Concept on positioning of Columns

Ans 1: The observations are as follows:

Symmetry:

• Investigation of the framing plan with respect to symmetry in X-direction: If we split the plan vertically half, we get a mirror shaped plan. So we conclude the given plan is symmetric in X-direction.
• Investigation of the framing plan with respect to symmetry in Y-direction: If we the plan horizontally half, we get mirror shaped plan. So we conclude the given plan to be symmetry in Y-direction.

Redundancy:

• Investigation of the 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 redundant in X-direction' Except the top and bottom rows which are longer spans.
• Investigation of the framing plan with respect to redundancy in Y-direction: The columns in Y-direction are comparetively lesser but evenly spaced So the structure is redundant but lesser than that of x-direction.

Bi-Directional Stiffness:

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

Ductility:

• As there is more Columns in X-direction compared to Y-direction. It will result in higher stiffness of the building in X-direction, which would result in less ductility in X-direction.
• The X-force will easily pass from one bay to its next due to beam alignment. Whereas, the Y-force will strugle to pass through. The north-south beams are arranged in zig-zag which leads to a discontineous bracing.
• We conclude that the given framing plan is more ductile in Y-direction than that of in X-direction.

Ans 2: The Observations are below:

• Vertical Irregularity: The building plan are is higher in bottom stories. The Floor plan are are getting reduced with increase in height. These building offset has to be crosschecked with refference to IS-1893-2016 Table-6 serial no. 3
• Soft Storey: The Building has uncovered opening space in 6th floor. As there is no occupancy or a partition wall, this will lead to plastic hinge formation at the columns, this had to be checked and sufficiently designed.
• Slopy Base: The Building is constructed on as Sloping Ground at one side. This will lead to significant variations in the stiffness. Few levels may be subjected to soft storey mechanism, it should be checked with IS 1893-2016 Figure 5E.

Ans 3: The Observations are below:

• 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 room will have higher mass compared to the middle bay left open for corridor. This induces mass irregularity along height uniformity.
• Two Shorts sides covered with infill walls: This means Building's left and right sides periphery is more stiffer during sesmic force.
• Staircase portion at left top corner: Usually staircase and lift portion 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 along Y-direction: We could see no structural beams provided along the vertical direction between columns. This makes the building more vernerable during North-South sesmic forces.
• Beams connected along column minor axis: The columns are having longer dimension 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 transfer it.
• Variation in column sizes: The Internal columns are having higher sizes compared to the exterior columns. 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.