Structural engineering has changed my world in a lot of ways, from building tall skyscrapers to building bridges that cross whole rivers.
The simple beam column is one of the most important parts of many of these buildings.
This part of the structure is subject to both axial load and bending moments caused by side forces or the eccentricity of the longitudinal load at the same time.
Many of the engineering marvels of today would not be possible without beam columns.
In this article, I'll look into beam columns and talk about what they are, how they work, and why they are important.
This post is for anyone, whether you're a new engineering student or a seasoned engineer who wants to learn something new.
So let's get started and find out what beam columns are and what they do.
Introduction
Formal definition:
A structural member is simultaneously subjected to axial load and bending moments produced by lateral forces or the eccentricity of the longitudinal load.
The beam column is an important part of engineering that is used to support buildings, bridges, and other structures.
In this article, we'll look at the different ways beam columns are used in engineering and in building projects.
What is a column beam?
A beam column is a structural member that is made to hold up against loads on its long axis.
It can be called a compression member, which means that most of the weight is put on it when it is compressed.
A beam column can hold the weight of beams, walls, slabs, and other structures.
Types of Beam Columns
There are many different kinds of beam columns used in engineering.
Rolled steel beam columns are a common type of column used in steel construction.
It is made by rolling steel plates into a shape that can hold loads when they are pressed together.
- Reinforced concrete beam column: This type of beam column is made of concrete and is strengthened with steel bars.
It is used to build with reinforced concrete and is a great way to move heavy things.
- Timber beam column: This type of beam column is made of wood and is often used in residential construction.
- Composite beam column: This type of beam column is made by combining two or more materials, like steel and concrete, to make a stronger and more durable structure.
Why settle for less when the beam column gives you everything?
Still hard to understand? Let me change the point of view a bit:
Are you sick of boring, straight beams that can only do one thing at a time? Don't look anywhere else but the beam column! Why use a simple, one-dimensional beam when you can use a member that does everything?
Yes, the beam column is the overachiever of structural engineering because it can easily handle both axial loads and bending moments.
So why choose just one kind of load when you can have them all? With the versatile beam column, you can embrace the oddness of the longitudinal load and add some lateral force to your life.
Okay, that was just a joke made to look like a TV ad.
Now let's go back to the explanation.
Materials Used in Beam-Columns
Beam-columns can be made from stone, wood, concrete, or steel, among other things.
In modern construction, however, H-shaped steel columns are often used because they are strong and stiff.
The H-shaped column's longer flange sides are thicker than the middle web piece, which makes it better able to resist compression forces.
Modern buildings are also often held up by beam-and-column systems made of reinforced concrete.
Definition and differences
Definition of Beam and Column
A beam is a piece of a building that is made to resist loads by bending.
Usually, it is flat and is held up at the ends or along its length.
Most floors, roofs, and bridges are held up by beams.
On the other hand, a column is a vertical part of a building that is made to resist mostly compressive loads.
It is usually used to hold up a building or other structure and move the weight to the foundation.
Differences between Beam and Column
There are a few main differences between beams and columns.
- Load carrying capacity: Beams are mostly made to carry loads that are bent, while columns are mostly made to carry loads that are compressed.
Because of this, beams tend to be stronger when bent and weaker when compressed, while columns tend to be stronger when compressed and weaker when bent.
- Orientation: Beams are usually on the side, and columns are usually on the top.
- Support conditions: Beams are usually supported at their ends or along their length, while columns are usually supported at their base and their top.
- Cross-sectional shape: Beams are usually square, circular, or I-shaped, while columns are usually square, circular, or rectangular.
Key Concepts and Differences
A beam column is a piece of a building that is made to handle both axial and bending loads.
It is used when heavy loads need to be moved from the structure to the foundation.
The beam column goes from the substructure to the superstructure.
It is a key part of moving weight from the top of the building to the foundation.
Differences between Beam Columns, Beams, and Columns
Here are the most important differences between beam columns, beams, and columns:
- Load carrying capacity: A beam column is made to carry both axial and bending loads, while a beam is mostly made to carry bending loads and a column is mostly made to carry axial loads.
A column is a vertical compression member, while a beam is a horizontal compression member.
A beam column connects the foundation to the top layer, which can be horizontal or vertical.
In terms of cross-sectional shape, a beam is usually square, circular, or I-shaped, while a column is usually square, circular, or rectangular.
A beam column's cross-section can be any shape, but it is usually a mix of square and round shapes.
- Usage: Beams are mostly used to support floors, roofs, and bridges, while columns are mostly used to support the weight of a building or other structure.
Beam columns are used in buildings that need to transfer both axial and bending loads to the foundation.
Beam-column connection
Beam-column connections hold beams and columns together in a structure.
In this article, we'll look at the different types of beam-column connections and how they help keep a building safe and stable.
Types of Beam-Column Connections
Based on how rigid the connection is, there are two main types of beam-column connections: flexible connections and rigid connections.
- Flexible Connection: In a flexible connection, which is also called a simple connection or a pinned connection, there is no transfer of moment between the parts that are connected.
It moves axial or shear forces, but not moments.
Flexible connections are often used in structures where the connections between beams and columns have to deal with small twists or turns.
- Rigid Connection: A rigid connection, also called a moment-resisting or fixed connection, transfers both shear and moment between the parts that are connected.
Rigid connections are used when the connection between a beam and a column has to handle big twists or twisting forces.
Special Connections
For crooked joints, eccentric beams to columns, and connections to column webs, simple connections can be used.
These connections are considered to be special.
By making the beam sections smaller, simple connections can have more resistance to being tied together.
This can be done by cutting holes in the web of the beam or by cutting away part of the beam's flanges (reduced web section).
Factors Influencing Beam-Column Connection Design
The type of beam-column connection used depends on a number of things, such as the amount of weight the structure can hold, the structural design requirements, and the properties of the materials.
Some of the things that affect how beam-column connections are made are:
- Load Capacity: The beam-column connection must have enough load capacity to hold up against the forces and moments that are likely to act on it.
- Requirements for Structural Design: The design of the beam-column connection must meet the building code and project specifications for structural design.
- Material Properties: The design must take into account the strength and stiffness of the materials used in the beam-column connection.
Maximum moment and design
In structural design, the ability of a structure to resist bending moments is a key part of making sure it stays stable.
Maximum Moment
Bending moment equations and formulas are used to figure out how much a beam can bend.
The maximum moment is the highest moment that a structure can have under a certain load case.
It is important to remember that the most important case for design may not always be the maximum moment.
Due to how bending and axial or torsion forces interact, a different load case with a lower value of moment may end up being reported as the most important case for design.
Design Moments
Design moments and maximum moments are not the same thing.
Design moments are figured out by looking at code requirements and safety factors, while maximum moments are figured out by looking at the results of an analysis.
The design moments take into account things like the properties of the material, safety factors, and combinations of loads based on what the code says.
Design moments are very important to make sure that the structure can handle the loads that are put on it and still has enough room for safety.
Consider the following things to figure out the design moment:
- Material Properties: When figuring out the design moment, the yield strength and modulus of elasticity of the beam are taken into account.
- Load Combinations: The design moment is figured out by using the building code's list of the different load combinations.
- Safety Factors: The design moment includes safety factors to make sure the structure can handle loads above and beyond the maximum expected loads.
Designing Beam Columns
Beam-columns are structural members that are both compressed along their length and bent across their width.
In buildings, they are used to move weight from the beam above to the foundation.
To design a beam-column, you have to figure out how much weight is on it and how big it is.
You can do this with software like Autodesk Inventor's Beam/Column Calculator or by hand using formulas from civil engineering textbooks or websites like CivilJungle.com or Civiconcepts.com.
Calculating loads on a beam-column
The first step in making a beam-column structure is to figure out how much weight is being put on the beam and column.
Most of the time, loads are put on columns at their ends, which causes axial compressive stresses.
Sometimes, axial forces, transverse forces, and bending moments can all act on a column (e.g., beam-columns).
By dividing the actual load distribution by the length of the beam, you can find the uniformly distributed load in kilonewtons per meter.
Calculating the size of the beam and column
After you figure out how much weight is on the beam-column, you need to figure out how big the beam and column need to be based on how much weight is on each.
For example, the volume of concrete for a 230mm x 450mm beam, excluding the thickness of the slab, would be 0.23 x 0.60 x 1 = 0.138 m3, and it would weigh 0.138 x 2400 = 333 kg.
In the same way, the total weight of a column whose length is usually three times its smallest cross-sectional width can be found by adding up the weights of all its parts.
Beam-Column Connection
A beam-column connection is where a beam and a column come together in a building.
It is made up of the joint and the parts of the beams, columns, and slab that are next to the joint.
Depending on how rigid the connection is, there are different types of beam-column connections.
A flexible connection, which is also called a simple or pinned connection, transfers shear or axial force but not moments.
A rigid connection, which is also called a moment-resisting connection or a fixed connection, moves both shear and moment between the parts that are connected.
For crooked joints, eccentric beams to columns, and connections to column webs, simple connections can be used.
Maximum Bending Moment
When an outside force is applied to a beam-column, causing it to bend and eventually break, that is when the bending moment is at its highest.
When pinned supports are used to hold up a continuous beam, hogging moments happen at the intermediate supports and sagging moments happen at the spans.
Very close to the intermediate supports are the points of contraflexure.
It is possible for the point of maximum moment to be where the larger primary moment is applied.
Design Moments and Maximum Moments
Design moments are figured out by looking at code requirements and safety factors, while maximum moments are figured out by looking at the results of an analysis.
When designing moments, many things are taken into account, such as the properties of the material, safety factors, and load combinations.
Maximum moments only take into account the loads that are put on a structure, not safety or code requirements.
Slenderness Ratio
In civil engineering, the slenderness ratio is the ratio between the length of a column and its smallest side dimension.
To figure it out, divide the column's effective length by its radius of gyration.
The slenderness ratio is used to figure out how much weight a column can hold before it bends.
If the slenderness ratio is less than or equal to 12, the columns are considered short.
If it is more than 12, the columns are considered long or skinny.
Short columns are controlled by their length and width, while long, thin columns are controlled by their ratios of length to width.
Beam/Column Joins
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Beam column uses
Bridges:
Beam columns are often used to build bridges because they can handle the bending moments caused by the weight of vehicles as well as the side forces caused by wind and earthquakes.
They can also be made to fit different spans and loads, which makes them a good choice for both short-span and long-span bridges.
Large, tall buildings:
Beam columns are often used in tall buildings because they can hold heavy weights and withstand the forces of wind and earthquakes.
They are also great for tall buildings because they can be made with different lengths and diameters.
This helps to spread the weight more evenly and makes the building more stable as a whole.
Industrial structures:
Because they can hold heavy equipment and machinery, beam columns are often used in industrial buildings like factories and warehouses.
In these kinds of buildings, beam columns are often used to support roof trusses and move weight from the roof to the foundation.
Residential structures:
Beam columns are also used in residential buildings, especially for the walls and foundations of basements.
They can also be used as support columns in open floor plans to help keep the upper floors stable.
Infrastructure projects:
Beam columns are frequently used in infrastructure projects like tunnels, dams, and retaining walls.
In tunnels, beam columns hold up the roof and walls.
In dams, they help spread the weight of the water evenly across the structure.
Beam columns can be used in retaining walls to stop the side forces that are caused by soil pressure and water.
Conclusion
As we wrap up our look at beam columns, it's clear that these building parts are very important in the world of engineering.
From the foundations of our buildings to the roads that connect our cities, beam columns give many of the structures we use every day the support and stability they need.
But beam columns are also interesting because they give us a unique look at how form and function work together.
How a beam column is made and put in place can have a big effect on how a building looks and feels as a whole.
Because of this, we can think of beam columns not only as useful tools, but also as an important part of engineering as an art and science.
So the next time you walk by a skyscraper or cross a bridge, take a moment to appreciate the simple beam column that helps make it all possible.
Links and references
Introduction to the Design of Steel Columns or Compression Members
