Shear Walls
Shear Walls 17
3
SHEAR WALLS by Timothy P. McCormick, P.E.
Seismic Retrofit Training
18
Shear Walls
Seismic Retrofit Training
Shear Walls 19
SHEAR WALLS
This section provides an introduction to shear walls and how they resist earthquake and wind forces. This section also shows how to properly construct the shear walls and the parts that make them up. With this knowledge, contractors can build proper shear walls and inspectors can recognize the errors untrained contractors make.
GETTING THE BIG PICTURE
WHAT IS A SHEAR WALL?
Shear walls are vertical elements of the horizontal force resisting system. They are typically wood frame stud walls covered with a structural sheathing material like plywood. When the sheathing is properly fastened to the stud wall framing, the shear wall can resist forces directed along the length of the wall. When shear walls are designed and constructed properly, they will have the strength and stiffness to resist the horizontal forces. (Fig. 3.1)
Fig.3.1 - Typical Shear Wall
WHERE SHOULD SHEAR WALLS BE LOCATED?
Shear walls should be located on each level of the structure including the crawl space. To form an effective box structure, equal length shear walls should be placed symmetrically on all four exterior walls of the building. Shear walls should be added to the building interior when the exterior walls cannot provide sufficient strength and stiffness or when the allowable span-width ratio for the floor or roof diaphragm is exceeded. For subfloors with conventional diagonal sheathing, the span-width ratio is 3:1. This means that a 25-foot wide building with this subfloor will not require interior shear walls until its length exceeds 75 feet unless the strength or stiffness of the exterior shear walls are inadequate. (Fig. 3.2)
Seismic Retrofit Training
20
Shear Walls
Fig.3.2 - Location of Shear Walls Shear walls are most efficient when they align vertically and are supported on
3
SHEAR WALLS by Timothy P. McCormick, P.E.
Seismic Retrofit Training
18
Shear Walls
Seismic Retrofit Training
Shear Walls 19
SHEAR WALLS
This section provides an introduction to shear walls and how they resist earthquake and wind forces. This section also shows how to properly construct the shear walls and the parts that make them up. With this knowledge, contractors can build proper shear walls and inspectors can recognize the errors untrained contractors make.
GETTING THE BIG PICTURE
WHAT IS A SHEAR WALL?
Shear walls are vertical elements of the horizontal force resisting system. They are typically wood frame stud walls covered with a structural sheathing material like plywood. When the sheathing is properly fastened to the stud wall framing, the shear wall can resist forces directed along the length of the wall. When shear walls are designed and constructed properly, they will have the strength and stiffness to resist the horizontal forces. (Fig. 3.1)
Fig.3.1 - Typical Shear Wall
WHERE SHOULD SHEAR WALLS BE LOCATED?
Shear walls should be located on each level of the structure including the crawl space. To form an effective box structure, equal length shear walls should be placed symmetrically on all four exterior walls of the building. Shear walls should be added to the building interior when the exterior walls cannot provide sufficient strength and stiffness or when the allowable span-width ratio for the floor or roof diaphragm is exceeded. For subfloors with conventional diagonal sheathing, the span-width ratio is 3:1. This means that a 25-foot wide building with this subfloor will not require interior shear walls until its length exceeds 75 feet unless the strength or stiffness of the exterior shear walls are inadequate. (Fig. 3.2)
Seismic Retrofit Training
20
Shear Walls
Fig.3.2 - Location of Shear Walls Shear walls are most efficient when they align vertically and are supported on