Conceptual design of a building with columns and shear walls
1)
Aim: To Compare the above three alternatives, taking into account the restraint of floor shrinkage, the lateral stiffness
and the torsional one with respect to the vertical axis, the vertical reinforcement required for the same total flexural
capacity at the base, the static eccentricity, the system’s redundancy, foundation systems, architectural constraints
etc.
We know that when a structure is more restrained,the more will be its shrinking ,expanding and cracking.
Floor shrinkage and expanding can be observed more in structture A. In structures B and C,less cracks can
be observed.It is also decided by the shear walls in a structure whether the floor vibration is high or low.
It would be beneficial if the columns are provided at the columns rather than providing shear walls at the corners.
The important advantage of this type of arrangement is that it would reduce the formation of cracks in the
structure.
An eccentricity is observed in section C and this is the reason why the structure C has more Torsion when
compared to the structures A and B. And when we look at redundancy ,it will be more for the structures A
and B as compared to the structure C, as the structure C has an eccentricity in the left side.
If we compare the lateral stiffness, we can say that the structure C is more stiff laterally when compared to the
structure A and structure B. The reason behind it is again the same,i.e,structure C has eccentricity in the left side
where a wall of length 10m can be not able to with stand the loads.
2)
We can notice that there is a 2-way eccentricity in the given frame both in X dirction and Y direction. The
eccentricity is larger in X direction than that in Y direction. We can clearly observe in the given structure
that there are only two continuous frames i.e, B1 and B2 in the direction of X-axis and B9,B10 and B11,B12 in
the direction of Y-axis. And the remaining all the beams are observed to be broken at the midway in the frame.
One can notice that there will be Torsional flexibility in the given structure. In order to avoid the torsional
restraints, make the dimensions of the room even in both X and Y direction and to place the columns at the
junction of two walls. Providing shear walls at required locations is a good thing if it is possible.
The fundamental translational mode of vibration is larger than the fundamental torsional mode of vibration.
3)
We can say that ,the above plane is completely not suitable for normal areas and also the earthquake prone areas.
The lateral loads and vertical loads play an important role in seismic region as they assist in resisting the failure
against the earthquakes as the loads. Here, the resultant of loads wil not co-inside with the center of mass of the
structure and hence it becomes eccentric and that is why it is not suitable whatever may be the area.
Considering the above mentioned plan, it is beneficial to provide a flat slab rather than a regular beam-column
junction. The advantage of providing this type of arrangement is that ,it provides support to the column
without any provision of the beam. This greatly reduces the weight of the buiding and it also assists in the
ductility point of view which indirectly is a good thing that it also assists in maintaining the structure in the
earthquake prone areas. Instead of providing a flat slab, a wooden structure is highly recommended as it also
reduces the weight of the building and one more benefit is that it helps in maintaining the structure in the
earthquake prone areas.