The geometry of a section of a shear wall and a column can be similar to the extent that the question of when a rectangular column becomes a wall often arises.
ACI 318-19, section 18.7.2.1, defines a column, for special moment frames, as having a minimum aspect ratio of 0.4. However, this condition is not the best criteria for considering column or wall design.
Construction constraints and the expected behavior of the element under loads are frequently used to decide whether an element should be designed as a wall or column.Â
A column has a large axial load and its shear response is similar to that of a beam, whereas a wall has a low axial load and its shear behavior is similar to that of a one-way slab.
Moreover, the area and distribution of longitudinal reinforcement and shear aspect ratio can be used to decide whether a rectangular column is designed as a column or as a shear wall.
Contents:
How to Distinguish Between Shear Wall and Column?
Longitudinal Reinforcement
Generally, longitudinal reinforcement requires lateral support to prevent buckling of steel bars under axial loads. If longitudinal reinforcement is required in a wall and its area is greater than 0.01Ag, the ACI 318-19, section 11.7.4.1, states that the longitudinal reinforcement should be laterally supported by transverse bars. This requirement can be used as criteria to decide whether the section should be designed as a wall or a column.
If the required longitudinal reinforcement area of the wall exceeds 0.01Ag, then a transverse tie should be provided at every intersection of longitudinal and transverse reinforcement, which is a laborious job to do. In this case, it is more practical to design the section as a column.
Shear Aspect Ratio
If the wall length-to-thickness ratio is equal to or greater than 6, then it is designed as a shear wall as its in-plane and out-plane shear behavior is easily known and distinctly different from the column.
If the aspect ratio ranges from 2.5 to 6, the element is designed as a shear wall or column, based on the shear force and the direction of the shear force. For the aspect ratio less than 2.5, the member is most likely to be designed as a column.
FAQs
A column has a large axial load and its shear response is similar to that of a beam, whereas a wall has a low axial load and its shear behavior is similar to that of a one-way slab. Moreover, the area and distribution of longitudinal reinforcement and shear aspect ratio can be used as a criterion to decide whether a rectangular column is designed as a column or as a shear wall.
Construction constraints and expected behavior of the element under loads are mostly used to decide whether an element should be designed as a wall or a column.
Longitudinal reinforcements are the RC column's main bars, placed in square, rectangular, or circular patterns. The purpose of longitudinal reinforcement is to assist concrete in resisting imposed loads. For more information, please click here.
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