Concept on positioning of Columns

1.

Answer:- 

Investigation of framing plan with respect to redundancy in x- direction

• The columns in x- direction are comparitively more and evenly spaced 
• So the structure is more redundance in x- direction
• Except top and bottom column rows are having quite larger span

Investigation of framing plan with respect to redundancy in x- direction

• The columns in y- direction are comparitively less but evenly spaced
• So the structure is redundant but lesser than that of in y- direction

Investigation with respect to the bidirectional stiffness

• The column in horrizontal direction are connected with straight to straight beams.
• This means any lateral load passing from the left end of the building will have it's path straight till kit reaches right end of the building
• So no or less posssibility of force diversion takes place

• The column in vertical- direction are not connected to the straight to straight beams
• So the lateral load passing from the south side of the building will get diverted to the east and west direction to reach next bay
• There will be majour force takes place with seismic force in y- direction
• The framing plan is weak with respect to bi-directional stiffenss in y- direction 

Investigation of framing plan wirh respect to ductility

• Prima facie, the aspect ratio of the plan clearly hints more column in x- direction comapred to y- direction
• It will result higher stiffness of the buiding in x- direction, which would reduce ductility of the building in x- direction

• More over the x- force will easily from one bay to its next due to beam alignment
• Where as y- force will struggle to pass through
• The north-south beam arranged in zigzag which leads to discontinuous bracing 

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

2.

Answer:- 

Vertical irregularity

• The building plan is larger in bottom stories. The floor plan area getting reduced with increase in height
• The building offset has to be cross checked with reference to IS 1893-2016 table 6 serial number 3

Soft storey

• The building has uncovered opening in 6th floor. As there is no occupancy or partition wall
• This will leads to plastic hinge at  the column (withreference to IS 1893-2016 figure 4A). This has to be checkedd and sufficiently designed

Slopy base

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

3.

Answers:-

Open ground floor 

• This denotes soft storey mechanism acting in the buiding

Rooms along 2 bays seperated by an open corridor

• The bays filled with rooms will have higher mass compared to the middle bay left open corridor
• This induced mass irregularity along height uniformity

Two short sides covered with infill walls

• This means the buildng left and right sides periphery is more stiffer during seismic forces (especially along North- South)

Staircase portion at left top corner

• Usually the staircase and lift portion are stiffer than the other parts because the concentrated concrete elements
• So the staircase portion contains more stiffness in the provided building plan

No framing connections along Y-direction

• We could see no structural beams provided along the vertical direction between the column 
• This makes the building vulnerable during the North - South building force

Beams connected along column minor axis

• The columns are having longer dimension in Y- direction. This means they are 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 size

• The internal column are having higher sizes comapred to the exterior column (This is common because of higher load demands)
• But this will leads to significant difference in lateral drift of columns
• So the concrete floor might have suffered heavy out of plane shear which would led to collapse