PLATE GIRDER DESIGN • IS 800:2007 • INDIA
Plate Girder Design Guide for Industrial and Infrastructure Projects in India
Quick Answer
A plate girder is a built-up flexural member with steel web and flange plates welded into an I or box section, designed per IS 800:2007 for spans and loads beyond rolled beam capacity — used in bridge superstructures, crane runways, long-span industrial buildings, pipe bridges and heavy process plant structures across India.
Key Takeaways
- Plate girder design sizes web and flange plates for bending, shear and deflection under IS 875 load cases, checked per IS 800:2007 limit state clauses.
- Web plates resist shear; flange plates resist bending moment — stiffeners prevent local buckling at supports and along the span.
- IS 2062 E350 is common for heavy industrial and bridge girders; E250 applies to lighter spans where stress levels permit.
- Girder depth is typically span/10 to span/15 for buildings and span/8 to span/12 for bridges — final depth from deflection and shear checks.
- Welded plate girders dominate Indian practice; bolted splices connect shop-fabricated modules at site.
- Design errors — slender unstiffened webs, wrong grade, ignored bearing stiffeners — cause costly fabrication rework or field failures.
- Suncorporation Fabricators & Engineers executes approved plate girder shop drawings from our Hyderabad workshop for industrial and infrastructure projects nationwide.
Structural engineers, bridge designers, EPC contractors and PMC teams specifying structural steel plate girder systems in India need a clear design-to-fabrication reference aligned with IS 800 plate girder design practice and IS 875 loading rules. This guide covers plate girder design principles, component detailing, material grades, inspection requirements and application contexts — as an engineering authority resource. For workshop scope, tonnage and delivery, see the separate plate girder fabrication product page.
What is a Plate Girder?
Answer: A plate girder is a fabricated steel beam built from flat plates — a vertical web plate welded to horizontal top and bottom flange plates — forming an I-section or box section that carries bending and shear over long spans.
Unlike rolled sections (ISMB, ISWB) produced in steel mills, fabricated plate girders are custom-proportioned in depth, flange width and plate thickness to match the exact moment and shear envelope on a bridge, crane runway or industrial frame. In India, plate girder sections are almost always welded steel girders shop-assembled per approved drawings, with field bolted or welded splices.
Plate girders are a subset of built-up beam construction but the term is reserved for flexural members where the web is a plate element requiring stiffener design — distinct from light built-up purlins or truss chords.
Why Plate Girders Are Used
Answer: Plate girders are used when rolled beams cannot provide required span, depth flexibility, load capacity or camber control economically.
- Long spans: Warehouse and long span steel girders beyond 12–15 m rolled beam practicality
- Heavy loads: EOT crane runways, gantry paths and bridge superstructures
- Custom depth: Headroom constraints in plants; depth matched to shear at supports
- Weight optimisation: Variable flange thickness along span in bridge girders
- Camber control: Pre-set upward curvature for dead load compensation
Components of a Plate Girder
Answer: A plate girder comprises web plate, top and bottom flanges, and stiffeners — each sized for a specific structural function per IS 800:2007.
Plate Girder Components Table
| Component | Function | Typical Detail |
|---|---|---|
| Web plate | Resists vertical shear; connects flanges | 6–20 mm plate; may be stiffened |
| Top flange | Resists compression (or tension in uplift cases) | Wider plate; may taper in bridges |
| Bottom flange | Resists tension under sagging moment | Often thicker than top in simple spans |
| Bearing stiffeners | Transfer reactions; prevent web crippling at supports | Full-depth plates welded to web |
| Intermediate stiffeners | Increase web buckling resistance between supports | Vertical plates at calculated spacing |
| End connection plates | Bolted or welded support/splice interfaces | Per connection design IS 800 Ch. 10 |
| Weld seams | Join web to flanges | Full-penetration or fillet per design |
Web Plate
Answer: The web plate carries most of the vertical shear force and must be checked for shear buckling, crippling at concentrated loads and interaction with bending per IS 800 Clause 6.7.
Web depth d sets overall girder depth. Slenderness ratio d/tw determines whether intermediate stiffeners are mandatory. Thin deep webs without stiffeners fall into the slender classification and lose shear capacity.
Flanges
Answer: Flange plates resist the flange force Ff = M/z from bending moment; width and thickness control local buckling classification under IS 800 Table 2.
Industrial girders often use constant flange size over the full span. Bridge steel girders may use haunched or tapered flanges where moment envelope varies significantly.
Stiffeners
Answer: Stiffeners are plate elements welded perpendicular to the web to prevent local buckling, distribute concentrated loads and provide torsional restraint to compression flanges.
Bearing Stiffeners
Bearing stiffeners are placed at support points and under concentrated wheel loads (crane girders). They transfer bearing reactions into the web and down to the support, checked for buckling as columns over a length b1 per IS 800. Missing bearing stiffeners at crane wheel positions is a frequent design omission on industrial programmes.
Intermediate Stiffeners
Intermediate stiffeners divide the web panel into smaller aspect ratios, restoring shear buckling capacity. Spacing follows IS 800 limits based on web slenderness and transverse stiffener requirements. They may be nominal (providing restraint) or load-bearing where intermediate point loads apply — such as cross-beam connections on pipe rack girders.
Plate Girder Design Principles
Load Transfer Mechanism
Answer: Applied loads create bending moment and shear along the span; flanges develop couple forces to resist moment while the web resists shear — reactions concentrate at bearing stiffeners into supports.
- Uniform distributed load → parabolic moment, linear shear
- Concentrated crane wheel load → local web crippling check at stiffener
- Lateral load on top flange → lateral-torsional buckling check with restraint from deck or bracing
Bending Behaviour
Answer: Bending capacity follows IS 800 Section 8 — plastic moment capacity Md for compact sections; reduced capacity for semi-compact or slender flanges/web in combined bending and shear.
Section classification (plastic, compact, semi-compact, slender) depends on flange outstand b/t and web d/tw ratios against Table 2 limits for internal elements in compression.
Shear Behaviour
Answer: Shear resistance Vd uses web area d × tw with reduction for web buckling when stiffeners are absent or web is slender per IS 800 Clause 6.7.
High shear at supports often governs web thickness in short heavy spans — not bending at mid-span.
Deflection Control
Answer: Serviceability deflection limits per IS 800 Table 5 and project specifications — commonly span/300 for floors, span/600 for crane girders, span/800 for sensitive equipment supports — checked under IS 875 SLS load combinations.
Plate Girder Design Process
Answer: Design proceeds from load definition through preliminary sizing, section classification, ULS checks, SLS deflection, stiffener detailing and connection design before shop drawing issue.
- Define loads per IS 875 Structural Design Loads Guide — DL, LL, wind, crane (IS 807)
- Structural analysis for moment, shear and deflection envelopes
- Preliminary depth (span ratio) and flange/web trial sizes
- ULS checks: bending, shear, combined M-V, LTB with restraint conditions
- Stiffener design — bearing at supports, intermediate spacing
- SLS deflection and vibration (crane girders)
- Connection and splice design; camber specification
- Issue GA and design brief for structural steel detailing
Design Parameters Table
| Parameter | Reference | Typical Value / Note |
|---|---|---|
| Design code | IS 800:2007 | Limit state design |
| Loads | IS 875 Parts 1–3 | DL, LL, wind combinations |
| Material | IS 2062 | E250 / E350 / E450 |
| γm0 (material factor) | IS 800 Table 4 | 1.10 |
| Deflection limit (floor beam) | IS 800 Table 5 | Span/300 |
| Deflection limit (crane girder) | IS 807 / project spec | Span/600–800 |
| Web slenderness limit | IS 800 Table 2 | Classifies stiffener need |
| Camber | Project specification | Dead load offset; set in shop |
Span vs Girder Depth Table (Preliminary — Industrial & Building)
| Span (m) | Typical Depth (mm) | Span/Depth Ratio | Common Application |
|---|---|---|---|
| 8–12 | 600–900 | 12–15 | Warehouse mezzanine, light crane |
| 12–18 | 900–1,400 | 12–15 | Industrial bay, pipe bridge |
| 18–25 | 1,400–2,000 | 12–14 | Heavy crane runway, conveyor support |
| 25–35 | 2,000–2,800 | 10–14 | Long pipe bridge, plant transfer line |
| 30–50+ | 2,500–4,000+ | 8–12 | Bridge approach spans (with haunch) |
Final depth from analysis — ratios are preliminary only. Bridge projects may use haunched girders outside these bands.
Material Selection
Answer: Plate girder material is selected from IS 2062 grades based on stress demand, weldability, temperature and availability of plate thickness from Indian mills.
IS 2062 Steel Grades for Plate Girders
Answer: IS 2062 E350 is the default for heavy plate girders in industrial and bridge work; E250 suits moderate spans; E450 applies to high-stress or seismic-critical members.
IS 2062 Steel Grade Comparison for Plate Girders
| Grade | Yield (MPa) | Typical Plate Girder Use | Design Note |
|---|---|---|---|
| E250 (Fe410) | 250 | Light industrial spans, secondary girders | Economical; thicker sections |
| E350 (Fe490) | 350 | Crane girders, bridge girders, pipe bridges | Most common for heavy plate girders |
| E450 (Fe570) | 450 | High-stress bridge or seismic girders | Stricter welding and NDT |
See IS 2062 Steel Grades Guide for full chemical and mechanical data.
Plate Girder Design as per IS 800:2007
Answer: IS 800 plate girder design uses limit state method — factored loads from IS 875 combinations applied to check member resistance in bending (Section 8), shear (Section 6.7), combined interaction, connections (Section 10) and deflection (Section 5).
Key IS 800 clauses for plate girders:
- Section 6.7 — Webs without or with stiffeners; shear buckling design
- Section 8.2 — Lateral-torsional buckling of girders with unrestrained compression flange
- Section 8.4 — Bending and shear interaction
- Section 8.6 — Bearing stiffener and load-bearing stiffener design
- Section 10 — Welded and bolted connection design at supports and splices
Bridge projects may additionally reference IRC:24 for composite or non-composite bridge superstructures while retaining IS 800 steel design principles. Read our IS 800 Guide for code navigation.
Fabrication Process
Answer: After design approval, plate girders move through cutting, fit-up, welding, NDT, camber verification and coating in the workshop — a execution phase distinct from design but constrained by design details.
- CNC cutting of web and flange plates from approved nest drawings
- Fit-up in jig with root gap control for web-to-flange welds
- Submerged arc welding (SAW) on long flange welds; SMAW/FCAW for stiffeners
- Stiffener welding per shop drawing — full contact with bearing stiffeners at supports
- UT on full-penetration butt welds and critical fillet categories
- Camber check against design offset before blast and paint
- Marking, dispatch in modules sized for road transport
Design engineers should specify weld access, stiffener cope details and splice locations compatible with transport limits. Detailed workshop scope is on the plate girder fabrication product page — this design guide does not duplicate that commercial specification.
Quality Control and Inspection
Answer: Plate girder QC verifies material identity, weld integrity, dimensional accuracy (including camber and sweep), stiffener placement and coating — against project ITP and IS 800 fabrication tolerances.
Inspection Requirements Table
| Inspection | Scope | Method |
|---|---|---|
| Material receipt | Grade, thickness, MTC | Document review; PMI if specified |
| Fit-up | Gap, alignment, stiffener contact | Visual + dimensional |
| Welding | WPS compliance | Visual; weld map traceability |
| UT | Full-penetration web-flange welds | IS 1608; 100% on critical joints |
| RT | Specified bridge or licensor joints | NABL third-party |
| Dimensional | Depth, camber, sweep, length | Survey vs shop drawing |
| Coating | DFT, blast profile | Gauge logs per system |
Quality Control Table
| QC Stage | Acceptance Basis | Record |
|---|---|---|
| Cutting release | Approved shop drawing revision | Cutting plan sign-off |
| Weld completion | IS 816 / WPS | Welder ID + weld map |
| NDT clearance | ITP joint category | UT/RT report |
| Final release | Dimensional + coating | Dispatch inspection report |
Applications of Plate Girders
Answer: Plate girders serve any structure requiring long-span flexural steel where rolled sections are insufficient — across infrastructure and heavy industry.
- Plate girder bridge and ROB/Flyover approaches
- EOT and gantry crane runway girders in factories and steel plants
- Long-span warehouse steel girders and logistics hubs
- Pipe bridge and pipe rack main girders in refineries
- Conveyor gallery long spans in cement and mining plants
- Transfer line and equipment support industrial building girders
Industrial facilities frequently combine plate girders with pipe rack structures for equipment support, utility routing and process plant infrastructure.
Advantages of Plate Girders
Answer: Custom depth, optimised weight, long span capability and camber control make plate girders the standard solution for heavy flexural steel in India.
- Any span-depth ratio within transport and erection limits
- Flange and web thickness matched to actual stress envelope
- Compatible with composite concrete deck (bridges) or crane rail systems (industrial)
- Shop-controlled welding quality on critical flange-web joints
- Modular splicing for oversize dispatch
Limitations of Plate Girders
Answer: Plate girders cost more per metre than rolled beams in fabrication labour, require skilled welding and NDT, and need careful stiffener detailing to avoid buckling failures.
- Higher fabrication time than rolled section placement
- Welding distortion requires camber and straightening control
- Transport width/height limits on deep girders
- Site splice alignment critical on long bridge spans
- Not economical for short light spans where rolled beams suffice
Common Design Mistakes
Answer: Frequent errors include unstiffened slender webs, wrong IS 875 load category, ignored LTB restraint, and splice locations that conflict with transport.
- Omitting bearing stiffeners under crane wheel loads
- Using E250 where E350 would reduce weight and deflection
- Ignoring wind uplift on roof-level crane girders in open sheds
- Intermediate stiffener spacing exceeding IS 800 limits
- Connection design not matching fabrication split line
- Copying rolled beam details onto plate girder without stiffener review
Comparison Tables
Plate Girder vs Rolled Beam
| Criteria | Plate Girder | Rolled Beam (ISMB/ISWB) |
|---|---|---|
| Span range | 12 m – 50 m+ | Typically ≤ 12 m economical |
| Depth | Custom | Fixed catalog depth |
| Fabrication | Shop welded plates | Ready section; cut and drill |
| Stiffeners | Designed per IS 800 | Usually not required |
| Cost driver | Welding + NDT labour | Material weight + handling |
| Best for | Bridges, cranes, long industrial spans | Buildings, short platforms |
Plate Girder vs Built-Up Beam
| Criteria | Plate Girder | Built-Up Beam (general) |
|---|---|---|
| Definition | Plate web + flange I/box; stiffener design central | Any welded built section (channels, plates) |
| Depth | Often 1,000 mm+ | Variable; includes light PEB rafters |
| Design complexity | Web shear + stiffener rules | May use simpler rolled-equivalent checks |
| Typical use | Bridges, cranes, pipe bridges | PEB rafters, mezzanine, columns |
Built-up beams are commonly used where standard rolled sections cannot satisfy span, loading or fabrication requirements. View our Built-Up Beam Fabrication capability for project-specific manufacturing and delivery requirements.
Welded Plate Girder vs Bolted Girder
| Criteria | Welded Plate Girder | Bolted Built-Up Girder |
|---|---|---|
| Shop assembly | Web-flange SAW welds | High-strength bolted flange-web angles |
| Indian practice | Standard for heavy girders | Rare for main girders; used in splices |
| NDT scope | UT on coded welds | Bolt tension verification |
| Site work | Bolted field splices between modules | More field bolting |
Bridge Plate Girder vs Industrial Plate Girder
| Criteria | Bridge Plate Girder | Industrial Plate Girder |
|---|---|---|
| Code context | IS 800 + IRC:24 often | IS 800 + IS 807 for cranes |
| Loading | IRC vehicle, impact, crowd | Crane wheel, DL, maintenance LL |
| Detail | Haunched flanges, shear studs | Rail clips, stiffeners at wheels |
| NDT | Higher RT/UT percentage | UT on full-pen welds typical |
| Deflection | Strict IRC serviceability | IS 807 / span/600 for cranes |
Applicable Standards Table
| Standard | Application to Plate Girders |
|---|---|
| IS 800:2007 | Member design, connections, fabrication tolerances |
| IS 875 | Dead, live, wind loads on girders and decks |
| IS 2062 | Plate and flange material grades |
| IS 816 / IS 9595 | Welding procedure and quality |
| IS 807 | Crane loads on industrial crane girders |
| IRC:24 | Road bridge steel superstructures (where specified) |
| IS 1893 | Seismic load combinations with girders in frames |
Cost Factors Table (Design-Driven)
| Design Decision | Impact on Fabrication Cost |
|---|---|
| Deeper girder (lower stress) | More web area but thinner plates — net effect varies |
| More stiffeners | + labour and weld length |
| E350 vs E250 | Material premium ~8–15%; often less total weight |
| 100% UT on web-flange welds | + ₹12–25/kg on girder weight |
| Multi-piece field splice vs single span | Splice detail cost vs transport saving |
| Bridge-grade NDT (RT) | Significant third-party testing cost |
Industry Applications
Answer: Plate girders appear wherever long-span flexural steel is specified in Indian industrial and infrastructure EPC contracts.
- Bridge structures — ROB, flyover, pedestrian FOB main girders
- Warehouses & logistics parks — long clear-span roof girders
- Manufacturing plants — crane runway systems
- Refineries & petrochemical — pipe bridge and rack girders (refinery steel structures)
- Steel & cement plants — conveyor gallery spans (cement plant structures)
- Power plants — turbine hall and coal handling steel
- Data centers — long-span roof girders for equipment halls
- Infrastructure — metro and airport ancillary structures
Manufacturing Capability
Suncorporation Fabricators & Engineers fabricates industrial plate girder and bridge packages from approved shop drawings at Jeedimetla, Hyderabad — 500+ MT monthly workshop capacity, SAW welding, CNC cutting, in-house UT/MPI and pan-India dispatch. Design remains with the project structural engineer; we execute structural steel fabrication to drawing with full EPC documentation.
Quality Assurance Process
QA follows project ITP: material MTC verification → cutting release → weld map traceability → NDT per joint category → camber and dimensional sign-off → coating DFT → dispatch release. Non-conforming girders are held until rework or documented concession.
Material Traceability
IS 2062 plate is logged by heat number against MTC before cutting. Stiffener and flange plate identities are traceable on dispatch records for EPC material control registers — supporting IS 2062 steel grades verification at site receipt.
Inspection and Testing
Full-penetration flange-web welds receive UT per project spec; bridge and critical industrial packages may add RT through NABL labs. Dimensional reports include camber, sweep and depth at quarter points along the girder length.
Project Experience
Plate girder and heavy girder fabrication on metro, airport, industrial crane and process plant programmes — executed from consultant-approved drawings with indexed weld and NDT dossiers for PMC review.
Industries Served
EPC contractors, bridge engineers, industrial developers and plant owners across infrastructure, refining, cement, steel, power and logistics — supplied as defined-scope fabrication and erection, not structural design services.
People Also Ask
Plate girders carry bending and shear over long spans in bridges, crane runways, pipe bridges, warehouse roofs and conveyor galleries where rolled steel beams are too shallow or unavailable.
Apply IS 875 loads, analyse for M and V, size web and flanges per IS 800:2007, classify the section, design stiffeners, check deflection and detail connections before issuing shop drawings.
An I-beam is a rolled section with fixed dimensions; a plate girder is built from welded plates with custom depth and plate thicknesses for specific span and load requirements.
IS 800:2007 is the primary design code; loads come from IS 875; material from IS 2062; crane loads from IS 807 where applicable.
IS 2062 E350 is most common for heavy plate girders; E250 for lighter spans; E450 for high-stress applications.
Stiffeners prevent web buckling, transfer bearing reactions at supports and provide restraint to the compression flange against local instability.
Related Technical Guides
Frequently Asked Questions
What is a plate girder?
A plate girder is a built-up steel beam with a web plate and top and bottom flange plates welded together, designed to carry bending and shear over spans beyond standard rolled beam capacity — common in bridges, crane runways and industrial long spans.
What is the difference between a plate girder and a rolled beam?
A rolled beam (ISMB/ISWB) is a mill-produced section with fixed dimensions. A plate girder is custom-fabricated from plates with designed depth, flange size and stiffeners — used when rolled sections cannot meet span, load or deflection requirements.
What steel grade is used for plate girders?
IS 2062 E350 is standard for heavy plate girders in India. E250 applies to lighter industrial girders; E450 for high-stress or seismic-critical members. Grade selection follows IS 800 stress and ductility requirements.
How are plate girders fabricated?
Plates are CNC-cut, fitted in jigs and welded (typically SAW on flange-web joints), with stiffeners added per shop drawings. NDT, camber check, blasting and painting precede dispatch. Field splices bolt modules at site.
What is the maximum span of a plate girder?
Industrial plate girders commonly span 12–35 m; bridge steel girders exceed 40–50 m with haunched or spliced multi-span systems. Maximum span is governed by depth, weight, transport and deflection — not a fixed code limit.
What standards govern plate girder design?
IS 800:2007 governs design; IS 875 for loads; IS 2062 for material; IS 816 for welding. Bridges may add IRC:24; crane girders add IS 807.
What is a welded plate girder?
A welded plate girder has web-to-flange joints completed by submerged arc or fillet welding in the workshop — the standard form of plate girder construction in India, as opposed to bolted flange-web assemblies.
What are bearing stiffeners?
Bearing stiffeners are full-depth plates welded to the web at supports and under concentrated loads (e.g. crane wheels) to transfer reactions and prevent web crippling and local buckling per IS 800.
What are intermediate stiffeners?
Intermediate stiffeners are vertical plates between supports that subdivide the web panel, increasing shear buckling resistance and providing flange restraint when required by IS 800 web slenderness limits.
How is plate girder quality inspected?
Through MTC verification, visual and dimensional inspection, UT/RT on coded welds per ITP, camber measurement and coating DFT logs — with third-party witness at EPC hold points when specified.
What is plate girder design per IS 800?
IS 800 plate girder design checks section classification, bending capacity, shear capacity, combined M-V interaction, LTB, stiffener requirements and deflection under factored IS 875 load combinations.
When should a plate girder be used instead of a truss?
When a solid web beam is simpler to maintain, deflection paths are straightforward and span is moderate. Very long spans or heavy roof loads may favour a steel truss — see our steel truss guide.
Do plate girders need camber?
Yes, when dead load deflection must be offset — camber is set in the fabrication shop per design value and verified before dispatch. Crane girders and bridge girders commonly specify camber.
How do IS 875 loads affect plate girder design?
IS 875 dead, live and wind loads determine the moment and shear envelopes that size web and flange plates. Higher loads require deeper or thicker sections — see the IS 875 guide.
Who designs plate girders on an EPC project?
The structural engineering consultant or EPC structural discipline designs girders per IS 800. The fabricator executes approved shop drawings — Suncorporation provides fabrication and erection, not primary structural design services.
Need Plate Girder Fabrication for Your Project?
Share approved plate girder shop drawings, GA schedules or enquiry BOQs for scope confirmation, capacity alignment and a technical fabrication proposal from Suncorporation Fabricators & Engineers. We fabricate welded plate girders, bridge girders and industrial crane girders from our Hyderabad workshop with IS 800-compliant QA documentation — design services remain with your project structural engineer.
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