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Location of shear walls in High-rise RC buildings

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How to identify the optimum location of shear wall in high rise building?

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This is a very good question.

An optimal location of shear walls in a high rise building depends on its architectural features that dictate the mass distribution of the structure as well as the lateral force resisting system of the structure. As a structural engineer, you will have to try different locations considering that optimal location will be one that shall result in centre of rigidity of structure being closet to centre of mass. This is the general principle.

Edited by Ayesha

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yepp agreed with @Ayesha its depends on your layout and architectural work, but the best way to do it is place the shear wall on the place closest to centre of mass this already proved by some journals on internet as a kind of optimum place to put the shear wall on, but the internal forces of shear wall would have a bigger result cause it tends to withstand more mass you should try several numbers of model to pick which one the best in reducing structural displacement and withstand internal forces.

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4 hours ago, Ayesha said:

This is a very good question.

An optimal location of shear walls in a high rise building depends on its architectural features that dictate the mass distribution of the structure as well as the lateral force resisting system of the structure. As a structural engineer, you will have to try different locations considering that optimal location will be one that shall result in centre of rigidity of structure being closet to centre of mass. This is the general principle.

To further elaborate on the my above reply paragraph, the extent to which a wall will contribute to the resistance of overturning moments, story shear forces, and story torsion depends on its geometric configuration, orientation, and location within the building. While it is relatively easy to accommodate any kind of wall arrangements to resist wind forces, it is much more difficult to ensure satisfactory overall building response to large earthquakes when wall locations deviate considerably. This is because, in the case of wind, a fully elastic response is expected, while during large earthquake demands, inelastic deformations will arise.

 The major structural considerations for individual structural walls will be aspects of symmetry in stiffness torsional stability, and available overturning capacity of the foundations. The key in the strategy of planning for structural walls is the desire that the inelastic deformations be distributed reasonably uniformly over the whole plan of the building rather than being allowed to concentrate in only a few walls. The latter case leads to the underutilization of some walls, while others might be subjected to excessive ductility demands. 

As far as the general practice goes, elevator shafts and stairwells lend themselves to the formation of reinforced concrete core. Traditionally, these have been used to provide the major component of lateral force resistance in multistory office and residential buildings. A centrally positioned large core may also provide sufficient torsional resistance without requiring additional perimeter framing.

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I would just add that in choosing suitable locations for structural walls, the following additional aspects should be considered:

1. Locate the walls at the perimeter or periphery of the building to get the best torsional resistance.

2. Locate your walls so that they carry as much gravity load to the foundations as possible. This would reduce uplift forces in the foundation and also would reduce flexural reinforcement demand in the wall.

Thanks.

 

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2 hours ago, UmarMakhzumi said:

2. Locate your walls so that they carry as much gravity load to the foundations as possible. This would reduce uplift forces in the foundation and also would reduce flexural reinforcement demand in the wall.

 

But keep in mind, this would change the building system and R factor.

 

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1- Place shear walls opposite to each other, let's say you put a wall at the far right of a building, put another one with the same length and thickness at the far left one, .. etc that is to ensure the center of rigidity ( governed by walls mostly) coincides with the center of mass of the building to eliminate torsional movement of the building.

2- The far the wall is placed from the center of the building the better, as walls near the center doesn't resist much shear force as walls at the outer perimeter and the latter is good to prevent torsional movement.

3- The following is copied directly from the ACI design hand book:

''

Shear walls should be located within a building plan to efficiently resist lateral loading. Locating shear walls in the center half of each building is generally a good location for resisting lateral forces. This arrangement, however, can restrict architectural use of space.

Although shear walls are commonly located at the ends of a building, such wall locations will increase slab restraint and shrinkage stresses, especially in long buildings and buildings such as parking structures that are exposed to large temperature changes. Symmetrical wall arrangements provide good flexural and torsional stiffness. Walls at the perimeter resist torsional forces most effectively. Walls away from the perimeter, however, could have a higher tributary area and, consequently, larger gravity axial force to resist uplift or overturning. They are, however, less efficient in resisting horizontal torsion

An unsymmetrical arrangement, however, does not usually provide predictable torsional stiffness due to their eccentricity. Such a shear wall layout should be designed explicitly for torsion. A symmetrical arrangement is preferable to avoid designing walls for torsion.''

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22 hours ago, Omar Khalid said:

1- Place shear walls opposite to each other, let's say you put a wall at the far right of a building, put another one with the same length and thickness at the far left one, .. etc that is to ensure the center of rigidity ( governed by walls mostly) coincides with the center of mass of the building to eliminate torsional movement of the building.

2- The far the wall is placed from the center of the building the better, as walls near the center doesn't resist much shear force as walls at the outer perimeter and the latter is good to prevent torsional movement.

3- The following is copied directly from the ACI design hand book:

''

Shear walls should be located within a building plan to efficiently resist lateral loading. Locating shear walls in the center half of each building is generally a good location for resisting lateral forces. This arrangement, however, can restrict architectural use of space.

Although shear walls are commonly located at the ends of a building, such wall locations will increase slab restraint and shrinkage stresses, especially in long buildings and buildings such as parking structures that are exposed to large temperature changes. Symmetrical wall arrangements provide good flexural and torsional stiffness. Walls at the perimeter resist torsional forces most effectively. Walls away from the perimeter, however, could have a higher tributary area and, consequently, larger gravity axial force to resist uplift or overturning. They are, however, less efficient in resisting horizontal torsion

An unsymmetrical arrangement, however, does not usually provide predictable torsional stiffness due to their eccentricity. Such a shear wall layout should be designed explicitly for torsion. A symmetrical arrangement is preferable to avoid designing walls for torsion.''

Good point again. In such cases, you have to deal with the notorious huge nerve sapping temperature forces.

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