Conceptual design of a building with columns and shear walls

Q1

Answer

• RESTRAIN OF FLOOR SHRINKAGE

Observations

• Fig1 - full restrain at all corners
• Fig2 - corners are left free but restrained at the edges
• Fig3- non uniform restrain.

Conclusion

Option a will have higher restrain to shrinkage and hence there will be a crack, option b is average,

Option c have effectively less shrinkage and hence there will be less crack.

• The lateral stiffness

Observations

• Fig1 - comparitively lower stiffness in x and y directions
• Fig2 -uniform and higher stiffness in x and y directions
• Fig3- non uniform lateral stiffness in x and y directions

Conclusion

option b will provide higher lateral stiffness for a pure seismic acceleration in x and y directions

• Tension wrt to verticle axis

Observations

• Fig1 - corner wall provide more resistance to twists
• Fig2 -edge wall provide good resistance to twists
• Fig3- irregular wall provide very poor resistance to twists

Conclusion

option a will be the best and option c is worst wrt torrsional resistance

• verticle r/f for similar base capacity

Observations

• Fig1 -walls are subj to nominal flexural moment and heavy twisting moment
• Fig2 -walls are subj to nominal twisting moment
• Fig3- walls are subj to heavy flexural moment and twisting moment

Conclusion

option c will req higher verticle r/f and option b will require the least

• static eccentricity

Observations

• Fig1 -structurally symmetric
• Fig2 -structurally symmetric
• Fig3- structurally un symmetric

Conclusion

option c will req higher static eccentricity and its significant

• System redundancy

Observations

• Fig1 -Uniform placement of lateral Load support in both axes.
• Fig2 -Uniform placement of lateral Load support in both axes.
• Fig3- Conc lateral support in both axes.

Conclusion

Option a and b are more redundant than option c

• Foundation system

Observations

• Fig1 -due to L shaped wall the geometry of foundation will be critical.
• Fig2 - Wall in line easy geometry and foundation is easy.
• Fig3- Wall in line easy geometry and foundation is easy, but design will be critical.

Conclusion

Option b and c can be incorporated using isolated/strip footing meanwhile option a need box footing.

• Architectural constraints

Observations

• Fig1 -Wall obstruct only at the corner.
• Fig2 - wall obstruct at the face.
• Fig3- vertical walls will not allow passage.

Conclusion

Architectural viewpoint option a is accepted, meanwhile option b can be discussed but option c will not be accepted architectural or design pov.

Q2

Answer

issues in the given framing plan

indirect lateral load transfer in x and y direction - the beam connected to other beam is ineffective during lateral load transfer and these will result in shear failure in primary beam.

eccentricity - the longer the distance between the center of the mass and the center of the stiffness the higher will be the torrsional moment of the building. as per given plan the eccentricity the building is subjected to higher torssional moment in x and y direction

strong beam weak column possibility - the size of colmn is 25x25cm but the beam us having much deeper section 50cm. inertia of beam is higher than on the column if r/f of column is higher than the beam we are okay but we dont have r/f details this is doubtful hence we should have higher column sizes

different approach to framing plan will solve this issue

Q3

Answer

observation in framing plan

floor plan - the floor plan of building is neither uniform nor symmetry so naturally the lateral force induced in the floor will not have 100% influennce in same direction. special load resisting system for these torsional moment should be accomodated

random internal columns- since the internal column are random the are unable to transfer load efficiently and cannot acheive desireable response so we have to assume the design is only for gravity load.

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 is not in order so heavy distortion and distribution of lateral load will happen.

suggestion on the lateral load sys and its foundation

• 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 (Irregular quadrilateral). 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 the other.

• The internal columns shall be supported by isolated footings. Those isolated footings can be connected with Shear walls through Tie beams.

proposed plan for lateral load sys