Introduction to Flexural Beam Concept | Steel Structure | Lightboard

Summary

This video explores the behavior and application of bending beams in structural engineering. It explains how bending beams differ from tension and compression bars, highlighting their response to transverse loads, where the top experiences compression and the bottom undergoes tension. The video also covers the use of castellated beams, which offer increased load-bearing capacity and aesthetic appeal due to cutouts in the web. Additionally, it discusses the design process, emphasizing the importance of checking bending moments and shear forces to ensure the beam's strength meets ultimate load requirements.

Takeaways

• 😀 Balok lentur (bending beams) are different from axial force elements like compression and tension members, as they are loaded perpendicularly rather than axially.
• 😀 When a bending beam is loaded, the top part experiences compression and the bottom part experiences tension, which is a fundamental behavior of bending beams.
• 😀 Similar to compression members, bending beams can experience phenomena like buckling (for the compressed top part) and fracturing or fatigue (for the tensioned bottom part).
• 😀 In structural engineering, bending beams can be used as primary beams (balok induk) connecting columns or as secondary beams (balok anak) supported by primary beams.
• 😀 The most commonly used profiles for bending beams in steel structures are WF (Wide Flange) profiles, which have an 'I' or 'H' shape.
• 😀 Castellated beams are a unique type of bending beam that are often used in large-span structures, such as hangars and exhibition halls, due to their enhanced load-bearing capacity.
• 😀 Castellated beams are created by cutting and then rejoining a standard WF beam to form a longer beam, often with holes in the web, creating an artistic yet functional profile.
• 😀 The main advantage of castellated beams is that they offer increased load-bearing capacity compared to standard WF beams of the same material and volume, thanks to their increased height.
• 😀 Despite concerns, the holes in castellated beams do not weaken them significantly because the primary load-bearing function (bending moment) is handled by the flanges, not the web.
• 😀 In bending beam design, both bending moment and shear force need to be checked to ensure the beam can withstand the ultimate bending moment and shear force according to LRFD (Load and Resistance Factor Design) standards.

Q & A

What is the main topic of the video?

The main topic of the video is about the behavior of bending beams (balok lentur), the profiles commonly used for beams in the field, and the concept of castellated beams.

How does the behavior of a bending beam differ from axial-loaded members like compression and tension members?

Bending beams experience forces perpendicular to their axis, unlike compression and tension members, which experience axial forces. In a bending beam, the bottom experiences tension (stretching), and the top experiences compression (squeezing).

What happens when a bending beam is subjected to a transverse load?

When a bending beam is subjected to a transverse load, it bends. The bottom of the beam stretches and the top compresses, as evidenced by changes in the size of gaps on both sides of the beam.

What are the potential phenomena that may occur in a bending beam?

In a bending beam, the top may undergo buckling due to compression, while the bottom could experience fatigue or fracture under tension if the load is applied continuously.

What are the common applications of bending beams?

Bending beams are commonly used in structures as either primary beams (induk) that connect columns or secondary beams (anak) that rest on primary beams.

What is a castellated beam and why is it used?

A castellated beam is a type of beam made by cutting a solid beam (like a WF profile) into a pattern and then rejoining the pieces to create a longer, lighter beam with holes inside. It is used because it can carry more load with the same material, and it has the added benefit of allowing space for pipes.

How is a castellated beam made?

A castellated beam is made by cutting a solid beam along a pattern, typically a zigzag or honeycomb shape, and then shifting the cut pieces to form a longer beam. The pieces are then welded back together.

What are the advantages of castellated beams compared to regular beams?

Castellated beams have the same material volume as regular beams but can support more weight because their height is increased. They also have aesthetic appeal and can accommodate pipes through the holes in the middle.

What is the role of the holes in a castellated beam?

The holes in a castellated beam do not weaken it as might be assumed. These holes are designed to make the beam lighter and allow space for pipes or other utilities, without affecting the beam’s load-carrying capacity for bending or shear forces.

What are the key considerations when designing a bending beam for structural purposes?

When designing a bending beam, both the bending moment and shear forces need to be checked. The beam should be designed to withstand the ultimate bending moment and shear forces, with a safety factor incorporated according to design codes like LRFD.