Conceptual design of a building with columns and shear walls

Aim:-

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.

Procedure:-

STRUCTURE (A)

1. This structure is considered as it is asymmetric in nature.
2. Here cannot be considered as horizontal irregularities and the shear wall shape is like L.
3. There is some uncertainty concerning certain features of the seismic response of non-rectangular walls.
4. It occurs lack of tensile capacity and force configuration.
5. These walls have high stiffness and strength in both directions, hence are subjected to biaxial bending and bi-directional shears during earthquakes.

STRUCTURE (B)

1. For this structure frame can be considered as symmetric in placed the shear walls.
2. The walls of a wall system of this frame could be arranged in two horizontal directions with as much two-way symmetric as possible.
3. The shear walls are arranged similarly and symmetric, so it can be considered at every story to be fairly uniformly resistant to seismic forces and deformation demands, minimizing the uncertainty about the seismic response.

STRUCTURE (C)

1. This structure can be considered asymmetric in nature because the shear wall are provided are not arranged in two orthogonal horizontal directions.
2. The center of mass and center of gravity of such structure will not lie far away from each other enabling transitional modes in the first two principles modes.
3. The foundation, shear wall and columns are arranged in different arrangements, so here take up huge amount moments in case of during earthquakes,
4. This type of shear wall system will not carry the load equally in either directions. So this structure has lack of redundancy.
5. On the left-hand side, the wall provides more eccentricity, and lateral stiffness is more. Therefore it occurs then the damage or failure will be less.

Aim:-

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.

1. 

Answer:-

1. 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.
2. There is only two continuous frames in the structure that is B1 and B2 in the X direction and B9, B10 and B11, and B12 in the Y direction, and all other beams are broken at midway in the frame.
3. There will be Torsional flexibility in the structure.To avoid torsional restraints it is better to make the room dimensions even in both X and Y direction and placing the columns at the junction of two walls if it is feasible better to provide a shear wall at the appropriate location.
4. The fundamental translation mode of vibration is larger than the fundamental torsional mode of vibration.

Aim:-

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.

Answer:-

1. The above plan that is given is totally unsuitable for normal areas and also in Earthquake prone areas.
2. In the seismic region, the lateral and vertical loads play important criteria because it helps in resisting the failure of the earthquake as the loads. The resultant will not co-inside with the center of the mass of the structure it becomes eccentric and not suitable for any type of area.
3. In this plan, a flat slab is more appropriate than a regular beam-column junction as it provides support to the columns without any provision of the beam which reduces the weight of the building and also helps in ductility which indirectly helps to maintain the structure in the earthquake-prone areas.
4. Apart from a flab slab, a wooden structure is also appropriate which reduces the weight of the building and also helps to maintain the structure in the earthquake-prone areas