Perimeter Column Temperature Curves
Next, we must define the temperature growth profile in the perimeter columns. These often have a slower temperature increase because they are shielded from the fire or are external to the building envelope. This must be reflected in their time-temperature curve.
In this case the perimeter columns are external to the envelope and are unprotected. The maximum temperature of the perimeter columns was determined to be 688 degrees using the 'Law and O'Brien' external steelwork calculations. The temperature rise is based on a burn-out period of 20 minutes with a linear increase from 20 degrees up to this plateau.
To do this:
1. Open the "Properties | Temperature Curves" dialog box.
2. Select the 'Add' tab. A new curve (curve '5') is automatically generated.
3. In the 'Type' drop-down box, select the 'trom file' option. Browse for the 'Perimeter_Column.txt' temperature curve and open this.
4. Click the 'Add' button to place the curve on to the database for this example.
5. Select the 'Attach' tab and curve 5 from the drop-down menu. Choose the 'Attach to beams' option and click those beams that require to be protected.
6. Click the 'Attach' button.