Control clause 10-3 of standard 2800 for the components of the structure that are not part of the lateral bearing system.
The most common use of this clause is in flat slab systems. Suppose that in a flat slab system where the columns are designed only for gravity loads, the elastic displacement is 5cm, but the non-linear displacement is 25cm. In reality, this column moves 25cm along with the ceiling, and I did not see the effect of this change anywhere in the structure, so we actually want to apply non-linear deformations of the structure to the columns and check if they will respond to the change of location. No, a column that is only attached to the diaphragm at one point. well
For this, I need to create a check file, and in this file, the columns and walls must have their original hardness (if they are cracked or not, their respective coefficients). What should I do now??
A) C × Cd
I have to make the earthquake coefficient C equal to d index
I will read the delta center mass of the roof floor, for example, the number is 12 cm, I also have the cd factor and multiply it to 60 cm, I will call this number delta 1
Then I come to the check file, I read the delta of that roof floor and name it delta2, with the difference that my earthquake force is equal to cd
I write these numbers in a corner and keep it.
I said that the displacement of my center mass was 12 cm, which cd equaled to 60 cm, non-linear displacement, which means that I should have a displacement of 60 cm on the roof floor.
Now I have to calculate a new earthquake coefficient, how?
C new = c × (delta1/delta2) or (delta2/delta1)
Let’s assume that my delta 2 is 54 cm, so I have to increase this delta to 60 cm, how about you? With the increase of the earthquake coefficient, then finally should be ratio
Delta1/delta2
multiply by the earthquake coefficient I had, I check the change of location created with c new to see if it has reached 60cm, when it reaches, I design the columns for this earthquake coefficient and get the answer.
The goal is to make the non-linear displacement equal to the actual non-linear displacement of the structure, that is, the ratio
Delta1 / delta2 =1
ok This clause is easily controlled from the standard, which works most of the time in projects.
In the second method of this control, according to ACI, you can silence the columns based on special plasticity criteria.
Be successful and victorious.
Mojtaba Shiri
This post is written by MOJTABA_SHIRI