Tapered H Beam : Variable Depth 800→930 mm, Q355B, 

Tapered (variable-depth) H beams are welded built-up sections where beam height changes along the span — deeper at supports where moment is highest, shallower mid-span where it is not. Below is member GL3-2 from an actual fabrication drawing.

Basic Specs

Section Composition

The beam is a tapered welded H section:

Beam depth increases from 800 mm at left to 930 mm at right, matching the bending moment diagram.

Advantages

1. Material efficient — deeper only where needed; saves 15–25% steel vs uniform deep section
2. Lower self-weight — lighter beam reduces column and foundation loads
3. Matches moment diagram — section depth follows bending moment, no wasted material
4. Clearance friendly — shallower mid-span provides more headroom
5. Custom fabrication — any depth profile possible, tailored to project loads

Disadvantages / Limitations

1. Higher fabrication cost — tapered web requires cutting and welding, more labor
2. Not standard mill product — must be shop-fabricated, longer lead time
3. Complex connections — tapered ends need custom end plates and bolt layouts
4. Web buckling risk — thinner web at shallow sections needs stiffener design
5. Not reversible — cut to specific span, cannot be reused elsewhere easily

Typical Applications

1. Portal frame buildings — rafter beam of single-slope or multi-span factory
2. Long-span warehouses — 15–30 m span where mid-span depth can be reduced
3. Canopy & porch structures — tapered rafter for sloped roof appearance
4. Bridge girders — small span road/rail bridge where haunched supports needed
5. Industrial platform beams — where headroom varies along the span
6. 

Fabrication Notes

• Web cut by CNC plasma/oxy-fuel to tapered profile
• Flange welded to web by automatic submerged-arc welding
• Stiffeners placed at supports and load points
• End plates welded, drilled for bolted connection
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