Concept on positioning of Columns

 

Question 1:

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.

ANSWER -

SYMMETRY-

in symmetry process we compare 2 

indentical objects .

2 object are mirror image each 

other is called symmetrical 

 

a] symmetry in x direction -

when  we split above given plan 

along  x direction 

then it seem to identical 

-hence it is symmetrical in x direction .

 

b] SYMMETRY IN y direction -

when 

we split above given plan 

along  y direction 

then it seem to identical 

-hence it is symmetrical in y direction .

 

2.REDUNDANCY:

Redundancy  is a behaviour of 

structure arrangement ,in building 

 sufficient no. of supports which 

are arranged in order .

 

a]Redundancy in x direction -

-from the given plan , we can see 

column in  x direction more and 

evenly distributed in middle portion .

-so we  can say structure are 

redaundant in x direction .

-column arrangement top and bottom 

rows are very less while

comparing middle portion 

-but these column are evenly seprated .

 

-so we can say structure in x direction is 

redautant in nature .

 

b].Redundancy in y direction -

-when we observing  y direction 

column is lesser comparing 

comparing with x direction .

-eventhough they are lesser no. 

of column in y direction are evenly 

spread .

-we can say structure are redaundant 

in y direction .but comparing with -x 

direction lesser redundancy .

3.)BI DIRECTIONAL STIFFNESS :

 

a).Bi-Directional stiffness along

X-Direction:

 -From the given plan we can observethat

the columns in the X-directions are connected

in a straight line which is beams in a continous

manner So that the loads can be transffered

easily in the X-Direction We can conclude

that the frame is stronger in the Bi-lateral

stiffness in the X-Direction 

b).Bi-Directional stiffness along Y-Direction:

 From the given plan we can observe that

the columns in the X-directions are connected

in a straight line which is beams  not in a continous

mannerWe can see empty spaces after the

beamSo that the loads cannot be transffered

easily in the Y-DirectionWe can conclude

that the frame is weak in the Bi-lateral

stiffness in the Y-Direction 

 

 

4.DUCTILITY -

ductility is a property of material which shows 

large undergoes deformation without failure 

-ductile material have much more % elogation 

-this term  used in earthquake engineering 

 

a).Ductility along X-Direction:

- As we can see in the above given plan

the beams are connecting all the columns

in the  X-Direction  and the stiffness is more

in the  X-Direction because number of columns

are more in the  X-Direction

- So the  ductility

in the X-Direction will be reduced .

 

a).Ductility along Y-Direction: 

-As we see in the given plan that the beams

are not connected to each and every 

columnof this frame in the Y-Direction 

-Stiffness of theframe in the Y-Direction

is less because lesser

number of beams in the X-Direction

- So we can conclude the frame is more

   ductile in the  Y-Direction than in X-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.

 

 

the possible sources of irregularity

in the building shown here

-soft storey irrregularity :

-

 

1.-in here we can clearly seen ground 

floor portion is fully open behave 

open storey and 

-column size is also high with 

respect to another storey so 

-when earthquake will comes 

this storey behave  like soft storey 

mecanazim 

-2. above floor are stiff and hard 

and also provide masonary infills 

in above floors 

 

-so building is torsionally sensitive 

-and also shape and size and  

location of diffrent strctural members 

are diffrent 

-in top storey mostly load comes not a 

whole building , but it comes only few

portion of building so it is not eaisily transfer to 

ground 

-so we can say that structure  should be 

build in well symmetrical  manner 

-mass irrregularity providing by used 

of light weight concerete /low weight 

masonary/ or providing much more 

wood material at top levels in building.

 

-columns providing in structure in same size 

and same height in each levels in plan 

-all memebers provided  in symmetrical plan .

-in ground floor open storey mostly not allowed 

-providing sufficient shear walls at a particular 

location 

-because location of shear walls play is important 

roll and shear walls mostly provided in all 4 major 

direction .

 

 

 

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-

in here structure are not symmetric 

-because of diffrent storeys columns 

and beam sizes are  very diffrent 

-and there is no providing proper 

masonary in fills walls or shear walls 

-so diffrent columns and beam sizes 

when earthquake comes all structural 

members as well as architectural elements 

sway and move ,

because of large ecentricity b/w these 

members and redundancy in

vertical direction is not provided

structure will be collapse

and show sudden failure .