Concept on positioning of Columns

Q1

Answer

• Checking the symmetry in X direction

If we see closely we can see the plan in X direction is mirror, if we cut the section from between hence its symmetry in X direction.

• Checking the symmetry Y direction.

If we see closely we can see the plan in Y direction is mirror, if we cut the section from between hence its symmetry in Y direction.

• Checking redundancy in X Direction.

The column in this direction is evenly spaced hence the section is more redundant in X direction.

• Checking redundancy in Y Direction.

The columns in Y direction is not evenly placed hence its less redundant then X direction.

• Bi- directional stiffness

The columns in the horizontal direction is placed such that all the column is connected to the beam in straight fashion, so any lateral force passing in this direction will have straight passage, without any diversions.

While in vertical direction columns are placed such that its not connected to beam, hence the force have to take diversion hence we can conclude that the framing is weak W.r.t to bi directional stiffness along Y direction.

• Ductility of this Frame.

We can see that there are more columns in X direction, than that in Y hence the ductility will be less in X direction.

The force has passage to pass via good connection i.e beam in X direction as compared to Y direction hence Y direction will be more ductile.

Q2

Answer

• Vertical irregularity

The building plan area is larger in Bottom stories while getting reduce as we go up, this need to be checked using IS 1983 - 2016 Table 6 serial iii

• Soft storey

The building has opening space in 6th floor, with no walls or occupancy this will lead to plastic hinge formation at column this need to checked in design With ref of IS 1983 - 2016 Fig 4A

• Slopy base

The building is constructed on sloppy base on one side this will lead to variation in stiffness ref IS 1983 - 2016 Fig 5E.

Q3

Answer

• Open GF

In question it says ground floor is open, this can lead to soft storey in structure.

• Room along 2 bay is separated by corridor

The bay having room will have higher mass as compared to bay open for corridor this induced mass irregularity over height unformily.

• 2 short side covered with infill walls.

This means building on the left and right side is more stiffer during Earthquake force.

• Staircase portion at left top corner

Generally staircase and lift portion is more stiffer as compared to othet part due to conc of concerte.

• No framing connection in Y direction

In plan we can see that beams are not connected in Y direction, which leads to failure of this structure in this direction if seismic force occure in Y direction.

• Beams connected along column minor axis

The column have longer dimension in Y direction but the beams are connected in Minor acesss, which will lead to no transfer of load.

• Size of columns

The interior columns have higher size as compared to exterior side, which is common but this will lead to lateral drift in columns, the concerte floor suffered heavy out of plane shear led to collapse.