Assessment of Cores Using Electroacoustic Methods

2021 ◽  
Vol 322 ◽  
pp. 214-219
Author(s):  
Sabina Hüblová ◽  
Kristýna Hrabová ◽  
Jaromír Láník ◽  
Petr Cikrle
Keyword(s):  
Reinforced Concrete ◽  
20Th Century ◽  
Compressive Loading ◽  
Concrete Columns ◽  
Reinforced Concrete Columns ◽  
Ultimate Resistance

The paper focuses on the assessment of structures using the methods described in the new edition of the ČSN EN 1371 standard. An experiment will be conducted on cores taken from reinforced concrete columns under compressive loading up to the ultimate resistance. The concrete used to make the column should correspond to old concrete used in the second half of the 20th century. The column will be made with a deliberately created defect - such as stratification or bad compaction of the concrete. When the column is damaged, different degrees of damage to the concrete along its height occur. This can be detected by a thorough examination of cores through the ultrasonic and resonance methods.

scholarly journals Behavior of reinforced concrete columns strenghtened by partial jacketing

2016 ◽  
Vol 9 (1) ◽  
pp. 1-21 ◽  
Author(s):  
D. B. FERREIRA ◽  
R. B. GOMES ◽  
A. L. CARVALHO ◽  
G. N. GUIMARÃES
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Concrete Columns ◽  
The Other ◽  
Self Compacting Concrete ◽  
Reinforced Concrete Columns ◽  
Compressive Stresses ◽  
Concrete Layer ◽  
Ultimate Resistance

This article presents the study of reinforced concrete columns strengthened using a partial jacket consisting of a 35mm self-compacting concrete layer added to its most compressed face and tested in combined compression and uniaxial bending until rupture. Wedge bolt connectors were used to increase bond at the interface between the two concrete layers of different ages. Seven 2000 mm long columns were tested. Two columns were cast monolithically and named PO (original column) e PR (reference column). The other five columns were strengthened using a new 35 mm thick self-compacting concrete layer attached to the column face subjected to highest compressive stresses. Column PO had a 120mm by 250 mm rectangular cross section and other columns had a 155 mm by 250mm cross section after the strengthening procedure. Results show that the ultimate resistance of the strengthened columns was more than three times the ultimate resistance of the original column PO, indicating the effectiveness of the strengthening procedure. Detachment of the new concrete layer with concrete crushing and steel yielding occurred in the strengthened columns.

Experimental and numerical investigations on the size effect of moderate high-strength reinforced concrete columns under small-eccentric compression

2017 ◽  
Vol 27 (5) ◽  
pp. 657-685 ◽  
Author(s):  
Liu Jin ◽  
Zixing Ding ◽  
Dong Li ◽  
Xiuli Du
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Size Effect ◽  
Compressive Loading ◽  
High Strength ◽  
Concrete Columns ◽  
Failure Behavior ◽  
Reinforced Concrete Columns ◽  
Failure Patterns ◽  
Softening Behavior

The paper deals with an experimental investigation and numerical simulation of moderate high-strength reinforced concrete (RC) columns subjected to a small-eccentric compressive loading ( e0 = 0.25 h0). A series of tests on the behavior of 12 geometrically similar moderate high-strength reinforced concrete columns with two different stirrups ratios (i.e., 0% and 0.66%) were conducted. The maximum structural size of the square reinforced concrete columns was 800 mm. A 2D mesoscale method for the simulation of the behavior of reinforced concrete columns was established. The numerical tests on the reinforced concrete columns with larger stirrup ratios (1.2% and 2.4%) were carried out complementarily, based on the fact that the simulation results were consistent with the available test observations. The failure patterns, the nominal compressive stress–strain relationships, the nominal compressive strength, and the post-peak softening behavior of the reinforced concrete columns were studied. Furthermore, the influence of stirrups on failure behavior and size effect of the reinforced concrete columns was revealed. One can conclude that (1) the size effect exists in the nominal compressive strength of the eccentrically loaded high-strength reinforced concrete columns with the four different stirrup ratios; (2) comparison of the present test results and the “size effect law” proposed by Bažant shows good agreement; (3) the presence of stirrups improves the nominal strengths, makes the failure of columns less brittle, and weakens the size effect; and (4) the proposed mesoscale numerical method is capable of describing the mechanical behavior of eccentrically loaded reinforced concrete columns.

SETTING A DIAGRAM APPROACH TO CALCULATING VIBRATED, CENTRIFUGED AND VIBROCENTRIFUGED REINFORCED CONCRETE COLUMNS WITH A VARIATROPIC STRUCTURE

2020 ◽  
pp. 22-34
Author(s):  
Л. Р. Маилян ◽  
С. А. Стельмах ◽  
Е. М. Щербань ◽  
М. П. Нажуев
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Cross Section ◽  
Concrete Columns ◽  
Reinforced Concrete Columns ◽  
The Cross ◽  
Concrete Elements ◽  
Diagram Approach

Состояние проблемы. Железобетонные элементы изготавливаются, как правило, по трем основным технологиям - вибрированием, центрифугированием и виброцентрифугированием. Однако все основные расчетные зависимости для определения их несущей способности выведены, исходя из основного постулата - постоянства и равенства характеристик бетона по сечению, что реализуется лишь в вибрированных колоннах. Результаты. В рамках диаграммного подхода предложены итерационный, приближенный и упрощенный способы расчета несущей способности железобетонных вибрированных, центрифугированных и виброцентрифугированных колонн. Выводы. Расчет по диаграммному подходу показал существенно более подходящую сходимость с опытными данными, чем расчет по методике норм, а также дал лучшие результаты при использовании дифференциальных характеристик бетона, чем при использовании интегральных и, тем более, нормативных характеристик бетона. Statement of the problem. Reinforced concrete elements are typically manufactured according to three basic technologies - vibration, centrifugation and vibrocentrifugation. However, all the basic calculated dependencies for determining their bearing capacity were derived using the main postulate, i.e., the constancy and equality of the characteristics of concrete over the cross section, which is implemented only in vibrated columns. Results. Within the framework of the diagrammatic approach, iterative, approximate and simplified methods of calculating the bearing capacity of reinforced concrete vibrated, centrifuged and vibrocentrifuged columns are proposed. Conclusions. The calculation according to the diagrammatic approach showed a significantly better convergence with the experimental data than that using the method of norms, and also performs better when using differential characteristics of concrete than when employing integral and particularly standard characteristics of concrete.

Experimental Study on the Effect of Moisture Content on Hysteretic Behavior of Reinforced Concrete Columns

2018 ◽  
Vol 12 (1) ◽  
pp. 47-61
Author(s):  
Wenjuan Lv ◽  
Baodong Liu ◽  
Ming Li ◽  
Lin Li ◽  
Pengyuan Zhang
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Moisture Content ◽  
Early Stage ◽  
Damping Ratio ◽  
Concrete Columns ◽  
Hysteretic Behavior ◽  
Cyclic Test ◽  
Experimental Result ◽  
Reinforced Concrete Columns

Background: For reinforced concrete structures under different humid conditions, the mechanical properties of concrete are significantly affected by the moisture content, which may result in a great change of the functional performance and bearing capacity. Objective: This paper presents an experiment to investigate the influence of the moisture content on the dynamic characteristics and hysteretic behavior of reinforced concrete column. Results: The results show that the natural frequency of reinforced concrete columns increases quickly at an early stage of immersion, but there is little change when the columns are close to saturation; the difference between the natural frequencies before and after cyclic test grows as the moisture content rises. The damping ratio slightly decreases first and then increases with the increase of moisture content; the damping ratio after the cyclic test is larger than before the test due to the development of the micro-cracks. Conclusion: The trend of energy dissipation is on the rise with increasing moisture content, although at an early stage, it decreases slightly. According to the experimental result, a formula for the moisture content on the average energy dissipation of reinforced concrete columns is proposed.

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