Question:
I have a question about the results of the serviceability limit state design: How is the increment of the dead load by the factor of 1.8 and the imposed load by 1.48 explained in the result combinations for the SLS design?
Answer:
These increments result from the creep components in a quasi-permanent combination. You can find the overview of which combinations are to be analyzed in the serviceability limit state according to DIN EN 1995‑1‑1 here or in the links of the FAQ.
The creep components are then simply added to the characteristic deformation; for example, with 0.8 × self-weight. This results in the factor of 1.8 (see also Section 2.2.3 in EN 1995‑1‑1).
In this specific case, the following coefficients must be applied for the quasi-permanent design situation:
G-k ⋅ (1 + 0.8) + Q-k ⋅ (1 + 0.6 ⋅ 0.8) = G-k ⋅ 1.8 + Q-k ⋅ 1.48