THE NEED TO TAKE INTO ACCOUNT THE TIME AND OPERATING CONDITIONS OF BUILDINGS AND STRUCTURES WHEN ASSESSING THE FIRE RESISTANCE OF REINFORCED CONCRETE STRUCTURES

Purpose The aim of the research was to investigate the effect of concrete strength on the fire resistance of structures. At first, it may seem contradictory that higher concrete strengths can decrease the fire resistance of building structures. However, if the strength of the concrete exceeds a maximum value, the risk of spalling (the detachment of the concrete surface) significantly. Design/methodology/approach Prefabricated structural elements are often produced with higher strength. The higher concrete strengths generally do not cause a reduction in the load bearing capacity, but it can have serious consequences in case of structural fire design. Results of two prefabricated elements, namely, one slab (TT shaped panel) and one single layer wall panel, were examined. Results of the specimen with the originally designed composition and a specimen with modified concrete composition were examined, were polymer fibres were added to prevent spalling. Findings As a result of the experiments, more strict regulations in the standards the author is suggested including more strict regulations in the standards. It has been proved that to ensure the fire safety of the reinforced concrete structures, it is required after polymer fibres even in lower concrete strength class than prescribed by the standard. In addition, during the classification and evaluation of structures, it is advisable to introduce an upper limit of allowed concrete strength for fire safety reasons. Originality/value As a result of the experiments, the author suggests including more strict regulations in the standards. It has been proved that to ensure the fire safety of the reinforced concrete structures, it is necessary to require the addition of polymer fibres even in lower concrete strength class than prescribed by the standard. In addition, during the classification and evaluation of structures, it is advisable to introduce an upper limit of allowed concrete strength for fire safety reasons.

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Effect of the ITZ Damage on Durability of Reinforced Concrete in Chloride Environment

MRS Proceedings ◽

10.1557/proc-370-465 ◽

1994 ◽

Vol 370 ◽

Cited By ~ 2

Author(s):

Raoul François ◽

Ginette Arliguie

Keyword(s):

Reinforced Concrete ◽

Service Life ◽

Concrete Structures ◽

Operating Conditions ◽

Reinforced Concrete Structures ◽

Actual Operating ◽

Chloride Environment ◽

Concrete Elements ◽

Transfer Properties ◽

Salt Fog

AbstractThis paper deals with the effect of the ITZ on the service life of reinforced concrete. In the case of reinforced concrete structures, the penetration of chlorides does not depend only on concrete transfer properties but also on the loading applied, on the state of strains and on the exposure to the aggressive environment.In order to take into account these different parameters, we have performed experiments on reinforced concrete elements, over a long period. The samples used have to be of an adequate size (3 meters long) and stored in a salt fog in a loading state so as to be representative of the actual operating conditions of the reinforced concrete structures.The bending of the beams leads to the development of cracks which are neither preceded nor accompanied by microcracks, but the cement paste-aggregate interfaces are damaged in the tensile areas.The service loading of reinforced concrete has two consequences : firstly, a cracking with widths ranging between 0.05 mm and 0.5 mm according to the intensity of the mechanical strength applied. Secondly, a damage of the ITZ in the tensile areas causing an increase of chloride penetration directly proportional to the intensity of the stress applied to the beam.The model of the development of corrosion, worked out in relation with time and based on our results, emphasizes the influence of the paste-aggregate interface damage on the duration of the service life.

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Numerical Evaluation of Residual Fire-Resistance of Reinforced Concrete Structures After-Cooling

Proceedings of the Fifteenth International Conference on Civil, Structural and Environmental Engineering Computing ◽

10.4203/ccp.108.16 ◽

2015 ◽

Author(s):

J.-Y. Hwang ◽

H.-G. Kwak

Keyword(s):

Reinforced Concrete ◽

Fire Resistance ◽

Numerical Evaluation ◽

Concrete Structures ◽

Reinforced Concrete Structures

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

ПОЖАРОВЗРЫВОБЕЗОПАСНОСТЬ ◽

10.22227/pvb.2021.30.02.49-70 ◽

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.

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EVALUATION OF FIRE-RESISTANCE OF STRUT REINFORCED CONCRETE STRUCTURES

URBAN CONSTRUCTION AND ARCHITECTURE ◽

10.17673/vestnik.2015.01.13 ◽

2015 ◽

Vol 5 (1) ◽

pp. 82-89 ◽

Cited By ~ 3

Author(s):

Nikolay A. ILYIN ◽

Denis A. PANFILOV ◽

Denis V. LITVINOV ◽

Pavel N. SLAVKIN

Keyword(s):

Reinforced Concrete ◽

Fire Resistance ◽

Fire Hazard ◽

Concrete Structures ◽

Hazard Evaluation ◽

Reinforced Concrete Structures ◽

Engineering Analysis ◽

Temperature Impact ◽

Actual Fire

In SGASU a new engineering solution for buildings fire protection is developped. Its especially efficient for classification of reinforced concrete structures according to their resistance to high-temperature impact in case of fire or technological emergency that gives an opportunity to use a structure with actual fire resistance grading in buildings of different structural fire hazard. Evaluation of actual fi re resistance grading by engineering analysis (as opposed to inplace tests of reinforced concrete structures) makes possible resource and energy saving.

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Increase of Temperature and Fire Resistance for Reinforced-Concrete Structures by Surface Treatment with Protective Coating

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.788.36 ◽

2018 ◽

Vol 788 ◽

pp. 36-44

Author(s):

Liudmyla Demydchuk ◽

Dmytro Sapozhnyk

Keyword(s):

Reinforced Concrete ◽

Fire Resistance ◽

Protective Coating ◽

Concrete Structures ◽

Fire Retardant ◽

Reinforced Concrete Structures ◽

Building Structures ◽

Fire Tests ◽

Normative Documents ◽

Concrete Building

The normative documents of Ukraine (DBN V.1.1.7 ̶ 2016) [1] establish that the limit of fire resistance of reinforced-concrete building structures is determined by the calculation method or by fire tests, and shall be at least 45 minutes. Taking into account the modern construction technologies, namely, the reduction of the section of the main building reinforced-concrete structures, it is expedient to use fire-retardant coatings to provide the necessary fire resistance limit.

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