible.

scholarly journals Design of reinforced concrete slabs subject to the construction joints

Vestnik MGSU ◽  
2019 ◽  
pp. 1106-1120
Author(s):  
Andrei V. Deineko ◽  
Valentina A. Kurochkina ◽  
Irina Yu. Yakovleva ◽  
Aleksandr N. Starostin
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structure ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Reinforced Concrete Structure ◽  
Construction Joint ◽  
Floor Slabs ◽  
Deformation State ◽  
Stress Deformation ◽  
Construction Joints

Introduction. When erecting monolithic reinforced concrete floor slabs, a necessity of construction joints arises. The construction joints are the areas of structural weakening. The construction practice shows that the compliance with the correct technology of the construction joint arrangement is not a sufficient condition to ensure the strength balance of reinforced concrete floor slabs. As a result, the stress-deformation state calculated on the assumption of the concrete slab solidity deviates from the actual state. The relevance of the task is determined by the fact that the conformity of design and actual characteristics of the in-situ reinforced concrete structures as a whole depends on the correct calculations of construction joints. Materials and methods. The problem of implementing the construction joints in the monolithic floor slabs was considered by way of example of a residential building under construction. In the course of construction, pre-construction land surveys were carried out at the areas of the construction joint arrangement. Calculations of reinforced concrete structures using finite element method (FEM) were also performed. Results. As a result of the study, the actual deflections of the floor slabs were measured at the areas of the construction joints and FEM calculations were made on the same floor slabs, both those erected at once and those erected in stages subject to the construction joints. The difference between the calculated and actual deflections is conditioned upon the inaccurate conformity between the mathematical model and the real reinforced concrete structure, its erection and maintenance conditions. It should be noted that the deflection of horizontal reinforced concrete structures is only one of the stress-deformation state parameters that can be measured better than the others. It is shown that if the deflection of a real reinforced concrete structure does not correspond with the design estimation, the other stress-deformation state parameters will differ from the design estimation as well. Conclusions. The influence of joints can be taken into account in the scope of FEM computer-aided calculations with the explicit reproduction of the structure erection by pouring concrete, using engineering approach to the consideration of nonlinearity on the basis of the introducing reduction coefficients to the reinforced concrete effective modulus of elasticity. Solid composition modeling of reinforced concrete provides the best possibilities on taking all sorts of nonlinearity manifestations into consideration.

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