Shear walls significantly reduce the sway of a structure to reduce damage to the structure and its contents. Shear walls do not support lateral loads in the same way that load-bearing walls or columns support vertical loads. The exposed face of the structure transfers wind forces to the adjacent shear walls which then transfer the forces to the foundation and concrete footings through its sheathing diaphragm and hold-down connections.
Composed of framing members, sheathing, nails, and hold-downs, a shear wall creates a complete load path that resists racking. Think of a wooden square with four edges, it has two columns and two beams. This frame can support the weight from above, called compression.
Any load put on the upper beam is transferred through the columns to the base of the square. But if you put too much pressure on its sides—a lateral force like wind—the square will tilt and collapse on itself unless it is braced by supports. They include sheathing, typically plywood or oriented strand board OSB , to assure that the wall remains rigid even under lateral pressure.
This is how they assure that a structure will not be compromised by or suffer damage from wind. Shear walls must be engineered with the strength to transfer forces from each edge to the opposite edge, requiring calculations performed by a professional windstorm engineer. The forces on all four edges of a shear wall must balance each other.
A shear wall is determined by the location of the hold-downs. Most homes have external shear walls, but interior shear walls are typically found only in larger homes and large buildings located near coastal areas. Many custom homes have many windows, doors, bays, recesses, and open floor plans. These components and design do not provide adequate stability for the structure to withstand lateral loads as needed. Therefore, interior shear walls are often incorporated into home designs and construction plans to compensate for the many unique features incorporated into custom homes.
At Lynn Engineering, we understand construction in wood, steel, and concrete — and we are experts in design for coastal construction. Visit us at lynn-engineering. Shear Walls: What are they and how do they work?
You have shear walls, you have load-bearing walls, and you have architectural walls. While columns and load-bearing walls keep buildings standing up, carrying the compression load of the structure down to its foundation, the shear wall is what keeps structures from blowing over, resisting the lateral forces of wind and seismic activity. Understanding all the physics of shear walls may require an education in structural engineering, but a simple way to grasp how they operate is to imagine a wooden square with four edges—essentially two columns and two beams.
This frame can support weight from above—compression—as any load put on the upper beam is transferred through the columns to the base of the square. But if you put too much pressure on its sides—a lateral force—and the square will twist and collapse on itself unless it is braced by supports.
In turn, they assure that no wind will blow your house down. The support provided by shear walls does, however, create a design obstacle for architects. Almost all houses have external shear walls, but internal shear walls are typically found only in larger houses and high-rise buildings subject to lateral winds and seismic forces. The taller the building, the greater the need for internal shear walls and a lateral force resisting system.
As a general rule, the ideal placement for shear walls in high-rise buildings and those houses that require them is in the center of each half of a building. In other words, if there is a shear wall on its north side, it has to have an identical one on its south side. If there is a shear wall in the southeast corner of a building, then an identical shear wall will be placed on the opposite side of the central axis, in the southwest corner. Shear walls are typically identified on blueprints by a solid line with a thinner line indicating the sheathing that will cover it and which is usually then specified in a separate sheathing schedule.
Shear walls are one of many building components that are shown on architectural plans.
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