Concept on positioning of Columns

ANSWER NO 1

AIM :

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.

ANS:

if we are Investigation of the framing plan with respect to the X-direction then we are found many result ;

• If we split the plan vertically half, it will look mirrored. So we conclude the given plan is symmetric in X-direction.
• The columns in x-direction are comparatively more and evenly spaced. So the structure is more redundant in x-direction.
• The columns in horizontal direction are connected with straight to straight beams. This means, any lateral load (Seismic force in X-direction) passing from left end of the building will have its path straight till it reaches right end of the building. So no or less possibility of force diversion takes place.
• The given framing plan is low ductility in x- Direction.

if we are Investigation of the framing plan with respect to the Y-direction then we are found many result ;

• If we split the plan horizontally half, it will look mirrored. So we conclude the given plan is symmetric in Y-direction.
• The columns in y-direction are comparatively lesser but evenly spaced. So the structure is redundant but lesser than that of in x-direction.
• The columns in vertical direction are not connected with straight to straight beams. So a lateral load passing from south side of building will get diverted to east & west direction to reach next bay. 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.
• The given framing plan is high ductility in y- Direction.

ANSWER NO 2

AIM :

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.

ANS:

The possible sources of irregularity in the building as an engineer are :

• Vertical irregularity according to IS-1893-2016.
• Soft storey according to IS-1893-2016
• STIFFNESS IRREGULARITY (SOFT STOREY) according to IS-1893-2016

Answer no 3

AIM :

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).

ANS:

• The Open ground floor are denotes soft storey mechanism acting in the building.
• 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.
• Two short sides covered with infill walls - This means the building's left and right sides periphery is more stiffer during seismic forces (especially along North-south)
• Staircase portion at Left top corner - Usually staircase and lift portions are stifferthan other parts because of concentrated concrete elements. So the staircase portion contains more stiffness in the provided building plan.
• No framing connection along Y-direction.