Concept on positioning of Columns

1):

Aim: To look into aspects of symmetry, redundancy and bi-directional stiffness and ductility. of the framing plan concerning earthquake resistance in the two horizontal directions X or Y.

Investigation of the framing plan W.R.T symmetric in the x- direction.

• If we split the plan vertically half it will look mirrored so we conclude the given plan is symmetric in the x direction

Investigation of the framing plan W.R.T symmetric in the y- direction.

• If we split the plan horizontally half it will look mirrored so we conclude the given plan is symmetric in the y direction

Investigation of the framing plan W.R.T redundancy in the x- direction.

• The columns in the x direction are comparatively more and evenly spaced. So the structure is more redundant in x direction. Except the top and bottom column row are having quit longer span.

Investigation of the framing plan W.R.T redundancy in the y- direction.

• The column in the y direction are comparatively less but evenly spaced. So the structure is redundant but lesser then that of in x direction.

Investigation of the framing plan W.R.T Bi-direction stiffness:

• The columns the horizontal direction are connect with straight to straight beams. This means the lateral load (seismic force In x direction) passing from the left end of the building will have its path straight till it reaches the right end of the building. So nor or less possibility of the force distribution takes place.
• The columns the vertical direction are not connect with straight to straight beams. So lateral passing from south side of the building will get diverted to east and west direction to each next bay. Ther will be a major force diversion take place with seismic force in y direction. The framing plan week with respect to bi-direction stiffness in y – direction.

Investigation of the framing plan W.R.T ductility:

• 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 could reduces ductility in x direction.
• The x direction force will easily pass from bay to its next due to beam alignment whereas the y direction struggle to pass through. The north south beams arrange in zigzag which leads to discontinue bracing.
• We can conclude that given framing plan is more ductile in y direction than that of in x direction

2):

Aim: To explain the possible sources of irregularity in the building shown.

Vertical irregularity: The building plan area is larger in bottom stories. The floor plan area are getting reduce with increase in the height. The building offset has to be cross check with reference to IS – 1893 – 2006 table 6^th serial number (iii)

Softe story: The building has uncovered opening in the 6^th floor. As there is no occupancy or partition wall this will leads to plastic hinge at the columns (with reference to IS 1983 – 2016). This has to checked and significantly design.

Slopy base: The is constructed on sloping ground at one side. There will lead to significant variation at the stiffness (with reference to IS 1983 – 2016). Some stories may be subjected to soft story mechanism.

3):

Aim: To investigate the given building structural plan & its causes of collapse after an earthquake.

Open ground floor : This denotes soft story mechanism acting on the building.

Rooms along 2 bay separated by an open corridor: The bay filled with rooms will have higher mass compared to the middle bay left open for the corridor. This include mass irregularity along height uniformly

Two short side sides covered with infill wall: This means the building left and right side periphery is more stiffer during seismic force

Staircase portion at left top corner : Usually the staircase and lift portion are stiffer then other part because of concentrated concrete elements. So the staircase portion contains more stiffness in the provided building plan.

No frame connection along Y direction : We could see no structural beams provided along the vertical direction between the columns. This makes the building more vulnerable during the north south seismic force

Beams connected along column minor axes: The columns having longer direction in the y axis. This means they are more stiffer in y direction but beams are running along x direction which could attract more lesser lateral forces and hardly transfer it.

Variation in column size: The internal column having higher size compared to exterior column this is common because of higher load demand. But this will load to significant difference in the lateral drift of the column. So the concert floor might have suffered heavy out of plan shear which would led to collapse.