Section properties - serviceability limit state (SLS) (Composite beams: BS 5950)
BS 5950-3.1:1990+A1:2010 indicates that the Serviceability Limit State modular ratio for all SLS calculations should be based upon an effective modular ratio derived from the proportions of long term loading in the design combination being considered.
Tekla Structural Designer therefore calculates the deflection for the beam based on the properties as tabulated below.
| Loadcase type | Properties used |
|---|---|
| self-weight | bare beam |
| Slab | bare beam |
| Dead | composite properties calculated using the modular ratio for long term loads |
| Live | composite properties calculated using the effective modular ratio appropriate to the long term load percentage for each load. The deflections for all loads in the loadcase are calculated using the principle of superposition. |
| Wind | composite properties calculated using the modular ratio for short term loads |
| Total loads | these are calculated from the individual loadcase loads as detailed above again using the principle of superposition |