Concept on positioning of Columns

Comment on the layout of the framing plan concerning earthquake resistance in the two horizontal directions X or Y (dots are columns, lines depict beams). Look into aspects of symmetry, redundancy and bi-directional stiffness and ductility.

• Investigation of the framingplan with respect to Symmetry  in X direction

If we split the Plan vertically half,It will look mirrored.So we conclude the given plan is symmetric in X direction

• Investigation of the framingplan with respect to Symmetry  in Y direction

If we split the Plan horizontally  half,It will look mirrored.So we conclude the given plan is symmetric in Y direction

Question 2:

What are the possible sources of irregularity in the building shown here? Explain how, as an engineer, each of these irregularities should be dealt with.

• Vertical Irregularity : The building plan area is large in botto stories.The floor plan area is gettimg reduced with increase in height.The building offsets had to be cross checked withreference to IS 1893 20016
• Is 1893 2016
• 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 hinges formation at the columns .This has to be checked and sufficiently designed
• Slopy base : The building is onstructed in a sloping ground at one side This will lead to significant variatons in the stiffness 

Question 3:

A 4-storey hotel building has an open ground floor for the restaurant. Story 2 to 4 have one row of rooms along each long side in plan, separated by a corridor. The two short sides of the perimeter are fully in-filled in all storeys, except for certain openings at the ends of the corridor at storeys 2 to 4 and along the right-hand side of the ground floor. There is a staircase near the upper left-hand corner, with straight flights between landings at floor levels and in-between floors. Cross-section dimensions are written next to the member no. in meters.

Comment on the features of the structural design and of the layout of infills which are important for earthquake resistance and seismic performance. How do they relate to the almost full collapse of this building (the extreme left-hand bay with the staircase survived, as well as one long-side façade in the rear end, and the frame along the right-hand side in plan).

• Open ground floor : This denotes soft storey mechanism acting on the building
• Rooms along two bays seperated by an open corridor : The bays filled with rooms will have  higher mass compared to the middle bay open or corridor. This induces mass irregularity along height uniformity.
• Two short sides covered wih infill walls : This means the building's left and right sides periphery is more stiffer during seismic forces .
• Stair case portion at left top corner : Usually stair case and lift portions are stiffer than other parts because of concentrated concrete elements . So the stair case portion contains more stiffness in the provided building plan.