Strut vs Column

Both strut and column are ‘members’ or components of a structure. The structure can be a building, bridge, power pylon, cell base station tower (cell tower in short), or any civil engineering or mechanical engineering construction. In this article, we will explore the similarities, differences and other basic facts related to struts and columns, but we will not delve into specific theories of their structural design. Both strut and column are compression members, which means they take up compressive forces within the structure rather than the tensile forces. Struts can be found mainly in roof trusses, steel bridges, and other structures that incorporate trusses for their structural formation. Columns can be seen in buildings and similar type of structures, where the structure directly deals with the gravitational force. The materials used to construct these compressive members range from steel through concrete to timber.

What is a Strut?

Strut is an inclined compressive member or component of a truss type structure. The two ends of a strut are fixed to other members of the truss, and most of the time the purpose of the strut is to maintain the rigidity of the structure, which may be freely movable otherwise. Also, it is used for the purpose of adding more strength to the structure. A strut can be thought of as a long, inclined column. A specific value called “Slenderness Ratio” is defined, which determines whether the particular member falls into the category of Struts or into Columns. The higher the slenderness ratio is, more slender is the  structure element. If the slenderness is more, the structural element will fall into the category of struts, and the less slender ones will fall into the category of columns. Struts may fail due to buckling. This means that they bend off when compressed beyond a certain limit.

What is a Column?

Column is a thick compression member within a structure, and it fails due to compression rather than buckling. It fails, when the ultimate compressive strength of the material, which is the maximum compressive stress that the material can withstand, is exceeded. Columns are usually made of brittle materials, such as cast iron, concrete or stone, which are strong in compression. These materials are weak in tension. So, it is important to design the column in such a way that there is no tensile stresses involved, and the slenderness ratio of the column is less.

What’s the difference between a Strut and a Column?

1. Both Strut and Column are compression structural members.

2. Slenderness ratio of struts is high, whereas it is low for columns.

3. Struts fail due to buckling, but columns fail in compression.

Conclusion

Both of these structural elements are essential to the structural engineer in his design process, and the appropriate one must be used according to the particular situation.