What is a Shear Wall?  Types of Shear Wall Designs| Importance of Shear Wall

What is a Shear Wall?  Types of Shear Wall Designs| Importance of Shear Wall

What is a Shear Wall?

A shear wall is a vertical part of a structural system that is designed to resist in-plane lateral forces, generally wind and seismic loads. These walls are typically used in high-rise multi-stored buildings, which are usually subjected to seismic and lateral forces.

Shear walls are walls made of concrete blocks that are spaced at a height to allow for beams placed on top of the blocks to span the entire wall.

The shear wall has “flanges” which provide additional stability and protection against weathering or crushing damage. A shear wall is also known as a braced frame structure in some areas.

Shear walls are a perfect example of how a home’s design is affected by the geographic location in which it is built.

In areas where extreme weather is a factor, such as heavy winds and hurricanes, shear walls are an important consideration.

In these areas, the shear wall acts as a diaphragm that helps stabilize the building from vertical movement caused by wind.

In areas that do not experience hurricane-force winds, the shear wall serves to create stability for other structural problems such as earthquakes.

Applications of Shear Wall Designs

Shear walls provide lateral resistance to wind and seismic loads. In the event of a building failure, shear walls provide additional stability. \

They are used for strengthening a structure or anchoring utility services such as telephone lines, water pipes and electrical lines.

Shear walls retain the wall from moving towards the foundation due to ‘gravity’ forces exerted on it.

Shear walls in a structure separate the boundary walls from the roof structure.

Shear wall in a seismic building provides lateral resistance to wind and seismic loads. In the event of a building failure, it provides additional stability.

Shear walls are used for any building project, either as a standalone building element, or as part of an engineered frame system. They are used to provide lateral resistance to wind and seismic loads.

Shear walls are used as a component part of an engineered system, which results in the resistance being transferred into the surrounding columns.

Shear walls are used as a component part of an engineered system, which results in the resistance being transferred into the surrounding columns. T

hey can be fitted without interior bracing for special situations (for example, concert halls). Lateral loads transmitted through shear walls allow vertical loads to be transferred to other members without additional bracing.

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Structurally speaking, although the best location for providing shear walls is in the center of the building. But since it is not practical, the choice of location of the shear wall is usually decided after a complete structural analysis.

● The Structural Plan.

● The Location.

● The Symmetry of the Building

● And finally, the Lateral force that gets exerted on the structure. 

The Thickness of Shear Wall

The general thickness of shear walls ranges from 150mm to 400 mm. The minimum nominal thickness of shear walls for one-story RCC buildings is 150 mm, and masonry shear walls are 203 mm.

Types of Shear Wall

Reinforced Concrete Shear Wall

 These are the most common type of shear walls. The walls consist of reinforcements and concrete slab and vary within a 140 mm to 400 mm thickness. The shear wall’s rebars run from the foundation and up to the top edge of the building. 

Concrete Block Shear Wall

 Unlike regular RC Shear walls, these walls are made up of hollow concrete blocks with reinforcement bars being arranged through the concrete blocks’ hollow area in both the vertical and horizontal directions. Due to this, they can take both vertical and horizontal loads. 

Steel Plate Shear Wall

 Columns and boundary columns are bound steel plate walls with horizontal beams. The steel plate walls operate as the web of the vertical plate girder and the columns as flanges, Thereby making this wall to be able to withstand high seismic force. 

Plywood Shear Wall

  These are walls made out of plywood along with chords and base connections. The plywood distributes the sheer force while the chords resist tension and the base connections distribute that load to the foundation. 

Reinforced Hollow Concrete Wall Masonry (RCHCBM)

 Reinforced Hollow concrete wall masonry consists of reinforcement in both the vertical and horizontal directions of the masonry blocks. These walls are designed to counter lateral seismic load and wind force, providing three-dimensional stability to the structure. 

Shear Wall Design

Here’s a step by step procedure for designing of Shear Wall. Please note that the process involves following the Design Standard codes or International Building Code per respective the country for design considerations. 

1. Locating and reviewing the layout of the cantilever walls.
2. Serving the gravity loads and equivalent masses.
3. Determining the earthquake design force.
4. Selecting the structural design and analyzing it.
5. Design for Flexural Strength.
6. Design for Shear Strength
7. Design of Reinforcement. 

Shear Wall Reinforcement In Detail

Advantages And Disadvantages of Shear Walls.

There are advantages and disadvantages to the use of shear walls.

Advantages of Shear Walls.

1. Lateral resistance to wind and seismic loads
2. Transferred loads from shear walls to other supporting elements/columns
3. Shear walls allow vertical loads to be transferred to other members without additional bracing.

Advantages of Shear Walls.

1. Lateral resistance capacity in composite structures is limited due to shallow wall thickness in composite structures
2. High material costs for concrete and steel shear walls
3. Shear walls may only be used as part of an engineered frame system
4. Possible difficulty in maintaining and replacing shear panels
5. Shear walls cannot provide lateral resistance to all types of loading and seismic design requirements.

Shear Wall FAQs

What exactly is a shear wall?

Shear wall is a strong vertical diaphragm capable of transmitting lateral pressures from external walls, floors, and roofs to the ground foundation in a direction parallel to their planes in building construction. Reinforced concrete walls and vertical trusses are two examples.

Why are shear walls provided?

Shear walls offer substantial strength and stiffness to structures in the direction of their orientation, reducing lateral sway and, as a result, damage to the structure and its contents.

Because shear walls carry high horizontal earthquake stresses, their overturning consequences are significant.

How thick should shear wall be?

Masonry shear walls must have a minimum nominal thickness of 8 inches (203 mm). Shear walls in one-story structures are allowed to have a minimum nominal thickness of 6 inches (152 mm).

Shear walls in the foundation have a major contribution to the overall strength and stiffness of a structure.

How is shear wall designed and works?

Shear walls are designed so that they carry most of their load in tension, applying only a small amount of compressive force to connections with other structures.

A shear wall is stiffer along its primary axis than along its secondary axis. It is regarded as a fundamental structure because it offers rather stiff resistance to vertical and horizontal forces operating in its plane.

A shear wall produces compatible axial, shear, torsional, and flexural stresses under this combined loading situation, resulting in a complex internal stress distribution.

Loads are transmitted vertically to the building’s foundation in this manner. Geometry, loading, material characteristics, constraint, and structure are all variables that influence the failure process.

What are the types of shear walls?

There are different types of shear walls in most structures. Some examples are:

– Plywood shear walls:

Plywood shear walls are a form of conventional wall that is also known as timber shear walls. It is made out of plywood sheets and studs.

Shear force is transferred by plywood sheets, whereas tension or compression is resisted by studs.

Nowadays, plywood shear walls are being modified to take advantage of new technological advances. Steel sheets, sure boards, and other materials are being used in place of plywood.

-Concrete shear walls:

Concrete shear walls are formed when steel or reinforced concrete binding frames and webs are constructed using reinforced concrete.

Concrete is poured in place, and steel or reinforced concrete studs, ties, and rebars are added. These steel and concrete members resist the wind and seismic forces.

-Wood shear walls:

Wood shear walls are made out of structural beams, planks, joists, and other lumber materials. Unlike concrete walls, wood is less expensive to make.

Wood studs are nailed to the beams or beams are nailed to the studs. Wood shear walls begin with the studs that are nailed to the supporting beams or beam connected to the wall.

The studs are usually 2 x 4, 2 x 6, or 2 x 8. The framing can include plywood, OSB, or sheathing made of another material.

Wood shear walls are used in areas where earthquakes are not a concern. These walls offer less resistance to wind and seismic forces than concrete or steel shear walls.

– Steel Shear Wall:

Steel shear walls are constructed of steel beams or steel rods. A steel shear wall is made up of three parts: a steel plate wall, a boundary column, and a horizontal floor beam.

The motion of a steel shear wall is similar to that of a plate girder. Steel plate walls serve as plate girder webs, boundary columns serve as flanges, and horizontal beams serve as plate girder stiffeners.

What are the benefits of the shear wall?

Shear walls have many advantages over other structural systems in buildings during an earthquake event.

One of the advantages is that shear walls can be designed to transfer center-of-gravity load from one building component to another, which results in a greater level of structural stability, and can help to minimize damage during a seismic event.

Shear forces help transfer the overall weight of a structure from one connection to another. Skilled engineer can calculate shear wall loads for a building and properly design it.

Shear walls are very effective in reducing or eliminating deflection caused by earthquake forces.

What are the main advantages of using a shear wall?

For structures subject to earthquake loads such as those in California, such walls add structural stiffness and resistance by way of lateral bracing.

They also add to the overall strength and stability of the structure due to additional support that they provide to roofs and other structures.

How do you identify shear walls?

In drawings, shear walls are often denoted by a solid line with a narrower line indicating the sheathing that will cover it (and which is usually then specified in a separate sheathing schedule).

Shear walls are only one of the numerous construction components depicted on architectural drawings.

What are the forces acting on the shear wall?

A shear wall is a building element, such as a bridging truss, that resists lateral loads such as wind and seismic forces by transferring these lateral forces to supporting elements such as walls or columns, or other structural elements such as beams or slabs.

Some forces that act on it include;

1. Lateral force of earthquake:

The major lateral force from an earthquake or high-wind event causes uplift, compression, and sliding forces to occur at the same time.

2. Gravity loads:

Gravity loads to the vertical and horizontal forces occurring at the same time.

2. Uplift force:

Applies to the vertical load. Lateral forces attempt to roll the wall away from the foundation, causing uplift at one end of the wall assembly.

3. Compression force:

Applies to the vertical ones that are at the top of the wall or frame. These are usually caused by wind load or volume reduction strategies, which is considered as a “side” effect, which acts upon the building’s structure, although it does provide an overall stiffness for load distribution.

While one end of the wall is being lifted, the opposing end is being compressed. As the structure shakes back and forth, these loads alternate

4. Shear loads:

The resistance to horizontal shear, torque or axial forces occurring at any point along the member at any point in rotation.

5. Slide forces:

Applies to the horizontal loads. The few anchor bolts present attempt to oppose the lateral force that attempts to slide the wall off the base, however the bolts are unsuccessful.

What type of material is used for shear walls?

Shear walls can be made out of wood, steel, concrete and masonry materials. Wood and steel shear walls are more common than concrete or masonry shear walls because they are less expensive than other materials.

Why is shear wall important?

Shear walls provide large stiffness and strength to buildings, which effectively reduces lateral deformation of the structure and hence reduces damage to the structure.

Shear wall is used in seismic design of framed steel or composite steel and concrete buildings generally tall buildings.

What is shear wall failure?

Shear wall failure is the failure of a shear wall to resist loads applied in the plane of the wall. The failure mechanism may involve buckling, shear fracture, or both.

If the structural walls are not appropriately strengthened, they may break due to brittle flexural failure under lateral stress.

This failure process is caused by the global tension/compression combination, which creates pure axial tension in the outermost shear walls.

Do shear walls need columns?

Shear walls transfer lateral loads into vertical load paths that are anchored to the foundation. Shear walls are not self-supporting elements. Shear walls need to be supported by columns that transfer the load to the foundation.

Shear wall failure is caused due to horizontal forces acting on them while they are not transferred into vertical loads acting against gravity and base isolation.

Shear walls should be constructed along the length and breadth, ideally both. However, if they are only given in one direction, a suitable grid of beams and columns in the vertical plane (known as a moment-resistant frame) must be provided in the opposite direction to withstand significant earthquake impacts.