In building analysis, floors can be modeled in two different ways. The first of these is the Fully Rigid Diaphragm Adoption , where in-plane motion is neglected, assuming that the in-plane stiffness of the slabs is very high . The second is the Semi-Rigid Diaphragm Adoption , in which slab in-plane stresses and movement can occur, taking into account the stiffness of the slabs in the analysis model . It can be selected with the image shown below in the analysis settings.
...
1- Fully Rigid diaphragm:
The rigidity of the slab; The system is accepted as a rigid diaphragm if the vertical bearing system elements designed to meet the effects of earthquakes are considerably larger than the stiffness. The difference between the center of mass and the center of rigidity causes twisting in the plan. According to Article 3.6.2.2 of TBDY , rigid diaphragm acceptance cannot be applied in buildings with A2and A3 type irregularities.
...
Applicability ( Fully Rigid Diaphragm ): It is the most appropriate method when the stiffness of the structural system elements that meet the effects of earthquake is less than the stiffness of the slab. It is a common acceptance for reinforced concrete and composite floors. Analysis needs to be simplified in order to make practical design. Often an idealized rigid diaphragm is a suitable choice to simplify the analysis.
2- Semi Rigid diaphragm:
Floor stiffness; It is an analytical model representing situations where the system is close to or equal to rigidity. Stiffness calculation is calculated depending on slab thickness, dimensions and material parameters. The semi-rigid diaphragm acceptance is the acceptance that reflects the most realistic behavior of the laying behavior in the structural analysis model. In the semi-rigid diaphragm model, floors are modeled with two dimensional finite elements (shells). Two dimensional finite elements create stresses on the shell element by their in-plane out-of-plane movement. According to this stress distribution, /wiki/spaces/2IMEI/pages/1123123680 can be made.
...