UK: Приведены основные сведения о разработанном методе расчетной интерпретации температурных показателей, полученных в результате испытаний железобетонных колонн на огнестойкость без приложения механической нагрузки. Исследована эффективность метода решения прочностной задачи при определении предела огнестойкости железобетонной колонны по результатам огневых испытаний.
EN: The problem. Testing the concrete columns on fire is carried out in accordance with the applicable
standards of Ukraine. According to these standards the column should be subjected to the firing action
under the condition of the column load power factors that fully meet the load in the column under the
design model of the building. These factors are created by the corresponding nodes of the testing
facilities that combine fire oven with the support-loading device. Fire oven has fireproof enclosures,
configuration that ensures evenly heating of the construction elements. It is also equipped with fuel-
nozzle system on liquid fuel that ensures standard temperature mode of fire. Mechanical load is
created by hydraulic press that ensures compressive strength up to 500 t.
The implementation of these conditions causes certain technical difficulties such as mismatch of
conditions of fixing and loading the column in the construction, mismatch of out-sample for testing
and the real column etc. That is why the standard for fire resistance test of columns does not prohibit
testing without applying mechanical stress; meanwhile the aforementioned standard does not give any
grounded methodology for determining the fire resistance of reinforced concrete columns based on
such testing. Moreover, fire test of the columns have limitations on the length of the subjected
columns, ways of their fixing, type and size of mechanical loading on the column.
Analysis of recent achievements and publications. Analysis of publications on computational
methods for designing concrete columns by their fire safety shows that the appointed methods allow to
take into account all of the listed features. Therefore the objective of the study is formulated.
Statement of the problem and its solution. The purpose of the study is to substantiate the method
of solution strength problem to assess the fire resistance of reinforced concrete columns with
rectangular cross section calculated on the basis of the interpretation of the results of fire tests.
The method of determination of actual fire resistance of reinforced concrete columns is given in
the article. The stated method is based on the calculation interpretation of fire tests without applying
mechanical stress.
To achieve this goal it is necessary to solve the problem of restoration of temperature fields in the
cross section of the column by results of point temperature measurement in the inner layers. The
methodology of the problem solution is described in the article. Under the terms of the implementation
of the developed methods it is necessary to interpolate the results of measurements of temperature in
the control points section of reinforced concrete columns. For testing procedures of fire assessment
methods by interpreting the results of fire tests appointed testing of two reinforced concrete columns
500 Ч 500 Ч 3 000 from heavy concrete was conducted on granite filler in the fire oven.
Conclusions. As a result of the research the following conclusions can be made.
1. Fire testing of reinforced concrete columns was conducted. On the basis of this testing the
stability of interpolation methods was investigated. Therefore the most effective method of
interpolation was selected. The method is based on approximation of field isotherms.
2. The sequence of procedures of strength calculation method on the basis of temperature
measurement in the inner layers of the reinforced concrete column during fire testing was grounded.
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3. The limit of fire resistance of reinforced concrete columns was determined on the basis of
interpretation of the data obtained during the fire tests using the proposed method of calculating
strength.
