Conceptual design of a building with columns and shear walls
1.
| Restraints of floor shrinkage |
Observation Conclusion |
Full restraints at all corners Have high restraints to shrinkage.thus leads to crack |
Corners are left free but restarints along the edge Average |
Non uniform restraints Not effectively restrain shrinkage,so possibly less cracks |
| Lateral stiffness |
Observation Conclusion |
Comparatively lower lateral stiffness in both X and Y - |
Uniform and Comparatively higher lateral stiffness in both X and Y Provide higher lateral stiffness for pure seismic acceleration in X and Y direction |
Non Uniform lateral stiffness in both X and Y |
| Torsion with respect to vertical axis |
Observation Conclusion |
Corner wall provide more resistance to twist Best option with respect to torsional resistance |
Edge walls provide good resistance to twist - |
Irregular walls provide very poor resistance to twist Worst one |
| Vertical reinforcement for similar base capacity |
Observation Conclusion |
Walls are subjected to nominal flexural moment and heavy twisting moment - |
Walls are subjected to nominal flexural moment Require least vertical reinforcement |
Walls are subjected to heavy flexural moment and twisting moment Require higher vertical reinforcement |
| Static eccentricity |
Observation Conclusion |
Structurally symmetric - |
Structurally symmetric - |
Un-symmetric Have static eccentricity and is significant |
| System redudancy |
Observation Conclusion |
Uniform placement of lateral load supports in both axes More redudant |
Uniform placement of lateral load supports in both axes More redudant |
Concentrated lateral load supports in both axes Less redudant |
| Foundation system |
Observation Conclusion |
Due to L shaped walls the geometry of foundation and its design will critical Recommended to have peripheral box foundation |
Walls are in line, easy to fix the geometry and design of foundation Shall be incorporated with isolated/strip footing |
Walls are in line & concentrated easy to fix the geometry of foundation but critical in design Shall be incorporated with isolated/strip footing |
| Architectural constraints |
Observation Conclusion |
Walls obstruct only corners It is preferred one |
Walls obstruct the face of building It is subjected to discussion |
Vertical wall will not allow passage Will not accepted both architecturally and commercially |
2.Issues in the given framing plan:
Indirect lateral load transfer in X and Y direction - The beam are connected to another beams which is ineffective during lateral load transfer .In such condition,the primary beam is prone to shear failure.
Eccentricity - The longer the distance between centre of mass and centre of stiffness, the higher torsional moment of building.As per the given plan eccentricity the building is subjected to higher torsional moment in both x and y directions
Strong beam weak column possiblity - The size of column majorly mentioned as 25 cm x 25 cm.But all the beams have much deeper section.Inertia of beam is visully higher than column.if column reinforcement is adequatly greater than that of beam,we are okay and since we do not have the reinforcement details.
3. Floor plan -It 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 accomodated.
Random internal columns - 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 desing those columns for only gravity loads.
Floor to floor variations in partition walls and beams - It provide important mass control in a building and beams play key role in shear transfer from floor to beam.all these elements are not in order.so heavy distortion and distribution of lateral loads will happen.
Suggestions :
* Heavy torsional forces should be controlled by respective lateral load system.so corner shear walls are suggested
* The proportion of floor area is greater on the left side than the right side so corner shear walls on the left side should be heavier than the right
* Corner shear walls shall preferably be supported over a box foundation.shear walls should be connected by link beams to transfer shear from one to another
* The internal columns shall be supported by isolated footings.The isolated footings can be connected with shear walls through tie beams