Earthquake engineering to Eurocode 8 - No seismic member aside from wall

[Agent Coconut]

Hi all,

I have a project where part of the structural requirement is capable to withstand the earthquake based on EN1998
I have some question about it.


A) Regularity of plan/elevation
The building has 3 floor, L1, L2 and Roof
All are identically in term of layout and size(about 140m x 62m) , However, because the floor height is very high at 7.0m, a small part of the floor has an intermediate floor, forming L1A and L2A (20m x 40m)
Is the building is still considered as having regularity in plan?


B) Lateral load
The clients has clarify and instruct us based on the following assumption:-
1) The lateral stiffness of shear wall is >85% of total lateral stiffness in the building
2) The building should be designed as siesmic-resistant shear wall system, NOT a moment frame system.

From our understanding, Based on EN1998; 4.2.2(4);
1) All beams and columns are now secondary seismic member that follows design and detailing is EC1 and EC2
2) Only shear wall to be designed based on EC1, EC2 and EC8.

Here come the tricky part, how do we analysis the building?
I am thinking that we can analysis the whole building as gravity only + Wind +EHF is any, and superimposed the seismic action into the shear wall. for this purpose, the seismic action will be calculated by manual calculation and distribute to each shear wall based on the stiffness.


Anyone can advise me that appropriate method for this purpose?

 

[HTURKAK]

All are identically in term of layout and size(about 140m x 62m) , However, because the floor height is very high at 7.0m, a small part of the floor has an intermediate floor, forming L1A and L2A (20m x 40m)
Is the building is still considered as having regularity in plan?

Yes . Irregular in plan and elevation . You may provide more details to get better responds.The size of the bldg (140m x 62m) seems large for a single block needs to be divided with EJ's

Here come the tricky part, how do we analysis the building?
I am thinking that we can analysis the whole building as gravity only + Wind +EHF is any, and superimposed the seismic action into the shear wall. for this purpose, the seismic action will be calculated by manual calculation and distribute to each shear wall based on the stiffness

You could develop two models . In the first model , the gravity columns and beams can be modelled with assigning pin connections at top and bottom joints or set bending stiffness to zero.. The primary SFRS shall be designed for the effects found with this comb.

The second model, delete pin connections and run again for gravity loading .Secondary elements shall be designed for this loading and for the displacements found at first comb.