Differences Between I-Beams and H-Beams

Release Time:

08 Jul,2024

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Introduction to I-Beams

I-beams have an "I" shaped cross-section, with the inner surface of the flanges inclined, typically at a 1:6 ratio. This design makes the flanges thicker on the inside and thinner on the outside, leading to different cross-sectional characteristics in the two main planes. Due to this structure, I-beams have limited torsion resistance. Even with the introduction of thicker I-beams, this structural weakness remains.

Introduction to H-Beams

H-beams are widely used in modern steel structures. Unlike I-beams, H-beams have parallel upper and lower surfaces and no inclination on the inner surface of the flanges. This gives H-beams significantly better cross-sectional characteristics than traditional I-beams, channel steels, and angle steels. Named for their "H" shaped cross-section, H-beams have an optimized area distribution and a more favorable strength-to-weight ratio. The straight inner edges of H-beams simplify welding and splicing, saving materials and construction time.

Comparison and Usage

Structural Dimensions:
- I-beams, whether ordinary or light, have high and narrow cross-sectional dimensions, resulting in a significant difference in the moment of inertia of the two main sleeves. This limits their use to members bent in the web plane or lattice-type load-bearing members. They are not suitable for axially compressed members or those bent perpendicular to the web plane.
- H-beams, being efficient and economical, have widened flanges and parallel inner and outer surfaces, allowing easy connection with high-strength bolts. They come in a range of sizes, making them versatile for design and selection.
Manufacturing Differences:
- I-beams are all rolled sections with a flange inner edge slope of 1:10 due to production limitations.
- H-beams are rolled with both horizontal and vertical rollers, resulting in wider flanges without slopes. This requires a more complex rolling process and equipment. The maximum height for rolled H-beams in China is 800mm, beyond which they must be welded.
National Standards:
- China's national standard (GB/T11263-1998) categorizes H-beams into narrow flange (hz), wide flange (hk), and steel piles (hu). Narrow flange H-beams are suited for beams or compression-bending members, while wide flange H-beams and piles are for axially compressed or compression-bending members.
Force Resistance:
- I-beams have small side lengths and large heights, resisting force in only one direction.
- H-beams, with deep grooves and large thickness, can withstand forces in two directions.
Application in Construction:
- I-beams are limited to use as beams due to instability when used as load-bearing columns.
- H-beams can be used for both beams and load-bearing columns, making them more versatile in steel structure buildings.
Mechanical Properties:
- H-beams have better mechanical properties and are more economical than I-beams. With wider flanges, H-beams offer greater lateral stiffness and bending resistance, and they are lighter in weight under the same specifications.
Flange Thickness:
- I-beams have flanges that are thicker near the web and thinner outside.
- H-beams have equal flange thickness throughout.
Types of H-Beams:
- HW, HM, HN, and H are general types of H-shaped steel. HW, HM, and HN are hot-rolled, while H is welded.
- HW: Equal height and flange width, used for steel core columns in reinforced concrete frames.
- HM: Height to flange width ratio of 1.33~1.75, used in steel structures as frame columns or beams.
- HN: Height to flange width ratio of ≥2, mainly used for beams.

In conclusion, while both I-beams and H-beams have their advantages and specific uses, H-beams offer better structural performance, versatility, and ease of use in construction.