Concept on positioning of Columns

1.

i)Symmetry:

Investigation of the framing plan with to symmetry in X-direction:

If we split the plan on "Vertical half" , it will look mirrored.So we conclude the given plan is symmetric in X-direction.

Investigation of the framing plan with to symmetry in Y-direction:

If we split the plan on "Horizontal half" , it will look mirrored.So we conclude the given plan is symmetric in Y-direction.

ii)Redundancy:

Investigation of the framing plan with to Redundancy in X-direction:

The column in X-direction are comparatively more and evenly spaced.So the structure is more redundant in X-direction.Except top and bottom column rows are having quite longer space.

Investigation of the framing plan with to Redundancy in Y-direction:

The column in X-direction are comparatively more and evenly spaced.So the structure is more redundant in Y-direction.

iii)Bi-directional stiffness:

• The column in horizontal direction are connected with straight beams.This means , any lateral load passing from left end of the building will have its path straight till it reaches end of the building.So no less possibility of force diversion takes place.
• The columns in vertical direction are connected with straight to straight beams.So lateral load passing from south side of the building will get diverted to east and west direction to reach next day.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.

iv)Ductility:

• Prima facie , the aspect ratio of the plan clearly hints more column in X-direction compared to 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.Where as the Y-force will struggle to pass through.The north-south beams are arranged inZig-Zag which leads to a discontinuous bracing.
• We can conclude that the given framing plan is more in Y-direction than that of in X-direction.

2.

i)Vertical irregularity:

The building plan area is large in botttom stories.The floor plan areas are getting reduce with increse in height.These building These building floor plan areas are getting reduced with increase in height.These building offset has to be crosscheked with reference to IS-1893-2016 table-6-serial number(iii).

ii)Soft storey:

The building has uncovered opening space in 6th floor .As there is no occupany or a partition wall,this lead to plastic hinge formationat the columns.This has to be checked and sufficient designed.

IS-1893-2016.

iii)Slopy base:

The building is constructed on a sloping ground at one side.This will lead to significiant variations in the stiffness.Few levels may be subjected to soft story mechanisum.IS-1892-2016.

3.

i)Open ground floor:

This denotes soft storey mechanisum acting in the building.

ii)Rooms along 2 bays seperated by an opencorridor:

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.

iii)Two short sides covered with infill walls:

This means the building's left and right sides periphery is more stiffer during seismic forces.

iv)Staircase portion at left top corner:

Usually staircase and lift portion are stiffer that other parts because of concentrated concrete elements.So the staircaseportion contains more stiffness in the provided building plan.

v)No framing connection along 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.

vi)Beam connected along column minor axes:

The columns are having longer dimensions 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 transfers it.

vii)Variation in column sizes:

The internal columns are having higher size compared to exterior columns.But thsi will lead to significiant diffrent in lateral drift of columns.So the concrete floor might have suffered heavy out-of-plane shear which would led to collapse.