Conceptual design of a building with columns and shear walls

Question 1:
The building shown, 20 × 35 m in plan,

has columns on a 5 × 5 m grid

and shear walls (with dimensions shown

in m, 250 mm in thickness) in three

alternative arrangements, (a), (b), (c),

all with the same total cross-sectional

area of the shear walls.

Compare the three alternatives,

taking into account the restraint of floor shrinkage,

the lateral stiffness and the torsional one with respect to the vertical axis,

the vertical reinforcement required for the same total flexural capacity at the base,

the static eccentricity,

the system’s redundancy, foundation systems,

architectural constraints etc.

 

ANS-

 

When structure are having symmetry 

in plan then our structure are more 

stable in any situation .

-so structure is more restrained it 

will be more shrikage , expanding 

and comes cracks are more .

 

-so in plan 1 comes more cracks and 

deflection chances will we high wrt. to 

structure 2and 3 

 

but structure c , having diffrent shapes wall 

so plan c is torsionally weak 

because of in plan c , center of mass of total 

plan wrt. eccentricity of these plan will be 

changed .

-so we can say that if in  structure 

walls having diffrent sizes there 

there eccentricity will be changed 

so earthquake comes near to 

pheriphery of plan and due to

diffrent vibrations comes near the

base portion so plan will be comes

into rotation  condition 

-

-redaundancy plan a and b , more 

with res[pect to  plan c 

because there will be an eccentricity is more 

in plan c in left side 10 m wall ,

which cannot carry structural load 

 

-lateral stiffness plan c , is more 

wrt. plan a and b 

because off eccentricity in plan c 

wall provided 10m  size  left side 

will comes and more  and increase distance

between center of mass plan and eccentricity 

of whole structure so rotation will

comes  .and structure are not able to carry 

equal load either both direction equally 

so much more damaged held in plan .

 

 

 

Question 2:
Discuss the suitability for earthquake resistance of the moment resisting

framing plan of a three-storey building depicted here (cross-sectional dimensions in cm),

the eccentricity of the centre of mass (as centroid of floor plan) to the centre of stiffness

(from the moments of inertia of the columns) are shown. Suggest an alternative. Also,

is there torsional flexibility? Are the two fundamental translational modes of vibration

larger than the fundamental torsional mode of vibration. Discuss qualitatively.

 

ans.

there is 2 way eccentricity in frame

  along x and y direction 

-also with  stiffness eccentricity - 

 x direction larger when compared to

  y direction .

 

-there is 2 continious frame in structure

that B1 AND B2  in the x direction

and B9,B10,B11,B12 In y direction 

-all other beams are broken

in midway in frame .

-

-there will be torsional flexibitlity

in this structure .

-to avoid torsional restrains 

is better to make rooms dimesions 

even in x and y direction .

-to provided columns in  junction

of 2 walls if it is fesiable  better 

-and to provided shear walls

in appropriate location 

-fundamental translation mode of vibration

is larger than fundamental torsional  mode

of vibration 

 

Question 3:

A multi-storey building with basement,

with a quadrilateral (non symmetrical floor plan)

 plan as, has interior columns in an irregular

(not in a grid) pattern in plan that serves

architectural and functional considerations. Partition walls and interior beams supporting the slab have different layout in different stories. However, there is no constraint to the type, location and size of the lateral force resisting components and sub-systems on the perimeter. Proposals are to be made and justified for the choice of the lateral-load-resisting system and its foundation.

ANS .-

In above plan there is totaly

unsymmetry because of columns

are not provided properly

grid pattern .so structure

are unsuitable to design

to any zone , 

-if we reduced weight of this structure

and provided  flat slab in wooden structure

-and also not provided beam

connected to columns because of

we are not eaisily able to make ,

proper beam columns connection

and proper detailig/reinforcement

we are not eaisily provided

according to code 

so provided flat  slab 

is more appropriate than

a regular beam column

connection  .