Concept on positioning of Columns

Week-4 Challenge

1Q.

Answer:

1. Symmetry

Examining the symmetry of the framing plan's elements, it can be seen that the distribution of mass and stiffness is uniform throughout the structure.It is regarded as having one of the best symmetrical features.As a result, both of the two horizontal displacements in each of the two orthogonal horizontal directions tend to be lessened.
It also has excellent uniformity.

2. Redundancy

The plan's Periphery is missing structural components.As a result, the effects of earthquake action are distributed unevenly and nonlinearly throughout the plan.Because there is very little energy dissipation throughout the structure, it is an unreliable structure.

3. Bi-directional stiffness

The building's design might not be able to withstand horizontal seismic actions in the shorter direction (Y-axis), and the stiffness and resistance in that direction are also lower than in the longer direction (X-axis).

4. Ductility

Inelastic Response might result from the building's inability to withstand the elastic earthquake forces in the shorter direction (Y-axis).Ductility will make up for the decreased Design force in the shorter direction (Y-axis).

2Q.

Answer:

• Soft Storey
• Flexible Structres in Torsion

1. Stiffness Irregularity

• When compared to the levels above, the open story at mid-height exhibits significantly less lateral stiffness because the structure ends at this height.
• It is believed that the open storey reduces the building's stiffness and draws more lateral seismic excitation to that floor, severely damaging the upper floors.
• The irregularity can be eliminated by adding shear walls to this high-risk floor for seismic activity.
  
  

2. Mass Irregularity

• Because there is a high mass concentration above the open floor, the open story also contributes to the building's mass irregularity.Therefore, higher floors can support more weight than open floors.
• Additionally, there are more floors above this open floor.

3. Vertical Geometrical Irregularity

• Due to the open storey in the middle of the building and the vertical geometry of the structure, which results in variations in the length of the top storeys along the building unit, there is a change in the horizontal dimension of the lateral force resisting.
• As a result, the building experiences torsional effects that must be decoupled by using shear walls or decoupled moments.
• It is necessary to provide Ductility in order to make up for the Flexibility provided due to variation.

3Q.

Answer:

The collapse of the building was caused by torsional effects as well as orthogonal horizontal ground excitation.Despite having earthquake resistance for the two aforementioned actions,

The following are the responsible factor;

1. Show the Ground Floor

2. The perimeter's two short sides are filled in.

3. Exceptional left-hand bay Staircase with Concrete-filled Interior

4.Columns that don't follow a line

1. Ground Floor:

• The building's ground floor is open, and it may be a soft storey with long columns. As a result of the ground floor's excitation, the columns may not have been able to withstand the earthquake and may have collapsed.
• This mechanism is referred to as a soft storey.
• Having a strong column-weak beam mechanism can prevent this.

2. Perimeter of two short sides of the building:

• Due to the fact that the two sides of the building's perimeter are filled in (possibly with soil), which results in an irregular distribution of mass known as mass irregularity, the mass has been unevenly distributed in all of the building's sides and throughout all of its storeys.
• This can be prevented by building shear walls along the perimeter's two short sides, which can withstand lateral loads (soil from infill) and stiffen the building's frame to withstand earthquake actions.
• Additionally, it modifies the plan's Mass Irregularity.
  
  

3. Staircase:

• Concrete staircases are located in the extreme left-hand bay, which caused the mass to become concentrated there. As a result, torsional effects were created with the base of the mass concentration in the staircase.
• The stairs should be kept in the center of the building, which makes the torsional effect zero by uncoupling the moment, to prevent this kind of failure.Additionally, it has implications for the building's irregular floor plan.

4. Column:

• It has been noted that the columns in the extreme left-hand middle line have a deviation in the construction's line at the staircase, which is another factor contributing to the plan's irregularity and torsional flexibility.
• To prevent this, it is important to keep the eccentricity within the bounds of the beam and column sizes.
• The sizes of the beams and columns in the plan should also be changed so that the columns' lines remain straight throughout the staircase area.
  
  

----------------------------Thank You-------------------------------------