Steel beam twisting and bending, symbolizing lateral-torsional buckling.

Steel Beams Under Pressure: How to Prevent Lateral-Torsional Buckling?

Samir D’Costa in Tech & Innovation September 2025 • 4 min read.

"Unlock the secrets to robust construction! Discover how understanding and preventing elastic lateral-torsional buckling can ensure the stability of your cold-formed steel structures."

In modern construction, cold-formed steel beams are a popular choice for their lightweight nature and cost-effectiveness. However, their open cross-sections make them vulnerable to a phenomenon known as lateral-torsional buckling. This type of buckling occurs when the beam twists and bends sideways under load, potentially leading to structural failure. Understanding this instability is crucial for ensuring the safety and longevity of any steel structure.

Current design specifications, such as those provided by the American Iron and Steel Institute (AISI), offer equations to estimate the critical elastic lateral-torsional buckling stress. These equations primarily cater to symmetrical sections, leaving a gap in knowledge for non-symmetrical or custom-shaped beams. This is a problem because many contemporary designs incorporate unique shapes to meet specific application needs or optimize material use.

This article bridges that gap by diving into the mechanics of lateral-torsional buckling and offering comprehensive strategies to assess and prevent it, no matter the shape or orientation of the steel beams used. Whether you're an architect, engineer, or simply interested in structural integrity, this guide offers practical insights to reinforce your understanding and safeguard your projects.

What is Lateral-Torsional Buckling and Why Should You Care?

Steel beam twisting and bending, symbolizing lateral-torsional buckling.

Lateral-torsional buckling (LTB) is a mode of failure that can occur in beams subjected to bending. Unlike simple bending where the beam deflects vertically, LTB involves a combination of lateral displacement (sideways movement) and twisting (torsion). This is particularly relevant for cold-formed steel beams because their relatively low torsional stiffness makes them more susceptible to this type of instability.

Imagine a ruler standing on its edge. If you press down on the top, it will eventually buckle sideways and twist. That’s similar to what happens in lateral-torsional buckling. The compression flange of the beam (the part under compressive stress) tends to buckle laterally, and this buckling is coupled with a twisting of the entire section.

Here's why understanding LTB is essential:

Safety: Preventing structural failure is paramount. LTB can lead to sudden and catastrophic collapses, endangering lives and property.
Cost-Effectiveness: Designing against LTB from the outset can prevent costly repairs and retrofitting later on.
Design Optimization: A thorough understanding of LTB allows for more efficient use of materials, leading to lighter and more economical designs.
Code Compliance: Building codes and design specifications mandate consideration of LTB to ensure structural safety.

The factors influencing lateral-torsional buckling include the beam's length, cross-sectional shape, material properties, and the nature of the applied loads. Longer beams, sections with low torsional stiffness, and higher bending moments are all more prone to LTB.

Reinforce Your Structures Today

Understanding lateral-torsional buckling is not just an academic exercise; it's a practical necessity for anyone involved in the design and construction of steel structures. By grasping the fundamentals and implementing appropriate design strategies, you can ensure the stability and safety of your projects. Don't let unexpected instability compromise your constructions – take proactive measures to reinforce your designs and build with confidence.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.tws.2017.07.010, Alternate LINK

Title: Elastic Lateral-Torsional Buckling Of General Cold-Formed Steel Beams Under Uniform Moment

Subject: Mechanical Engineering

Journal: Thin-Walled Structures

Publisher: Elsevier BV

Authors: R.S. Glauz

Published: 2017-10-01

Everything You Need To Know

What is Lateral-Torsional Buckling (LTB) and how does it affect the stability of cold-formed steel beams?

Lateral-Torsional Buckling (LTB) is a mode of failure where a beam subjected to bending experiences a combination of lateral displacement (sideways movement) and twisting (torsion). This is particularly critical for cold-formed steel beams due to their relatively low torsional stiffness. Essentially, the compression flange of the beam buckles sideways, causing the entire section to twist. This instability can lead to structural failure, making it crucial to understand and prevent LTB in steel structures.

Why are cold-formed steel beams more susceptible to Lateral-Torsional Buckling compared to other types of steel beams?

Cold-formed steel beams are more prone to Lateral-Torsional Buckling because of their open cross-sections and inherent lower torsional stiffness. This means they are less resistant to twisting forces. Furthermore, the lightweight nature of cold-formed steel, while beneficial for cost-effectiveness and ease of use, can also contribute to a lower resistance to buckling compared to beams with different geometries or materials.

What are the key factors influencing Lateral-Torsional Buckling in steel beams?

Several factors influence Lateral-Torsional Buckling. These include the beam's length, which means longer beams are more susceptible; the cross-sectional shape, where sections with low torsional stiffness are more vulnerable; the material properties of the steel, which affects its resistance to buckling; and the nature of the applied loads, with higher bending moments increasing the risk of LTB. Understanding these factors is crucial for designing structures that can withstand LTB.

How can the understanding of Lateral-Torsional Buckling contribute to more cost-effective steel structure designs?

A thorough understanding of Lateral-Torsional Buckling allows for more efficient use of materials. By accurately assessing and preventing LTB, engineers can optimize designs to use less material while still meeting safety requirements. This can lead to lighter and more economical designs, reducing the overall cost of construction. Furthermore, preventing LTB from the outset avoids costly repairs and retrofitting that might be needed later.

How do current design specifications, like those from the American Iron and Steel Institute (AISI), address Lateral-Torsional Buckling, and what challenges remain?

Design specifications, such as those from the American Iron and Steel Institute (AISI), provide equations and guidelines to estimate the critical elastic Lateral-Torsional Buckling stress. However, these equations often cater primarily to symmetrical sections. A significant challenge remains in accurately assessing and preventing LTB in non-symmetrical or custom-shaped beams, which are increasingly common in modern designs. The article addresses this gap by exploring comprehensive strategies to evaluate and prevent LTB irrespective of beam shape or orientation, ensuring structural integrity in varied applications.