A 7.3-Ton Steel Platform with a 150 mm Concrete Deck

English Version

Title: Steel Platform, 7,295 kg: HW350 Columns, HN400 Beams, 150 mm C30 Deck at +3.60 m

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Overview

A steel platform is a raised working floor inside a plant — built when a concrete mezzanine would be too slow or too heavy. This one is compact and standard: three hot-rolled H-sections, bolted beam-column joints, and a 150 mm concrete deck poured on top.

The drawing set covers the member schedule, one bolted joint detail, and the deck layout. Total steel: 7,295.80 kg.

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Member Schedule (from Drawing)

 

No.	Section	Weight (kg)	Grade	Standard
1	HM340×250	3,352.99	Q355	GB/T 11263-2017
2	HN400×200	1,928.39	Q355	GB/T 11263-2017
3	HW350×350	2,014.42	Q355	GB/T 11263-2017
Total		7,295.80

All three are hot-rolled H-sections — no welded built-up members, no custom plate girder work.

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Layout and Deck (from Drawing)

表格

Item	Value
Column grid	3,800 / 3,500 / 3,500 / 1,900 mm (one direction); 5,400 / 4,000 mm (the other)
Column section	HW350×350
Main beams	HN400×200
Secondary beams	HM340×250
Deck level	+3.60 m
Deck thickness	150 mm
Concrete grade	C30
Reinforcement	D@200 double layer, both directions

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Connection Detail (from Drawing)

 

Item	Value
Beam-column joint	Bolted, with −10 node plate
Bolts	M20, hole d = 22 mm
Bolt pattern	3 rows at 70 mm spacing
Node plate	−10 mm
Edge distances	47 / 48 mm

The beam end plate bolts to a −10 plate welded on the HW350×350 column. All field work is bolting — no site welding of the main frame.

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Advantages

Fast to build — three stock H-sections, bolted joints, one deck pour; a platform like this goes up in weeks.

Light structure, heavy deck — the steel frame carries 150 mm of concrete without a heavy concrete frame; the deck gives a solid, quiet floor.

Simple joints — M20 bolts through a −10 plate; easy to inspect, easy to tighten, no welder on site.

Standard sections, known cost — HW350, HN400, HM340 are all GB/T 11263 mill products; pricing and lead time are predictable.

Works with any finish — the concrete deck takes tiles, epoxy, or screed; the steel below stays open for services.

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Disadvantages / Limitations

Wet trades on a steel frame — the 150 mm deck needs formwork, rebar, and a curing period; the steel is fast, the concrete is not.

Dead load of the deck — 150 mm of C30 concrete adds roughly 3.6 kN/m²; the beams were sized for it, but later changes are limited.

Bolted joints are less stiff — under vibrating equipment, bolted beam-column joints can slip; a welded frame would be stiffer.

Fire protection — bare Q355 steel needs coating or board protection; the concrete deck helps the top side, not the beams.

Demolition is messy — removing a concrete deck from a steel frame means breaking concrete; a pure steel deck would be easier to relocate.

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Typical Use Cases

Equipment platforms in plants — a raised floor at +3.60 m for pumps, tanks, and process equipment.

Mezzanine storage floors — light-to-medium storage above workshop floor, with a concrete deck for forklift traffic.

Control rooms and offices inside plants — a solid floor for desks and cabinets above the production area.

Maintenance access levels — walking and working levels around tall equipment, with a 150 mm deck for tools and parts.

Small industrial buildings — compact 12 m × 9 m platforms where a concrete frame would be overkill.

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Fabrication and Erection Notes

Sections: HW350×350, HN400×200, HM340×250, Q355 — order per GB/T 11263-2017 and verify mill certificates.

Bolts: M20, hole d = 22 mm, 3 rows at 70 mm; check the −10 node plate weld before bolting.

Edge distances: keep the 47/48 mm bolt edge distances as drawn; do not shift holes on site.

Deck: 150 mm C30, D@200 double layer — set formwork on the steel beams, check the +3.60 m level before pouring.

Sequence: erect columns → beams → check level → bolt → lay deck formwork → rebar → pour → cure.

Coating: coat the steel before the deck is poured; protect the paint from concrete and water during construction.

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Bottom Line

A 7.3-ton steel frame plus a 150 mm concrete deck is the practical way to get a solid +3.60 m floor inside a plant. HW350 columns, HN400 beams, and M20 bolted joints do the structure; the C30 deck gives the quiet, hard surface that equipment and people need. Steel goes up in weeks — plan the concrete so the deck does not become the bottleneck

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**Email**: eddie@zdsteels.com, wells@zdsteels.com