Beams and columns, two whole building systems, are used to establish a safe load path that transfers the weight and forces on a structure to the foundations and the earth. Although they could be built from the same materials and shapes, beams and columns, have different designs and serve different functions.
Consider a balance beam used in gymnastics. It is a square 15 feet long and supported on both ends. Beams carry loads parallel to their longitudinal direction and are typically horizontal in shape. When a person is walking on a beam towards the middle of the span, their weight produces a vertical downward force that operates parallel to the longitudinal direction of the beam.
Beams support the weight of a building’s floors, ceilings, and roofs to transfer the load to a vertical load-bearing element of the structure. More powerful, heavier beams, called transfer beams, are sometimes used to hold the combined weight of stacked walls or other beams and transmit the load to the supports.
The design or sizing of beams requires an understanding of basic physics principles and engineering statics. A structural engineer is trained and fully equipped to check the loads acting on a beam, calculate the forces and stresses on it and choose the material, size, and shape accordingly. Part of the engineering consulting work I provide to my clients is the structural design of beams in new buildings and the restoration or strengthening of existing beams in a structure.
There is more flexibility when choosing the size and type of appropriate beams for a new project. The most frequently recommended materials to my clients are steel sections, reinforced concrete, grouted masonry, and beams made of wood. Although each material has benefits and drawbacks, its price, size, and fire rating are often considered.
When developing a new beam’s structural design or fixing an old one, I consider a few factors. Some of these factors are the amount of weight on the beam, its length or span, the precise height behind it or any restrictions imposed by geometry, the beam’s deflection limits, the material’s strength, and its fire rating and resistance. Similar factors are taken into consideration in the design of columns.
Columns are vertical structural components that carry weight parallel to the longitudinal axis by compression or tension. For example, visualize a rectangular table with four legs in each corner. The compression action of the legs on each item on the table distributes the table’s weight to the floor. In this case, the legs can be seen as columns.
Columns support the floor/roof beams and the floor above. The bottom floor columns of a tall building must support the entire weight of all the floors above. As a result, columns should ideally be positioned in the exact locations on each floor. This is not always possible, particularly in intricate architectural designs with diverse floor plans.
I typically suggest to customers in these circumstances to incorporate the structural design team early in the project so that they may collaborate with the architects to develop the best possible column plan.
When creating a column for a new structure, I take into account a few factors. Before choosing the material and size of the column, I weigh the weight of the floors or roof it supports. The height of the column has a considerable impact on the column’s total size. A column that supports 1000 pounds and is 10 feet tall might need to be twice as large as one that supports the same weight and is 20 feet tall. Everything will depend on the columns’ geometry and content.