See EN 1998-1, 3.2.1(5)P. It gives the threshold values for very low seismicity.
Though i dont have experience for this kind of structure, In my opinion type of structure do not decide the requirement.
Does EC8 specificaly says, when it is necesery to use earthquake loads into calculations?
Im asking couse I have an simple 15mx25m hall, wich is made of exterior concrete walls and steel roof made from primary and seconday steel profiles.
Hall has only one floor and is 7m in height.
I would probably make 48 load cases which would be arranged in load groups as per imposed load categories (for example, A category for apartments and B for offices) and then I would make the software to produce critical load combinations taking each load group as leading imposed action (for examples all A category loads would be the leading ones and all B category loads accompanying), although I would require the software to ignore load cases in particular load group which are favorable for the effect under consideration.
I (we) have been asked to make a 3D calculation model. I only have to model the geometry, the loads, combinations,.... The actual calculation and the optimalisation will be done by someone else.
The project consists of :
- 2 buildings with each 4 office levels + 8 levels with 4 appartment on each level
- "bridge" between them
Each building has a center concrete core, concrete outer/inter load-bearing walls and concrete floor slabs.
(footprint of the building is +- 22m x 22m)
The model itself isn't very difficult.
But I have a question about combining the variabel loads on the floor.
Each level has 4 "units" (office or appartement) and there are 12 levels.
Should I make
1) 1 loadcase for each unit? So I have 12 x 4 loadcases = 48 loadcases of variabel loads to make combinations of?
2) or 1 loadcase for each level = 12 loadcases to combine?
3) of 1 loadcase for each unit (all levels together) = 4 loadcases
I would think in theory, I need to make 48 loadcases. But this will give a lot of combinations.
How would you handel this?