Conceptual design of a building with columns and shear walls

Aim

Conceptual design of a building with columns and shear walls by analyzing the given images.

Ans 1

• Restraint of floor shrinkage

a). As shear walls are placed in corners hold the floor from corner so, it restrain from floor shrinkage.

b). As the shear walls are placed at the floor outer boundary has the better stability near the wall side but cannot restrain at corners.

c). Shear wall are placed it is not in proper format so high shrinkage can occur.

• Lateral stiffness

a). During the seismic force as the shear wall is placed in corner there will be more open mass in the centre so forces are act in the corner and appears to be low lateral stiffness.

b). As the shear walls are placed in both direction and was along the periphery so it will restrain the seismic forces in better way so so it will provide better stability.

c). As the two shear walls are pleased in the same direction the stiffness is increase in that direction and there is only one shear wall in another direction so there is instability of stiffness.

• Torsional stiffness with respect to the vertical axis

a). It's seems from the image that the centre of mass and centre of stiffness is in the same place so there will be no torsional rotation in any direction so it is torsional Stiffen model.

b). As mentioned above the centre of mass and centre of stiffness of the module is in the same place so there will be less chances of torsional rotation.

c). As there is more stiffness towards the left side as shown in the figure so the centre of stiffness shift towards the left side there will be instability of torsion.

• Vertical reinforcement required for the same total flexural capacity at the base

a). As the shear walls are placed in the corner there will be less lateral force appearing towards the shear wall so the requirement of the vertical reinforcement will be considerable lesser.

b). These share walls are are oriented in the direction of the axis so it will go through the sustainable lateral forces therefore vertical reinforcement requirement will be more.

c). As mentioned above this shear walls are placed asymmetrically and the shear wall on the left side will sustain high seismic forces so it require considerable more vertical reinforcement.

• Static eccentricity

a). As shown in the figure and mentioned above the shear wall are placed symmetrically within the layout show centre of mass and centre of stiffness is at the same place so there will be no static eccentricity.

b). Same as above the shear walls are placed symmetrically within the periphery so there will be no static eccentricity occur.

c). It can be seen from the figure that because of the left side shear wall the centre of stiffness is towards the left so the static eccentricity will be their.

• System’s redundancy

a). Because of the the shear wall please in the corners it will not take part in registering the lateral forces actively so their will be less redundancy in structure.

b). As the shear walls are placed symmetrically there will be good redundancy of the structure towards the forces.

c). As the shear walls are placed asymmetrically and the left side share wall have more load so this is low redundant in structure.

• Foundation systems

a). This has the shear wall at the corners the isolated footing is most suitable and connecting with the beams at foundation level.

b). The isolated footing can be used.

c). The separate isolated footing for the left side and combined footing for the right side shear wall is suitable.

• Architectural constraints

a). It is suitable from the architectural point of view because there will be no obstruction for the door window in opening in the wall.

b). In this it may be the obstruction for door and window.

c). In this layout left side of the shear wall will take half of the path so it will not look aesthetically good.

Ans 2

It is seen from the layout that the building is not symmetric to centre of mass, centre of stiffness and eccentric in both x and y direction.

It can be assumed from the layout that the columns is weaker than the beams so the stability towards lateral force is decrease and it is weak column strong beam design criteria.

By adding the shear walls to the structure it can be more sustainable towards the lateral forces.

As it is mentioned that the centre of mass and centre of stiffness is not in the same place and have some eccentricity so the torsional rotation will be there in both the axis.

Translational mode of vibration occur when the transfer of load will be there from beam to column and when the column are not aligned.

Alternative suggestion

The structure should be redesigned like:

the column size should be increased.

the shear wall should be placed.

additional column at some places.

Ans 3.

This quadrilateral plan is is irregular in shape having the partition wall support the floors.

It can be seen from the figure that there should be the difference in centre of mass and centre of stiffness so the structure is not symmetrical, centre of mass is towards the left side .

This will lead to the torsional rotation of the structure when there will be systemic forces.

To overcome this, the shear wall should be provided and the arrangement of the columns should be done properly.

The mat footing or combined footing should also be provided.

Result

Analysis the different conditions of the structural configuration and some basic ideas about orientation and placement of the structural members.

Some important arrangment of the shear walls and reason behind it.

Suggest some alternative for the given plan.