Concept on positioning of Columns

1. Observations

• Investigation of the framing plan with respect to Symmetry in X-Direction:
  • If we split the plan vertically half, it will look like a mirrored image.
  • We can conclude that the given plan is symmetric in X-Direction.

• Investigation of the framing plan with respect to Symmetry in Y-Direction:
  • If we split the plan vertically half, it will look like a mirrored image.
  • We can conclude that the given plan is symmetric in Y-Direction.

• Investigation of the framing plan with respect to Redundancy in X-Direction:
  
  • The columns in X- Directions are comparitively more and evenly spaced.
  • So the structure is more redundant in X-Direction, except the top and bottom column rows are having quite longer spans.

• Investigation of the framing plan with respect to Redundancy in Y-Direction:
  
  • The columns in Y- Directions are comparitively lesser than X-Direction and evenly spaced.
  • So the structure is redundant but lesser than that of in X-Direction.

• Investigation with respect to Bi-Directional Stiffness:
  • The columns in horizontal direction are connected with straight to straight beams.
  • This means any lateral load i.e., 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 the south side of building will get diverted to east & West direction to reach the next bay for load transfer.
  • 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 respect to Ductility:
  • Primarily, the aspect ratio of the plan clearly hints more columns in the X-Direction compared to the 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.
  • Whereas, the Y-Force will struggle to pass through.
  • The North-South beams are arranged in Zig-Zag which leads to a discontinuous bracing.
  • We can conclude that the given framing plan is more ductile in Y-Direction than that of in X-Direction.

2. Observations

• Vertical Irregularity:
  • The building plan area is large in bottom stories.
  • The Floor Plan areas are getting reduced with increase in height.
  • The building offsets has to be crosschecked with the reference to Indian Standard Code 1893-2016 Table - 6 serial number iii.

• Soft Storey:
  • The building has uncovered opening space in 6th Floor.
  • As there is no occupancy or even a Partition wall, this will lead to plastic hinge formation at the column.
  • This is with reference to IS 1893-2016 Figure - 4(A).
  • This has to be checked and sufficiently designed.

• Slopy Base:
  
  • The building is constructed on a sloping ground at one side.
  • This will lead to significant variations in the stiffness.
  • This is with reference to IS 1893-2016 Figure - 5(E).
  • Few Levels may be subjected to soft storey mechanism.

3. Observations

• Open Ground Floor:
  • This Denoted soft storey mechanism acting in the building.

• Rooms along 2 bays seperated by 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 height uniformly.

• Two short sides covered with Infill walls:
  • This mieans the building's Left and Right sides periphery is more stiffer during seismic forces especially in the North-South Direction.

• Staircase portion at Left Top corner:
  • Usually staircase and lift portions are stiffer than other parts because of concentrated concrete elements.
  • So the staircase portion contains more stiffness in the provided building plan.

• No Framing connection in 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.

• Beams connected along Column Minor Axes:
  • The columns are having longer dimension in Y-Direction. This means they are more stiffer along Y-Direction.
  • But the beams are running along X-Direction which would attract much lesser lateral forces and hardly transfers it.

• Variation in Column Sizes:
  • The internal columns are having higher sizes compared to exterior columns, this is very commong because of higher load demands.
  • But this will lead to significant difference in lateral drift of columns.
  • So the concrete floor might have suffered heavy out- of -plane shear which would lead to collapse of the structure.