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Temperature distribution curve

Thermal load can be defined through a distribution curve that defines the distribution of the heat across the cross-section of a member.

When a member is exposed to fire, one side of the cross-section is directly exposed to the source of the heat. The temperature to which the interior of the cross-section is exposed to decreases with the distance from the directly exposed face. The temperature distribution curve defines this drop in the temperature.

To allow for this type of load, it is necessary to select Concrete > Fire resistance option in the Project settings.

The temperature distribution curve can be defined in the Temperature curves manager. Once at least temperature curve is defined, it can be used in function Load > Thermal load.

Temperature curves manager

The Temperature curves manager is a standard SCIA Engineer database manager. You can perform the following:

input of a new temperature distribution curve,
review and modify the existing curves,
copy and delete the defined curves,
save them to an external file,
import temperature distribution curves from previously created external files (the external file can also be provided by a colleague user),
import predefined temperature distribution curve created according to the regulations of EN 1168.

Temperature distribution curves input dialogue

One temperature distribution curve defined in the Temperature curves manager may in fact consist of several individual curves. Each individual curve is defined for one time duration of fire. The final temperature distribution curve stored in the Temperature curves manager can be thus used for any duration of fire that is within the interval of durations of individual curves. If the user specified time duration coincides with one of the individual curves, then that corresponding curve is used in the calculation. If the user specified time duration is somewhere in between, the curve to be used in the calculation is automatically interpolated by the program.

$image\TemperatureCurve.gif$

Consequently, the input dialogue is a two-level input dialogue. The first level displays the whole set of defined curves. The second level enables the user to work with one particular individual curve.

It is, however, also possible that the final curve consists just of one individual curve.

First-level dialogue – the set of curves

Graphical window	This part of the dialogue displays the defined set of curves.
Name	Specifies the name of the temperature distribution curve.
Description	Describes the curve (e.g. "Temperature curves for hollow core slabs according to EN 1168").
Fire duration	The final fire duration used in the calculation. If the value specified here coincides with one of the individual curves, the corresponding curve is used. Otherwise the final curve is obtained through interpolation.
List of individual curves	Lists the defined individual curves.
[New]	Inputs a new individual curve (opens the second-level dialogue).
[Edit]	Enables the user to edit one of the already defined individual curves.
[Delete]	Deletes one of the already defined individual curves.
[Delete All]	Deletes all the already defined individual curves.
Property table	Summarises the information about the individual curve currently highlighted in the list. In addition, it enables the user to adjust the required colour of the individual curve.

Second-level dialogue – one individual curve

Graphical window	This part of the dialogue displays the defined curve.
Table	In this table you input individual points that define the curve. Distance = the distance from the face of the cross-section that exposed to fire. The distance is measured from the face inwards. Temperature = the temperature at the given distance.
File duration	Specifies the time duration of the fire.
[OK]	Saves the input and closes the dialogue.
[Cancel]	Discards the input and closes the dialogue.

The procedure to input a new temperature distribution curve

Open the Temperature curves manager:
1. Use tree menu function Library > Temperature curve.
2. Use menu function Libraries > Temperature curve.
Click button [New] to start the input of a new temperature distribution curve (if no temperature distribution curve has been defined so far, this step is automatically skipped and you are asked to input temperature distribution curve as soon as you the Temperature curves manager.
The Temperature distribution curves input dialogue is opened on the screen (i.e. the first level dialogue).
Click button [New] to input one individual curve. Confirm the input with [OK].
If required, add other individual curves.
Input the required duration of the fire. (The duration of fire can be also adjusted directly in the main dialogue of the Temperature curves manager.)
Close the Temperature distribution curves input dialogue. You get back to the Temperature curves manager.
If required, input another time distribution curve.
When everything is defined, close the manager.

The procedure to import the predefined (according to a standard) temperature distribution curve

Open the Temperature curves manager:

1. Use tree menu function Library > Temperature curve.
2. Use menu function Libraries > Temperature curve.
Click icon System database.
The Read from database dialogue is opened on the screen.
The right-hand side window contains the available predefined curves.
The left-hand side window contains the curves that are defined in the project.
Use button [Copy to project] or [Copy all] to copy the required curves into your project.
Close the dialogue.

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