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.

Ans :

symmetry

• The given frame with respect to symmetry on the both X and Y direction .
• If we cut the half frame in the x direction then it shows the mirror right of the frame
• If we cut the half frame in the y direction then it shows the mirror right of the frame
• The column are spaced the evenly in the x direction expect top and bottom column rows having quit longer span
• The column in y direction comperatively lesser but evenly spaced so the structure is redundent but lesser thanthat of x direction .

Bi-directional stiffness

• the columns in horizontal direction or connected with straight to straight beams this means any lateral load passing from left end of the building will have its path straight till it reaches the right end of the building so now or less possibility of first diversion takes place
• the columns in vertical direction are not connected with straight to straight beams .there will be major force diversion take place with seismic loads in y -direction . The framing plan is weak with respect to bi-directional stiffness

Redundancy:

• Structural elements in the frame is uneven distribution of earthquake action effects in nonlinear range across the frame
• the energy diserpsion is very low which result of non reliable structure .

Ductility:

• The building frame may not able to resist the earthquake forces in y direction so result it inelastic
• the reduction in design force in the y direction is to be compensted by ductility.

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.

Ans :

Vertical irregularity : Building plan area is large in bottom stories the floor plan areas are getting reduced with increasing height please building of sets has to be crosschecked with reference to IS 1893-2016 table serial number (3).

Soft storey : The building has uncovered opening space in 6th floor right as there no brazing that is no partition wall is no mass no work open says nothing so uncover opening space this will lead to a plastic information of the columns so with reference to IS 1893-2016 fig - 4A this checked and sufficently designed

Slopy base : The building is constructed on a sloping ground at one side display to a significant variations inthe stiffness with reference to IS 1893-2016 fig 5E .few levels may be subjected to sub story mechanism.

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).

Ans :

• Soft story mechansim
• irregular structure
• donot have proper infill walls
• Beams connected along the cloumn mirror axis
• the front end compared to longer end the length of the beam increases and column size also decrese it will not designed properly to bear the load
• Comparatively the column number must be incresed for the beam length or the retain wall should be proper