The calculation is based on a linear deflection from permanent loads (or prestressing) applied in construction stages. The calculation will be performed after clicking the Auto button (the value can still be defined manually).

The effective time *d* is calculated according to the formula:

*\[d = \frac{{\sum\limits_{n = 1}^i {{t_i}\cdot\,{u_{st,i}}} }}{{\sum\limits_{n = 1}^i {{u_{st,i}}} }}\]*

where

*t** _{i }* time when the load (or prestressing) for each phase is applied

*u** _{st,i }* the absolute value of the maximum short-term linear deflection from the applied load (or prestressing)

The particular times used when the load is applied can be found in the construction stage tab, whereby the Superimposed dead load is the last phase taken into account. The used value of the linear deflection has been calculated by the software. For the construction stage in which we apply prestressing, we consider both values in the calculation - from the permanent load and from prestressing.

Available in both **Expert** and **Enhanced** editions of IDEA StatiCa Concrete and Prestressing.