The Fire Resistance Performance of Concrete Columns with Different Compressive Strength

Four full concrete columns have been created Tested below high temperature for The re resistance of concrete elements in concrete with particular compressive strengths. The standard concrete with compressive strength values of C25 were made of one of the four specimens, while the rest were made of C35, C60 and C75 respectively, respectively. During simulation of Within the laboratory furnace, the same For the specimens, axial forces were applied. Many experimental outcomes parameters were evaluated in contrast, including temperature changes, Vertical moving, side deection, re resistance and Failed properties of the specimen. The results have shown a rise in the compressive strength of the concrete for the concrete columns from the outside up to the inside of the column. Of columns of the the same cross section of the lower compressive forces of concrete display better re resistance eciency with the same initial axial strength ratio. The C35, C60 and C75 columns' re resistance is higher than standard concrete columns. The initial and secant rigidity of the columns of Reinforced concrete ( RC) has also The percentage decreased dramatically after re exposure and the temperature increased from 25 to 750 ° C.


Introduction
Many researchers have been studying the behavior of Reinforced Concrete (RC) exposed to re over the last two decades. Understanding the column behavior at high temperatures helps to assess the re protection degree of the structure. The overall load for a column exposed to re was indicated to be 20-40 % Lower than the column before the re [1]. A major decrease in the elasticity module was also observed at high temperatures which showed a 62-72 percent decreases after heating up to 400 ° C.
Several experiments have been carried out based Concrete part re output. Lie et al. [2,3] and other Canadian citizens in the 1990s researchers conducted studies with re resistance, primarily on standard Filled RC columns and tubular steel columns with changed pieces of concrete, available their formula for re resistance, now used by the global construction industry. In Kodur et al. [4,5] and Iguchi et al. [6] regular concrete RC beams and columns were studied re resistance. Gernay et al. [7] structural performance of natural res in concrete columns was investigated.
The modern form of environmental-friendly material recycled aggregate concrete (RAC), using waste concrete to substitute natural aggregates for recycled materials, is rendered partly or completely by washing, grinding, grading and mixing methods. Sarhat et al. [ 8] examined RAC's residual mechanical response following hightemperature exposure. However, only when the RC column re resistance e ciency with different intensities was investigated, few re resistance experimental concert studies of RC structures and materials perforated. The principal structural elements of most buildings are vertical columns and the loss of load-bearing capacity in the re causes the entire structure to be partially or entirely demolished. Work on the e ciency of RC columns to protect life and property in re situations is thus important. The results show that specimens with a high column have a lower temperature than standard concrete, load power, strength and re conditions in the same place. Fire endurance decreases as specimen strength increases.
In this paper, On the basis of experimental data, the e ciency of re resistance was evaluated of three RC columns and one Standard RC columns of speci c compressive concrete forces. in order to give an experimental basis for the use of the design of re-resistance using different concrete compressive strengths.

Resources And Goals
The debate above indicates that ductility and energy absorption and column rigidity are important, because safety is guaranteed in these columns when natural disasters happen. The ductile behavior of the columns before and after the re is more important during the re as at the beginning of the column's vital sections it provides a visible warning, with no severe resistance loss, which in effect provides the building a time to safe evacuation and to ensure the protection of the re-ghters. Until now, however, only relatively few studies have concentrated on Ductility study, energy absorption potential and column rigidity. Data showing the status of these characteristics after the re has been released are also lacking.
This study aims to collect and raise knowledge in this area in order to address the gaps in science. The main objective of such work conducts investigational analysis to investigate Effect on ductility, energy e ciency and steepness characteristics of columns of RC exposed to re and exposed to stress on two opposite sides.

Materials And Manufacturing
The optimum RC mixing proportion is shown in table (1), which was selected for the production of RC with speci c compressive strength following multiple test mixes and ensuring workability for compliance with the ASTM C1437-15 requirement [9]. For this study [20], products that cast off included cement [18], sand, gravel [19], steel enhancement and traditional water processing with concrete admixtures (superplasticizer's) were used [20].

Column Mould and Strengthening Column Steel Bars
The mold was arranged from plywood with internal dimensions (100 to100 to 11000) mm in order to cast

Testing procedures
The re experiments were performed by casting off a furnace made Refractive brick and refractive mother in size (15000 = 1500/1250 µm) of 250 mm wall thickness. The combination comprises four lique ed petrol gas burners on each side of the re to spread the re equally over the column length.. (2). The gas control unit and the heating pads were connected to a wireless gas gage in order to monitor the gas discharge, to maintain a constant ring temperature at a target temperature set in the digital gage prior to starting the re test. The furnaces are a metal steel structure made of three main components, a loading frame, a ring cage with insulation caps like gure. Furnace is constructed from metals and is a steel structure. (2), by means of a lever crane, the column manually positioned in the furnace. Fire exposed columns. After exposure to ames, columns were tested with a 500-ton hydraulic loading machine and accuracy of 0,5 tons in the Concrete testing laboratory, At a temperature rate of 2 ° C / s the temperature measured slowly increased until the target temperature was surpassed by re-temperature. The test con guration and instrumentation details are shown in Fig. (3).

Load-de ection results
The displacement phenomenon under load is very important to calculate as the temperature rises to understand and assess the behavior of the re exposed column. As can be seen in the gures, the displacement increases with an increase in temperature. The de ectometer dial measurements were used to monitor Axial and sideways specimen deformation. As shown in Figuration

Conclusions Based On The Results Of The Experiment:
The ndings can be taken from the results of the parametric research discussed in the present paper using both experimental analysis for columns subjected to axial loads. 5. After concrete cracking, the deformation of high-performance cement columns increases as the strength of the concrete is increased.
6. As the re spreads, cracks spread and the cement is broken, followed by a large explosion with some local longitudinal reinforcement, particularly in high cemented columns.
7. The paper suggests a new method to calculate the degraded columns ductility index following re exposure based on their energy consumption e ciency.
Page 6/12 8. The results from the exploration analysis indicate that Containing and original rigidity decreased dramatically after re exposure, and that the re temperature rose by a higher percentage when the temperature increased between 400 and 750 ° C. 9. Additional work needs to be performed Research the after re activity of RC columns with standard re curves after re exposure at temperature levels above 750 ° C because, due to limited column dimensions, the results The re temperatures of this work are limited to up to 750 ° C. 10. The pinnacle strength of the concrete columns signi cantly increases with the compressive strength of the concrete improving the ductility, energy absorption and rigidity of the RC columns.
11. Reduce the crack size as the compressive strength of the concrete increases.
12. The overall stress in RC columns depends on the compressive strength of the concrete and the elevated temperature of the re from 400 to 750 ° C.
13. The ndings of the nal factor analysis were very consistent with the results of the experiments, the higher columns of lateral strain supported by larger bar diameters and vertical displacement were similar to those of Smaller bar diameter reinforced columns.

Declarations Declaration of interests
The authors declare that they have no known competing nancial interests or personal relationships that could have appeared to in uence the work reported in this paper.