scholarly journals SHAKING TABLE TESTS ON REINFORCED CONCRETE COLUMNS UNDER BI-DIRECTIONAL EARTHQUAKE MOTIONS : Response characteristics of reinforced concrete structures under bi-directional earthquake motions

1994 ◽  
Vol 59 (455) ◽  
pp. 137-146 ◽  
Author(s):  
Keiji KITAJIMA ◽  
Hiromi ADACHI ◽  
Mitsukazu NAKANISHI
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Concrete Columns ◽  
Shaking Table ◽  
Reinforced Concrete Structures ◽  
Shaking Table Tests ◽  
Reinforced Concrete Columns ◽  
Response Characteristics

A solution to the thermal problem of fire resistance of spun reinforced concrete columns

2021 ◽  
Vol 30 (2) ◽  
pp. 49-70
Author(s):  
I. I. Palevoda ◽  
D. S. Nekhan
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Cross Sections ◽  
Fire Resistance ◽  
Concrete Structures ◽  
Concrete Columns ◽  
Full Scale ◽  
Reinforced Concrete Structures ◽  
Thermal Problem ◽  
Reinforced Concrete Columns

Introduction. Spun reinforced concrete columns are widely used in the present-day international construction practice. Known formulas, used to calculate temperatures of cross sections of reinforced concrete structures, needed to assess their fire resistance limit, are successfully applied to homogeneous structures that have solid sections. However, they are inapplicable to spun reinforced concrete columns due to their structural features. The purpose of this work is to develop a method for solving a thermal problem of spun reinforced concrete columns and adapt existing calculation formulas.Materials and methods. This work addresses the heating of spun reinforced concrete structures in case of fire. Ansys Workbench was employed to perform the computer simulation needed to study the influence of the characteristics of spun reinforced concrete columns on their heating. Results and discussion. In the course of the theoretical studies, the effect, produced by column cavities, the heterogeneity of spun concrete and thin walls of these structures on the heating of their cross sections was assessed with regard for the results of full-scale fire tests of spun reinforced concrete columns. Correction coefficients were obtained in order to take account of these factors. A regression equation was derived as a result of the simulation performed in the context of a full-scale factorial experiment involving coefficient khol, which takes into account the rising temperature of hollow reinforced concrete structures in comparison with solid ones. Khet heating acceleration coefficient is applicable to spun reinforced concrete structures due to the heterogeneity of concrete in the cross section. This coefficient represents a function of the wall thickness. Coefficient kth, which allows for the heating acceleration in the course of crack opening in thin-walled structures, varies in the range of 1.00…1.40. The concrete cracking temperature is 550 °C.Conclusion. A new method allows to solve the thermal problem of fire resistance of spun reinforced concrete columns. The engineering formula used to calculate the temperature in a cross-section was adapted. The results of computer-aided simulation and calculation of temperature values, performed using the adapted formula, show acceptable convergence with the experimental data.

scholarly journals Compressive Performance of Corroded Reinforced Concrete Columns

2020 ◽  
Vol 38 (11A) ◽  
pp. 1618-1628
Author(s):  
Mushtaq S. Radhi ◽  
Maan Hassan ◽  
Iqbal Gorgis
Keyword(s):  
Reinforced Concrete ◽  
Mechanical Performance ◽  
Load Capacity ◽  
Concrete Structures ◽  
Corrosion Damage ◽  
Concrete Columns ◽  
Small Scale ◽  
Uniaxial Compression Test ◽  
Reinforced Concrete Structures ◽  
Reinforced Concrete Columns

Corrosion of reinforcement has been identified as the deterioration mechanism of reinforced concrete structures, which seriously affects the safety and integrity of structures. The corrosion of the embedded reinforcing steel in concrete is a major problem facing civil engineers today, which initiates 80% of the reinforced concrete structures deterioration. This paper reveals the outcomes of an experimental investigation on the mechanical performance (residual strength) of circular steel reinforced columns which have been damaged by corrosion of the steel rebar. Small scale circular reinforced concrete columns with a diameter of 100 mm and 300 mm in height were adopted.  Different rates of steel reinforcement mass loss (corrosion damage) ranged between 10%, 20% to 30 % were created in the columns by using a galvanostatic accelerated corrosion method combined with wetting-drying cycles. The uniaxial compression test was implemented for damaged columns up to failure. Based on the experimental outcomes, it was revealed that the corrosion damage had substantially reduced the performance of columns. The decrement of the load capacity of corroded columns ranged between 19% to 40% and for corrosion, level ranged from 10% to 30%, respectively. The decrement of the final deformation of corroded columns ranged between 15% to 30% and for corrosion, level ranged from 10% to 30%, respectively. Likewise, the failure mode and relationship between the stress and strain for corroded columns had been adversely affected by corrosion.

scholarly journals Optimizing of system "column-cfrp lamellas" with the strengthening of civil structures

2021 ◽  
Vol 9 (1) ◽  
pp. 1-5
Author(s):  
Irina Mayackaya ◽  
Batyr Yazyev ◽  
Anastasia Fedchenko ◽  
Denis Demchenko
Keyword(s):  
Reinforced Concrete ◽  
Composite Materials ◽  
Carbon Fiber ◽  
Concrete Structures ◽  
Polymeric Composite ◽  
Concrete Columns ◽  
Reinforced Concrete Structures ◽  
Structural Elements ◽  
Civil Structures ◽  
Concrete Elements

Reinforced concrete elements of structures in the form of columns, beams, ceilings are widely used in the construction of buildings and structures of industrial and civil construction. In most cases, the columns serve as supports for other building elements, for example, crossbars, slabs, girders, beams. One of the cycles of the work of reinforced concrete structures is the state of their repair and reconstruction, including the stages of strengthening the elements. There is a problem of strengthening of reinforced concrete columns. The article deals with the issue of reinforcing columns and other structural elements having a cylindrical surface, with polymeric composite materials in the form of carbon fiber lamellae. The use of composite materials allows to increase the service life and strength of reinforced concrete structures used in construction.

Confinement of the Concrete Structures by Embedded Composite Grids

2010 ◽  
Vol 425 ◽  
pp. 195-216 ◽  
Author(s):  
Kamal Ait Tahar ◽  
Chateauneuf Alaa
Keyword(s):  
Reinforced Concrete ◽  
Composite Materials ◽  
Human Life ◽  
Concrete Structures ◽  
Concrete Columns ◽  
The Other ◽  
Reinforced Concrete Structures ◽  
Numerical Studies ◽  
Composite Grids ◽  
Concrete Matrix

Composite materials have shown their efficiency in improving the mechanical properties of concrete structures, in addition to ensuring better resistance to environmental conditions. Reinforced concrete structures are often very sensitive to accidental loads, leading to deterioration, failures and human life fatalities. The reinforcement of concrete columns by composite materials, judiciously integrated in the concrete matrix, has the advantage of offering sufficient rigidity and strength to prevent overall collapse, on one hand, and, to preserve external and esthetic aspects of reinforced concrete works, on the other hand. The experimental and numerical studies in the present work represent a promising revelation regarding the effectiveness of the proposed confinement process by integrating a composite grid inside the reinforced concrete matrix. The concepts of single and double confinement are developed and discussed on the basis of experimental results for concrete specimens.

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