Concept on positioning of Columns

1

Investigation of plan with respect to Symmetry in X direction

If we split the plan vertically half , it will look like mirrored. so the given plan is symmetry in x direction

Investigation of plan with respect to Symmetry in Y direction

If we split the plan horizontally half , it will look like mirrored. so the given plan is symmetry in Y direction

Investigation of framing of plan with respect to redundancy in X direction

so the structure is more redundant but in the top and bottom rows have bit longer spam so less redundant

Investigation of framing of plan with respect to redundancy in Y direction

The coloumns in Y direction less but evenly spaced it is also redundant but less compared to X

Investigation with respect to Bi directional stiffness

If we see the coloumns in the horizontal direction they are connected to straight beam from start to end

If the seismic force is in X direction the force will be in the straight path from left end to the right end of the building so there is less possibility of force diversion

In the vertical direction the coloumns are not connected in the straight direction with beams

So if the lateral load passing from one direction it diversifies into two here the major diversion takes place so weak in bi directional stiffness

Investigation with respect to ductility

It is inverse of bi directional stiffness

The plan clearly depicts that coloumns in X direction has more than in Y direction. So it reduces ductility in X axis

And the force also passes easily in X direction but struggles to pass in Y direction because they are arranged in the zig zag manner and leads to discontinues bracing

We can conclude that Y direction is more ductile than X direction

2

Irregularities in the building

1. Vertical irregularity-

The bottom floor area is more when compared to top as we see in the fig

The area is getting reduced with increase the height of building so the offset is checked according to respective codes

2.Soft storey

In the 6th floor as we see it is uncovered and opened and didnt even have braces or partitions which lead to plastic hinge formation at coloumns

3.Slopy base

As we see the entire building is constructed on a slopy embankment this may lead to significant variotion in stiffness and few storire may led to soft storey

(IS 1893 2016)

3

Causes of failures

Open ground floor

As it mentioned ground floor which causes soft storey failure

Rooms along 2 bays seperated by open corridor

As it mentioned top and bottom floor has room and middle floor is open for corridor which is very les mass when compared to top and bottom floors which lead to huge ass irregularity

Two short sides covered with infill walls

The two sides are filled with walls whichever they might be but they are stiff compared to the other sides

Stair case at top left corner

Where there is a staircase there is large amount of concrete and reinforcement present so there is lot of stiffness at that particular portion

No framing connection along

This might be the most significant reason for the failure of the structure

Because there are just two beams are connected in the Y direction

This leads more vulnerable to the structure in the seismic forces

Beams connected along coloumns minor axis

The coloumns are having longer dimension in Y axis so more stiffer in Y direction

But the beams are running only along X direction which would attract less lateral forces and hardly transfers it

Variation of coloumn sizes

Coloumn sizes in the middle are larger compared to corner coloumns it is correct but

This leads to significant difference in lateral drift of coloumns. So the concrete floor might suffer heavy out of plane shear which couls lead to collapse