Concept on positioning of Columns

1.

Symmetry :

Investigation of the framing plan with respect to symmetry in X direction

If we split the plan vertically half, it will look mirrored, so it is symmetric in x direction.

Investigation of the framing plan with respect to symmetry in Y direction

If we split the plan horizontally half, it will look mirrored, so it is symmetric in y direction.

Redundancy :

Investigation of the framing plan with respect to redundancy in X direction

The column in x direction are more and evenly spaced, except the top and bottom rows. So the structure is more redundant in x direction

Investigation of the framing plan with respect to redundancy in Y direction

The column in y direction are lesser but evenly spaced. So the structure is redundant but lesser than in x direction.

Bi-directional Stiffness

Investigation with respect to Bi-directional stiffness

•  
  The columns in horizontal direction are connected with straight to straight beams. This means, any lateral load (Seismic force in X-direction) passing from left end of the building will have its path straight till it reaches right end of the building. So no or less possibility of force diversion takes place.
• The columns in vertical direction are not connected with straight to straight beams. So a lateral load passing from south side of building will get diverted to east & west direction to reach next bay. There will be major force diversion take place with Seismic force in Y-direction. The framing plan is weak with respect to bi-directional stiffness in Y-direction.

Ductility

Investigation of the framing plan with respect to ductility

Prima facie , the aspect ratio of the plan clearly hints more column in X-direction compared to Y-direction.It will result in higher stiffness of the building in X-direction, which would reduce ductility in X-axis.

Moreover , the X-force will easily pass from one bay to its next due to beam alignment.Where as the Y-force will struggle to pass through.The north-south beams are arranged inZig-Zag which leads to a discontinuous bracing.

We can conclude that the given framing plan is more in Y-direction than that of in X-direction.

2.

Vertival irregularity

The building plan is large in bottom stories. The floor plans are getting reduced with increase in heights. This building offset has to be cross checked with reference to IS 1893-2016 table 6 serial number iii)

Soft Storey

The building has uncovered opening in 6th floor. As there is no occupancy or partition wall. this leads to plastic hinge formations at the column. This has to be checked and sufficiently designed.

Slopy base

The building is constructed on sloping ground at one side. This will lead to significant variations in stiffness. Few levels may be subjected to soft storey mechanisms.

3.

Open ground floor

This denotes soft storey mechanisum acting in the building.

Rooms along 2 bays seperated by an opencorridor

The bays filled with rooms will have higher mass compared to the middle bay left open for corridor.This induces mass irregularity along height uniformly.

Two short sides covered with infill walls

This means the building's left and right sides periphery is more stiffer during seismic forces.

Staircase portion at left top corner

Usually staircase and lift portion are stiffer that other parts because of concentrated concrete elements.So the staircaseportion contains more stiffness in the provided building plan.

No framing connection along Y-direction

We could see no structural beams provided along the vertical direction between columns.This makes the building more vulnerable during the North-South seismic force.

Beam connected along column minor axes

The columns are having longer dimensions in Y-direction.This means they are more stiffer along Y-direction.But the beams are running only along X-direction which would attract much lesser lateral forces and hardly transfers it.

Variation in column sizes

The internal columns are having higher size compared to exterior columns.But thsi will lead to significiant diffrent in lateral drift of columns.So the concrete floor might have suffered heavy out-of-plane shear which would led to collapse.