Conceptual design of a building with columns and shear walls

Question 1:
The building shown, 20 × 35 m in plan, has columns on a 5 × 5 m grid and shear walls (with dimensions shown in m, 250 mm in thickness) in three alternative arrangements, (a), (b), (c), all with the same total cross-sectional area of the shear walls. Compare the three alternatives, taking into account the restraint of floor shrinkage, the lateral stiffness and the torsional one with respect to the vertical axis, the vertical reinforcement required for the same total flexural capacity at the base, the static eccentricity, the system’s redundancy, foundation systems, architectural constraints etc.

Restraint of floor shrinkage:

• Option A has full restraint at all the corners
• Option B has left free at the corners but restraint along the edges.
• Option C has Non - uniform restraint.
• From this we can conclude that option (A) has Full restraint so it leads to the cracks in the floor
• Option (B) has at along edges restraint so average shrinkage.
• Option (C) has not effective with restraint so that less cracks .

The lateral stiffness :

• Option A has lower comparatively lateral stiffness
• Option B it is uniform and comparatively higher stiffness
• Option C Non uniform lateral stiffness
• From this option B has Higher lateral stiffness for the sesmic loads

Torsion with respect to vertical axis:

• Option A has more resistance to twist at edges
• Option B has better gain resistance to twist at edge walls
• Option C ha poor resistance to twist at irregular walls
• Option A has have the high torsion with respect to vertical axis.

Vertical reinforcement for similar base capacity:

• Nominal flexural moment and heavy twisting moment at wall in option A
• Nominal twisting moment at wall in option B
• Heavy flexural moment and twisting moment at walls
• From this option C ha higher vertical reinforcement for similar. And option B is less .

Question 2:
Discuss the suitability for earthquake resistance of the moment resisting framing plan of a three-storey building depicted here (cross-sectional dimensions in cm), the eccentricity of the centre of mass (as centroid of floor plan) to the centre of stiffness (from the moments of inertia of the columns) are shown. Suggest an alternative. Also, is there torsional flexibility? Are the two fundamental translational modes of vibration larger than the fundamental torsional mode of vibration. Discuss qualitatively.

• In structure There is a two way eccentricity in the frame along X direction and Y direction also with stiffness the eccentricity in X direction is larger when compared to Y direction.
• There is only two continuous frames in the structure that is B1 and B2 in the X direction and B9, B10 and B11,B12 in the Y direction and all other beams are broken at the midway in the frame
• Eccentricity for the longer distance between center of mass and centre of stiffness.
• Eccentricity of building is higher torsional moment.
• Inertia of beam is visually higher than column .

Question 3:

A multi-storey building with basement, with a quadrilateral (non symmetrical floor plan) plan as, has interior columns in an irregular (not in a grid) pattern in plan that serves architectural and functional considerations. Partition walls and interior beams supporting the slab have different layout in different stories. However, there is no constraint to the type, location and size of the lateral force resisting components and sub-systems on the perimeter. Proposals are to be made and justified for the choice of the lateral-load-resisting system and its foundation.

• The building is not either uniform or symmetric s olateral load induced in the floor will not have 100% ,the lateral load resisting system for thes torional moment should be accommodated .
• the random internal column is unable to transfer lateral load effectively to assume design those column for only gravity load
• Floor to floor variations in partition walls and beams partition wall provide an importance mass control in a building plan 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
• Suggestion on the lateral load system and its foundationheavy tortional forces should be contrrolled by respective lateral load system so corner
• shear walls are suggested the propotion of floor area is greater on ther left side than the right side so corners shear walls on left side should be havier than the right
• corner shear wall shall preferably be supported over a box foundation shear walls should be connected by link beam to transfer shear from one to the other
• The internal columns shall be supported by isolated footing those isolated footing can be connected with shear walls through tie beam