Concept on positioning of Columns

1. Investigation of the frame plan with respect to symmetry in x- direction:

if we split the plan horizontally half , it will look mirrored . so we conclude the given plan is symmetric in x- direction.

Investigation of the frame plan with respect to symmetry in y- direction:

if we split the plan vertically half , it will look mirrored . so we conclude the given plan is symmetric in y- direction.

Investigation of the frame plan with respect to redundancy in x direction:

the columns in x -direction are comparatively more and evenly spaced. so the structure is more redundant in x-direction. Except

the top and bottom columns rows are having quite longer spans

Investigation of the frame plan with respect to redundancy in x direction:

the columns in y-direction are comparatively lesser but evenly spaced. so the structure is redundant but lesser than in x-direction.

Investigation with respect to bi-directional stiffness:

The columns in horizontal direction are connected with the 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 less possibility of force diversion takes place.

The columns in vertical direction are not connected with the straight to straight beams. This means , any lateral load (Seismic force in y-direction ) passing from south side of the 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.

Investigation of the framing plan with repect to ductility:

prima facie, the aspect ratio of the plan clearly hints more column in x-direction compared to y-direction. It results in higher stiffness of the building in x-direction, which would reduce ductility in x-axis.

more over, the x-force will easily pass from one bay to its next due to beam alignment. whereas, th e y-force will struggle to pass through. The north-south beams are arranged in zig -zag which leads to discontinous bracing.

we can conclude that the given framing plan is more ductile in y direction than that of in x-direction.

2. Vertical irregularity: The building plan area is large in bottom stories. The floor plan area are getting reduced with the increase in height. These building offsets has to be crosschecked with reference to IS 1893 -2016 table 6 serial 3

soft storey: The building has uncovered opening space in 6 th floor .As there is no occupancy or partition wall , this will lead to plastic hinge formation at the columns ( with reference to IS 1893-2016 figure 4A). This has to checked and sufficiently designed.

slopy base: The building is constructed on a sloppy ground at one side. This will lead to significant variation in stiffness ( with reference to IS 1893-2016 figure 5E).Few levels may be subjected to soft storey mechanism.

3. Open ground floor: This denotes soft storey mechanism acting in the building.

Rooms along 2 bays separated by an open corridor: The bays filled with rooms will have higher mass compared to the middle bay left open for corridor.This induces mass irregularity along the height uniformity.

Two short sides covered with infill walls: This means the building left and right sides periphery is more stiffer during seismic forces( especially alond Nortn-south).

staircases portion at the left top corner: Usually staircase and lift portions are stiifer than other parts because of concentrated concrete elements. So staircase portion 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 building more vulnerable during north-south seismic force.

Beams connected along column minor axes - The columns are having longer dimensions in y-direction. This means there are more stiffrer along y-direction. But beams are running only along x-direction which would attract lesser lateral forces and hardly transfers it.

variation in column sizes: The internal column sizes are having higher sizes compared to exterior columns( this is common because of higher load demands) . But this will lead to significant difference in lateral drift of columns. So concrete floor might have suffered heavy out of plane shear which would lead to collapse.