# Deflection checks (SLS) (Composite beams: EC4 Eurocode)

Tekla Structural Designercalculates relative deflections. (see: Deflection checks).

The composite stage deflections are calculated in one of two ways depending upon the previous and expected future load history:

- the deflections due to all loads in the Slab dry loadcase and the
self-weight of the beam are calculated based on the inertia of the steel
beam alone (these deflections are not modified for the effects of partial
interaction).Note: It is the Slab dry deflection alone which is compared with the limit, if any, specified for the Slab loadcase deflection.
- the deflections for all loads in the other loadcases of the Design
combination will be based on the inertia of the composite section allowing
for the proportions of the particular load that are long or short term (see
above). When necessary these will be modified to include the effects of
partial interaction.Note: Tekla Structural Designerreports the deflection due to imposed loads alone (allowing for long and short term effects). It also reports the deflection for the SLAB loadcase, as this is useful for pre-cambering the beam. The beam Self-weight, Dead and Total deflections are also given to allow you to be sure that no component of the deflection is excessive.Note: Adjustment to deflections. If web openings have been defined, the calculated deflections are adjusted accordingly. See: Web Openings