Calculate Long-Term Factors

The Calculate Long Term Factors button in the Combinations window, allows you to calculate load factors for all ‘auto” long-term combinations (Deflection Load Type is set to Auto). The calculation of the factors is based on the method specified in the Long-Term Deflection Settings window (Criteria, Long-Term Settings).

To create an "auto" calculate Long-Term load combination:

1. Display the Deflection Load Type, Age at Loading and Observation day columns.

   1. Click on Choose to open the Filter window.

      

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   2. Check the Type, Age at Loading and Observation Day checkbox.

   3. Click OK.

      Tip:

      In lieu of these steps, you can click the Deflection button.

      

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2. (Required) Add the "sustained" load combination:

   1. Click the + button to add a new load combination. By default the combination will have its Analysis/Design option set to "Service Sustained Load"

   2. Name the new combination as you see fit. In the example below we use "Sustained_Load".

   3. Click in the Analysis/Design option cell in the row for this newly created combination and choose CRACKED DEFLECTION from the menu.

      

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   4. Click in the Deflection Load Type cell and choose Sustained from the menu.

      

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   5. Enter the Age at Loading number of days.

      This should not be less than 7 days for moist cured, or 3 days for steam cured concrete, when Detailed Method is selected in the Long-Term Deflection Settings window.

      

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   6. Repeat these steps if you want to enter multiple sustained load combinations, with each representing a different loading stage.

3. (Optional) Add the "total" load combination:

   1. Click the + button to add a new load combination. By default the combination will have its Analysis/Design option set to "Service Sustained Load"

   2. Name the new combination as you see fit. In the example below we use "Total Load".

   3. Click in the Analysis/Design option cell in the row for this newly created combination and choose CRACKED DEFLECTION from the menu.

      

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   4. Click on Deflection Load Type and choose Total.

      

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4. Add the "long-term" load combination:

   1. Click the + button to add a new load combination. By default the combination will have its Analysis/Design option set to "Service Sustained Load"

   2. Name the new combination as you see fit. In the example below we use "Long_Term1".

   3. Click in the Analysis/Design option cell in the row for this newly created combination and choose Long-Term Deflection from the menu.

      

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      The red Label text indicates that the factors have not been calculated yet.

   4. Click in the Deflection Load Type cell and choose Auto (if not already selected).

      

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   5. Enter the Observation day value.

      

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   6. Enter the load factors.

      Use 1 or any other number, in the cells for the sustained and total load combinations that you previously defined and want to include in the long-term combination.

      Note: You can include only one "total" load combination.

      

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5. Click the Calculate Long-Term Factors button at the bottom left corner of the Combinations window.

   The program overwrites the factors you entered with the calculated values based on the calculation method specified in Long Term Deflection Settings (Criteria, Long Term Settings button).

   

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   See TN600_Calculation of Factors for Long-Term Load Combinations for an explanation of how the factors are calculated.