This 2 storey building's layout is attached in the attachments. Here the architect wants to remove the column C (in the ground floor) and add a wall only from C to D. So this wall exist in the ground floor only. Based on this information, how do we check the torsional vulnerability for the whole building based on the center of resistance?
Torsion in a building is generated if the center of mass and the center of rigidity (or resistance) do not coincide. The distance between these two points is the torsion eccentricity. The center of mass is usually the geometric center (of a floor considered as a rigid diaphragm), whereas the center of resistance depends on the stiffness characteristics of the components supporting the floor (frames, shear walls, etc.).
By adding a shear wall at the ground floor, the center of rigidity is shifted considerably towards the column C. So the torsional effects will be more intense at the ceiling of the ground floor. Torsional moments will be distributed to the shear wall along CD in x axis, which will undertake most torsional distress. However, along axis y there is not any relatively stiff component to undertake the torsional moment, and therefore the ground floor will be vulnerable along this direction.
If the shear wall along CD is necessary, then an analogous shear wall has to be constructed along the y axis of the ground floor.
I hope this helps,
George
Torsion in a building is generated if the center of mass and the center of rigidity (or resistance) do not coincide. The distance between these two points is the torsion eccentricity. The center of mass is usually the geometric center (of a floor considered as a rigid diaphragm), whereas the center of resistance depends on the stiffness characteristics of the components supporting the floor (frames, shear walls, etc.).
By adding a shear wall at the ground floor, the center of rigidity is shifted considerably towards the column C. So the torsional effects will be more intense at the ceiling of the ground floor. Torsional moments will be distributed to the shear wall along CD in x axis, which will undertake most torsional distress. However, along axis y there is not any relatively stiff component to undertake the torsional moment, and therefore the ground floor will be vulnerable along this direction.
If the shear wall along CD is necessary, then an analogous shear wall has to be constructed along the y axis of the ground floor.
I hope this helps,
George
The idea to build another wall in order to minimize the torsional effects on the building suggested by George is pretty good. But i think its better to construct it in the same direction (along x axis) at the opposite side of building (see pic). In this way the center of mass and the center of rigidity will be rather close to each other.
To check the vulnerability, model the structure in a software with the proposed shear wall and find the mode shapes. Some codes do not permit torsional mode to be present in lower mode shapes.
- Badges
- Science topic
- Similar topics
- Engineering
- Civil Engineering
- Construction