A question about semi-rigid and fully rigid solving

[ebasakin]

Good day guys, When we solve the structure as fully rigid, the floors are not taken into account in the building analysis and the load transfers are made directly to the columns. In the semi-rigid solution, the floors are included in the calculation and meet some force. As a matter of fact, it is more appropriate to include it in the account for flooring, but flooring cutting is very common in our country. Regardless of the new old building, gaps such as stairwells are created on the floor. For this reason, wouldn't it be more rational to solve the building as fully rigid all the time? Since the slab is loaded when we solve it as semi-rigid, in case of any slab shear, a deterioration in the load transfer of the building occurs. When we solve it fully rigid, we will eliminate this problem from the beginning. What are your thoughts on this?

 

[NYILMAZ]

Since I don't have much time, I am writing a short answer. It's not like what you wrote. In any case, the floors are loaded. A fully rigid diaphragm is an admission. In simple words, in a fully rigid diaphragm, the slabs are included in the system without bending. However, in a semi-rigid diaphragm, the slabs behave out of their planes in a lifelike manner. This causes the frame system to behave more accurately. After all, the building is analyzed as a whole. The axial force cannot be calculated in the beams when the fully rigid diaphragm is assumed. Deformations in the floor plane are neglected. Especially if you have ribbed floors in the system, the structure will not be able to show rigid behavior in both directions as you expect. The finite element model, which is created by dividing the floors into shell elements in the semi-rigid diaphragm assumption, is the static and dynamic analysis of the structure by including beams, columns, ribs, shears, foundation beams and raft foundations into the global stiffness matrix. In the model, floor masses are considered as distributed masses along the floor. In buildings with A2 and A3 irregularities, it is necessary to solve with a semi-rigid diaphragm in order to take into account the effects of bending and normal force in the floor plane. I tried to say something short, good evening. We can add tomorrow if needed.