Conceptual design of a building with columns and shear walls

Q.1

ANS:

Naming the figure fig A, fig B and fig C getting the conclusion with the help of table

fig A fig B fig C

1. Restraint floor shrinkage:
2. Observation:
3. Fig A: full restraints at all corners
4. Fig B: corners are left free but restraints along the edge

• Fig C: non-uniform restraints

1. Conclusion:

Fig a will have higher restraint to shrinkage, thus lead to cracks in the floor. Fig b is average and fig c will not effectively restrain the shrinkage, so possibly less cracks

2. The lateral stiffness:
3. Observation:
4. Fig A: comparatively lower lateral stiffness in both X and Y
5. Fig B: Uniform and comparatively higher lateral stiffness in both x and y
6. Fig C: non uniform lateral stiffness in both x and y
7. Conclusion:

Fig b will provide higher lateral stiffness for pure seismic acceleration in x and y direction

3. Torsion with respect to vertical axis:
4. Observation:

• Fig A: corner walls provide more resistance to twist
• Fig B: edge walls provide good resistance to twist

1. Fig C: irregular walls provide very poor resistance to twist
2. Conclusion:

Fig a will be best option with respect to torsional resistance where option c is the worst one

4. Vertical reinforcement for similar base capacity :
5. Observation:
6. Fig A: wall are subjected to nominal flexural moment and heavy twisting moment
7. Fig B: wall are subjected to nominal twisting moment

• Fig C: walls are subjected to heavy flexural moment and twisting moment

1. Conclusion:

Fig c will require higher vertical reinforcement and fig b will required the least

5. Static eccentricity:
6. Observation:

• Fig A: structurally symmetric
• Fig B: structurally symmetric

1. Fig C: un-symmetric
2. Conclusion:

Fig c will have static eccentricity and it is significant

6. Systems redundancy:
7. Observation:

• Fig A: uniform placement of lateral load supports in both the axes
• Fig B: uniform placement of lateral load supports in both the axes
• Fig C: concentrated lateral load supports in both the axes

1. Conclusion:

Fig a and b are more redundant the fig c

7. Foundation system:

• Observation:
• Fig A: due to ‘L’ shaped walls the geometry of foundation and its design will be critical

1. Fig B: walls are in line. Easy to fix the geometry and design of foundation

• Fig C: walls are in line & concentrated. Easy to fix the geometry of foundation but critical in design

1. Conclusion:

Fig b and fig c shall be incorporated with isolated footings/ strip footing fig a is recommended to have peripheral box foundation

8. Architectural constraints:
9. Observation:

• Fig A: walls obstruct only corners
• Fig B: walls obstruct the faces of building
• Fig C: vertically wall will not allow pass

1. Conclusion:

Fig b and fig c shall be incorporated with isolated footings/ strip footing fig a is recommended to have peripheral box foundation

Q.2

ANS:

1. Indirect lateral load transfer in x and y direction – the beam are connecting to another beams which is ineffective during lateral load transfer. In such conditions, the primary beam is prone to shear failure
2. Strong beam weak column possibility- the size of column majorly mentioned as 25cm x 25cm. but all the beam have much deeper section (50cm). inertia of beam is visually higher than that column. If the column reinforcement is adequately greater than that of beams, we are okay and since we do not have the reinforcement detail, this is doubtful it is recommended to have slight bigger size for column
3. Eccentricity- the longer the distance between center of mass and centre of stiffness the higher torsional moment of the building as per the given plan eccentricity the building is subjected to higher torsional moment (torsional flexibility) in both x and y direction
4. Alternate scheme:

Q.3

ANS:

1. Floor plan – the floor plan of building is not either uniform or symmetric. So naturally any lateral load induced in the floor will not have 100% influence in same direction. Definitely a special lateral load resisting system for these torsional moment should be accommodated
2. Random internal column- since the internal columns are random they are unable to transfer lateral loads efficiently and can not achieve desirable building response. So we have to assume and design those column for only gravity loads.
3. Floor to floor variation in partition walls and beams- partition walls provide an important mass control in a building and beam play key role in shear transfer from floor to beam. All these element are not in order so heavy distribution of lateral load will happen
4. Suggestion on the lateral load system & its foundation:
5. Heavy torsional forces should be controlled by respective lateral load system. So “corner shear walls” are suggested
6. The proportion of floor area is greater on the left side than the right side (irregular quadrilateral) so corner shear walls on the left side should be heavier than the right
7. Corner shear walls shall preferably be supported over a box foundation. Shear walls should be connected by link beam to transfer shear from one to the other
8. The internal column shall be supported by isolated footing. Those isolated footing can be connected with shear walls through tie beam
9. Proposed schematic plan of lateral load system:

Suber structure

sub-structure