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