21 Beam Sections for One Steel Frame: H750 Down to H250

English Version

Title: 21 Beam Sections, One Frame: H750×320×16×20 Down to H250×150×6×8

---

Overview

A steel frame is not one beam repeated. It is a family of sections: deep girders over long spans, mid-size beams at secondary gridlines, light beams under slabs. Get the family right and the frame is economical; over-specify one section everywhere and you pay for steel you do not need.

This project's schedule lists 21 beam types — 13 frame beams (GL) and 8 composite/secondary beams (GCL) — all in Q355B, running from H750×320×16×20 down to H250×150×6×8.

---

Frame Beams — GL Series (from Drawing)

 

Mark	Name	Section (H×B×tw×tf)	Grade	kg/m*
GL1	Frame beam	H700×320×12×20	Q355B	162.7
GL2	Frame beam	H400×200×8×12	Q355B	61.3
GL3	Frame beam	H500×220×10×14	Q355B	85.4
GL4	Frame beam	H600×250×10×14	Q355B	99.9
GL5	Frame beam	H500×200×8×12	Q355B	67.6
GL6	Frame beam	H700×280×12×16	Q355B	133.3
GL7	Frame beam	H600×220×10×12	Q355B	86.7
GL8	Frame beam	H750×320×16×20	Q355B	189.7
GL9	Frame beam	H300×180×6×10	Q355B	41.4
GL10	Frame beam	H700×250×12×14	Q355B	118.3
GL11	Frame beam	H650×220×12×14	Q355B	106.9
GL12	Frame beam	H700×270×12×16	Q355B	130.7
GL13	Frame beam	H650×250×12×14	Q355B	113.5

*kg/m calculated from the section dimensions at 7,850 kg/m³; the drawing gives sections only.

---

Composite and Secondary Beams — GCL Series (from Drawing)

 

Mark	Name	Section	Grade	kg/m*
GCL1	Steel-concrete composite beam	H500×200×6×8	Q355B	47.9
GCL2	Steel-concrete composite beam	H450×180×6×8	Q355B	43.0
GCL3	Secondary beam	H350×200×6×8	Q355B	40.9
GCL4	Steel-concrete composite beam	H600×220×6×10	Q355B	61.9
GCL5	Steel-concrete composite beam	H700×200×8×14	Q355B	86.2
GCL6	Secondary beam	H250×150×6×8	Q355B	29.9
GCL7	Steel-concrete composite beam	H700×280×8×14	Q355B	103.7
GCL8	Steel-concrete composite beam	H500×200×8×12	Q355B	67.6

---

Layout (from Drawing)

 

Item	Value
Plans	Beam layout plans at two levels
Grid	Axes ①–⑱ and Ⓐ–Ⓔ
Beam callouts	GL / GCL marks at each bay and gridline

---

What the Sections Tell You

• Depth tracks span. H750 for the long span, H600–H700 for the main frame lines, H300–H400 where spans are short or loads light.
• Flange thickness tracks moment. GL8 has 20 mm flanges at 320 wide; GL9 has 10 mm at 180 — four times the bending capacity, not four times the weight.
• Composite beams are thinner in the web. GCL sections run 6–8 mm webs against 10–16 mm on the GL beams; the concrete slab takes the compression, so the steel does less.
• One grade throughout. All 21 sections are Q355B — one steel to buy, one welding procedure, one set of consumables.

---

Advantages

1. Steel where it is needed — 21 sections instead of 3 means the deep beams carry the span and the light beams carry only the slab.
2. One grade — Q355B across the frame simplifies procurement, welding procedure, and inspection.
3. Composite option — the GCL series lets the slab work with the steel, cutting beam weight under floors.
4. Standard shapes — H-sections are familiar to every fabricator; detailing and connections follow normal practice.
5. Clear take-off — a marked schedule means the estimator, the shop, and the site all read the same list.

---

Disadvantages / Limitations

1. Many types to track — 21 marks means 21 nesting lists, 21 labels, and more chance of a beam going to the wrong bay.
2. Heavy sections are hard to handle — H750×320×16×20 at ~190 kg/m is a crane lift, not a two-man carry.
3. Composite beams need shear connection — the GCL series only works if the studs and slab are built as designed.
4. Welded sections need checking — deep webs at 12–16 mm need stiffeners and weld inspection; rolled availability varies by size.
5. Coordination load — beams, slab, and openings all compete for the same space; late changes hit several marks at once.

---

Typical Use Cases

1. Industrial and warehouse frames — main girders on the long spans, secondary beams between.
2. Multi-storey steel frames with concrete slabs — GCL composite beams under the floor.
3. Mezzanine and platform framing — mixed GL/GCL layout at one level.
4. Long-span roof structures — H700–H750 girders where deflection governs.
5. Frames with mixed loads — heavy equipment on part of the floor, light storage elsewhere.

---

Fabrication and Erection Notes

• Check each mark against the plan before fabrication; GL and GCL sections are not interchangeable.
• For welded sections, set camber on the deep girders (GL1, GL6, GL8, GL10, GL12) before welding.
• Stiffeners at load points and at the connections; follow the connection details, not the schedule alone.
• Composite beams: place shear studs before the slab; confirm stud layout with the deck drawing.
• Label every member with its mark at the shop and keep the label visible until it is erected.
• Sequence: main frame beams first, secondary beams second, slab last.

---

Bottom Line

21 sections, one grade, one frame. The schedule does the work a good design should: H750 where the span is long, H300 where it is short, 6 mm webs where the slab helps, 20 mm flanges where the moment is high. Buy one steel, cut it to the list, and label every piece — the frame goes together in the order the drawing says.

**WhatsApp**: +86‑13889862778, +86‑18242444407
**Email**: eddie@zdsteels.com, wells@zdsteels.com