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 .