Lecture 3 ARC

1.

Architecture of Industrial Buildings
Lecture 3
Steel Frame of Single-Storey Buildings
Columns, crane girders, roof trusses, bracing, and the erection joints that tie a steel-framed industrial building
together

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CHAPTER 2 — STEEL FRAME
Seventeen Sheets, Six Building Blocks
1
2.01 – 2.02
Steel columns
2
2.03 – 2.04
Crane girders & rails
Girder cross-sections, rail types, and how the girder is fixed to the column so the crane can run.
3
2.05
End-wall frame
Fachwerk columns and horizontal wind trusses that close the building's gable end and carry wind load down.
4
2.06 – 2.11
Roof trusses & decking
5
2.12 – 2.14
Bracing systems
6
2.15 – 2.17
Conveyor-line erection
STEEL STRUCTURES · CHAPTER 2 — STEEL FRAME OF SINGLE-STOREY BUILDINGS
Constant-section columns for craneless or lightly loaded bays; two-branch columns for heavier cranes and
taller bays.
Two truss families (1.5% and 1:3.5 top-chord slope), sub-truss trusses, purlins, and the main erection joints
that tie it all to the column.
Vertical column bracing and horizontal truss bracing that keep the frame stable along its length.
Whole roof sections pre-assembled on the ground and lifted into place as one block — plus a full building
example.
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1
2.01 – 2.02
Two Families of Steel Column
• Constant-section columns serve craneless buildings or ones with light suspended cranes: a single welded I-shaft runs the full
height, its web deepening from 400 mm to 630 mm as the building gets taller.
• Two-branch columns take over once overhead cranes of real capacity are involved (10–50 t and up, in bays 10.8–18.0 m
tall): the shaft splits into an under-crane neck above and a lattice, double-branch trunk below.
• The two branches — an outer, exposed one and an inner, under-crane one — are tied by a two-plane lattice of rolled angles,
with a solid diaphragm every four panels to keep the section from twisting.
• Column base, crane-corbel level, and cap are all standardized connection points, so the same family of parts recurs whether
the column is 7.2 m or 18 m tall.
Figure 1. Exploded view of a two-branch column:
cap and crane-corbel level at top, lattice trunk
below, base at bottom.
STEEL STRUCTURES · CHAPTER 2 — STEEL FRAME OF SINGLE-STOREY BUILDINGS
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4.

1
2.01
Setting the Column Base
• The column base bears directly on the foundation pedestal through an anchor (base) plate, bedded on a
layer of grade-400 cement mortar that takes up any unevenness in the concrete.
• Anchor bolts, cast into the pedestal beforehand, pass through the base plate and are torqued down once
the column has been plumbed.
• Erection follows one of two methods: 'surveyed' installation, where each column is checked and adjusted
with geodetic instruments, or the faster 'survey-free' method, where a fixing jig on the crane sets the
column precisely without a separate check.
• Increasingly, survey-free erection is preferred: the base plate is machined and pre-set on the foundation,
so the column simply lands in its final position as the crane sets it down.
Figure 2. Column base on its foundation pedestal: anchor
bolts and base plate, bedded on cement mortar, transfer the
full column load into the concrete below.
STEEL STRUCTURES · CHAPTER 2 — STEEL FRAME OF SINGLE-STOREY BUILDINGS
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2
2.03
Crane Girders and the Rails They Carry
• Crane girders come in two arrangements: split (razreznye), simply supported on each column Girder height by column spacing and crane capacity
and jointed over the support, or continuous (nerazreznye), lighter but harder to transport and
Column spacing
Crane capacity
Girder height at
erect.
support
• Cross-section is a welded I with flanges of equal or expanded width; web stiffeners are
spaced at 1.5 m intervals, sized 90×6 mm up to 1.1 m of girder height and 120×8 mm above
it.
• A rank-and-file girder for 6 m column spacing and cranes up to 50 t is a standard, catalogued
design — one of the most frequently repeated elements on the whole sheet set.
• Two rail families run on top: railway-type rails (P-38, P-43) for lighter cranes, and dedicated
crane rails (KR-50 up to KR-140) for heavier ones — the number in the mark is the head width
in millimetres.
6m
≤ 20 t
0.8 m
6m
30 – 50 t
1.3 m
12 m
any (above)
+0.3 m more
1.5 m
stiffener spacing along the girder web
KR-50 → KR-140
crane-rail range, by head width in mm
STEEL STRUCTURES · CHAPTER 2 — STEEL FRAME OF SINGLE-STOREY BUILDINGS
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6.

2
2.04
Fixing the Crane Girder to the Column
• The girder end sits on a machined bearing corbel projecting from the column and is bolted down, but the
connection still has to let the girder move.
• A flexible stop-plate (gibkaya planka) and a bearing gusset fix the girder's vertical plane while still
permitting it to shift lengthwise as steel expands and contracts with temperature.
• Stop angles bolted to the column — never welded to it — keep the girder centred; because they aren't
welded, the girder's top can still creep slightly along its own axis without stressing the column.
• At the building's end wall, a dedicated end stop absorbs the crane's bumper impact, so the last girder
span needs a heavier fixing than a typical intermediate one.
Figure 3. Crane-girder-to-column joint: a flexible stop-plate and
bearing gusset fix the girder's vertical plane while still allowing
lengthwise thermal movement.
STEEL STRUCTURES · CHAPTER 2 — STEEL FRAME OF SINGLE-STOREY BUILDINGS
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3
2.05
Closing the Gable End
• The end (gable) wall carries its own lightweight fachwerk columns — welded I-shafts spaced independently of the main
frame — because wind on the gable acts in a different direction than wind on the long walls.
• Wind load on the gable is collected by these fachwerk columns and handed off to horizontal wind trusses at crane-rail level
and at the eaves, which span between the building's main columns.
• The crane-rail-level wind truss does double duty: it also carries a fenced repair platform, so maintenance crews can reach
the crane without extra scaffolding.
• Fachwerk column heads are set to match the roof truss geometry above them, so the gable framing stays flush with the
main structural grid even though its columns are independent of it.
Figure 4. End-wall elevation: the fachwerk column and
the horizontal wind truss at crane-rail level, which
doubles as a fenced crane-repair platform.
STEEL STRUCTURES · CHAPTER 2 — STEEL FRAME OF SINGLE-STOREY BUILDINGS
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4
2.06 – 2.10
Two Families of Roof Truss
• Trusses with a 1.5% top-chord slope (sheets 2.06/2.07) use a nearly flat roof and are decked with
steel profiled sheet or ribbed RC slabs; sub-truss (podstropilnye) trusses let the main trusses land
on a 12 m grid while the roof itself runs on a 6 m rhythm.
• Trusses with a steeper 1:3.5 slope (sheets 2.09/2.10) suit unheated buildings roofed in corrugated
asbestos-cement sheet, where rainwater run-off matters more than a flat, walkable deck.
• Both families are built from hot-rolled angle sections for spans of 18, 24, 30, and 36 m, with shop
joints (welded) and erection joints (bolted) tabulated on the sheet for every span.
Truss span vs. approximate height at midspan
Span
1.5% slope family
1:3.5 slope family
18 m
≈ 2.65 m
≈ 3.15 m
24 m
≈ 3.15 m
≈ 3.75 m
30 / 36 m
≈ 3.75 – 4.15 m
n/a
• Where a truss's top-chord panel exceeds 127 mm, an extra bracing rule kicks in — a reminder that
these are catalogued designs with built-in limits, not freely scalable shapes.
Sub-truss trusses (podstropilnye)
Span 12 m between main columns; let the roof trusses above
keep their economical 6 m rhythm without doubling the number
of main columns beneath them.
STEEL STRUCTURES · CHAPTER 2 — STEEL FRAME OF SINGLE-STOREY BUILDINGS
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4
2.08
The Frame's Main Erection Joints, in One View
• This composite view gathers the frame's key bolted joints in one place: column base on its concrete
foundation, crane girder on its bearing corbel, and roof truss on the column cap.
The column base is not welded to the foundation — it bears on cement mortar and is held down by anchor
bolts, so the joint can absorb minor construction tolerances without cracking the concrete.
The crane girder's connection allows its top to creep slightly along the column axis, since the stop angles
that centre it are bolted, not welded, to the column flange.
At the cap, the roof truss and sub-truss bear on a machined, planed bearing rib and are through-bolted —
the same detail recurs at every column in the building, which is what makes site erection fast and
repeatable.
Figure 5. Main erection joints of the steel frame: column base, cranegirder bearing, and roof-truss cap connection, shown together on one
column line.
STEEL STRUCTURES · CHAPTER 2 — STEEL FRAME OF SINGLE-STOREY BUILDINGS
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4
2.11
Purlins and Decking on Tube-Truss Roofs
• For roof trusses welded up from electrically-welded steel tube, purlins land directly on the top chord and
are fixed with self-tapping bolts — one bolt per wave at the ridge and hip purlins, one every fourth wave
at intermediate purlins.
• The steel profiled decking runs over the purlins, lapped and fastened the same way, with cover strips over
the self-tapping bolts to keep the roof watertight.
• An 'end-of-run' (endovny) purlin and matching cover plates handle the joint where two decking runs meet,
so the waterproofing detail doesn't depend on a single continuous sheet.
• The sub-truss (podstropilnaya) truss again lets the main roof trusses sit on a 6 m rhythm while the cranesupporting columns below stay on a wider 12 m grid.
Figure 6. Purlins and profiled steel decking erected on a tube-truss
roof, bearing on the sub-truss truss and the main column below.
STEEL STRUCTURES · CHAPTER 2 — STEEL FRAME OF SINGLE-STOREY BUILDINGS
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5
2.12 – 2.14
Bracing: Keeping the Frame Stable Lengthwise
• A single row of columns and trusses is stable across the building's width, but needs help staying stable along its
length — that job belongs to bracing (svyazi).
• Vertical bracing between columns is placed in the end bays of each temperature block, in V-shaped or cross
(crossed-rod) patterns, and is doubled at crane-girder level in two-branch columns to brace both branches.
• Horizontal bracing at the top and bottom chords of the roof trusses ties adjacent trusses together, so wind or
crane surge loads on one truss are shared with its neighbours instead of acting alone.
• For two-branch columns, crane-level bracing is built as crossed rods in two planes — one for each branch —
anchored to base plates that are themselves tied into the foundation to resist the horizontal pull.
Figure 7. Crossed-rod bracing between the branches of a
two-branch column, anchored to base plates tied into the
foundation below.
STEEL STRUCTURES · CHAPTER 2 — STEEL FRAME OF SINGLE-STOREY BUILDINGS
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6
2.15 – 2.16
Assembling Whole Roof Blocks on the Ground
• Instead of erecting a truss, purlins, and decking piece by piece at height, whole roof sections are preassembled at ground level on a conveyor line, then lifted into place as one finished block.
A typical block combines two crane girders (tied by a bracing beam and diagonal ties near the supports),
a sub-truss truss, a roof truss, purlins, and the decking — four standard block variants cover both plain
and skylighted (fonar) bays.
Blocks are lifted by the building's own crane bridge where one is already installed, or by mobile or tower
cranes moving along the building's length where it isn't.
The benefits are the ones any prefabrication strategy promises: better quality control at ground level,
faster overall erection, and less work performed at height.
Figure 8. Conveyor-line block erection: a fully assembled roof section, with
its crane girders, sub-truss truss, and decking, is lifted into place by the crane
bridge.
STEEL STRUCTURES · CHAPTER 2 — STEEL FRAME OF SINGLE-STOREY BUILDINGS
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2.17 — WORKED EXAMPLE
One Building, Assembled from These Parts
Designed by the Leningrad institute Promstroyproekt for an aluminium-structures plant, on a 30×12 m column grid — every system in this chapter, in one section.
The roof is carried on prismatic tube trusses (a triangular, equilateral cross-section) that bear directly under the fonar (skylight) frames without a separate transfer structure.
Roof build-up, weather side down: gravel in bitumen, roofing felt, vapor barrier, foam-polystyrene insulation, profiled steel decking — and a triangular fonar that sheds about
25% less roof area to glazing than a taller, rectangular one.
Figure 9. General view of a 30×12 m building section: prismatic tube trusses, purlins, and
profiled decking, with the triangular fonar at the ridge.
STEEL STRUCTURES · CHAPTER 2 — STEEL FRAME OF SINGLE-STOREY BUILDINGS
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14.

★
RECAP
From Base Plate to Finished Roof
1
2
3
Columns & girders
Roof & bracing
Conveyor erection
Constant-section or two-branch columns carry
the crane girders that ride on standard rail
types — every joint bolted, none welded, so
the frame can move as it heats and cools.
Two truss families roof the building;
horizontal and vertical bracing then ties the
whole frame together along its length so it
stands as one stable structure.
Ground-level pre-assembly turns dozens of
small connections into a handful of crane lifts
— the same design family scales from a single
bay to a full building.
Every connection in this chapter answers the same question: how does load move from the roof, through the column, into the ground — while still letting steel
expand, contract, and go up fast?
STEEL STRUCTURES · CHAPTER 2 — STEEL FRAME OF SINGLE-STOREY BUILDINGS
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