Introduction

The crack width is calculated according to clause 7.3.4 in EN 1992-1-1. The decompression check is calculated based on 7.3.1(5) in EN 1992-1-1. The following preconditions are used for calculation :

• The crack width is calculated for beams for general load (N + M_y + M_z)
• Cross-section with one polygon and one material is taken into account in version SCIA Engineer 20
• The material of all reinforcement bars have to be same in SCIA Engineer 20
• Normal stress on un-cracked section at the most tensioned fibre for determination if crack occurred or not (check of normal stresses), should be calculated for characteristic combination of the load according to EN 1992-1-1, clause 7.2(2).

SCIA Engineer automatically use characteristic or quasi-permanent combination together in one step. Regardless on what combination (Characteristics, Quasi-permanent of Frequent) is selected.

Selected combination is used as place holder for Load Cases, where appropriate coefficients are used during check (Characteristics, Quasi-permanent of Frequent). Recommended is to use the Result class with all SLS combinations from the project, or combination with all Load Cases.

Characteristic combination is used for evaluation if cracks appear.

Quasi-permanent combination is used for calculation of crack width.

If national annex use Frequent combination instead of Quasi-permanent for calculation of crack width, than SCIA Engineer automatically use Frequent combination.