General Construction in Steel —
Code of Practice
The primary Indian Standard for the design of steel structures using the Limit State Method. Covers industrial buildings, multi-storey frames, trusses, and all structural steelwork except cold-formed sections and bridges.
📋 Amendments Applied: This summary incorporates the 2008 corrigendum and 2012 amendment. Always verify against the latest BIS amendment sheet before design.
IS 800:2007 applies to the design, fabrication, and erection of steel structures used in buildings and general civil engineering works. It is based entirely on the Limit State Method (LSM), replacing the earlier Working Stress Method of IS 800:1984.
The code does not cover:
- › Cold-formed steel sections (see IS 801)
- › Steel bridges (see IRC 24)
- › Crane girders and overhead travelling cranes (separate provisions)
- › Structures subject to fatigue loading (Cl. 13 applies separately)
Key Change from 1984 Edition The 2007 revision completely replaced the Working Stress Method with the Limit State Method, aligning Indian practice with Eurocode 3 and international standards. The WSM approach is no longer permitted for new designs under this code.
Structural steel conforming to IS 2062 is the primary material. The grade designation uses the prefix 'E' followed by the minimum yield strength in MPa.
| Grade (IS 2062) | fy (MPa) ≤ 20 mm | fy (MPa) 20–40 mm | fu (MPa) | Typical Use |
|---|---|---|---|---|
| E 250 (Fe 410) | 250 | 240 | 410 | General structural use, angles, channels |
| E 300 | 300 | 290 | 440 | Plate girders, heavy columns |
| E 350 | 350 | 330 | 490 | High-strength applications, bridges |
| E 410 | 410 | 390 | 540 | Special high-strength structures |
Modulus of Elasticity E = 2 × 10⁵ MPa (200 GPa) for all grades. Shear modulus G = 0.769 × 10⁵ MPa. Poisson's ratio ν = 0.3. Unit weight = 78.5 kN/m³ (Cl. 2.2.4).
IS 800:2007 adopts the Limit State Method, ensuring the structure satisfies both strength (collapse) and serviceability requirements throughout its design life.
| Load Combination | DL | LL | WL / EL | Reference |
|---|---|---|---|---|
| DL + LL | 1.5 | 1.5 | — | IS 875 Part 5 |
| DL + WL | 1.5 / 0.9 | — | 1.5 | IS 875 Part 5 |
| DL + LL + WL | 1.2 | 1.2 | 1.2 | IS 875 Part 5 |
| DL + EQ | 1.5 / 0.9 | — | 1.5 | IS 1893 |
| DL + LL + EQ | 1.2 | 1.2 | 1.2 | IS 1893 |
Load Combinations per IS 875 Part 5 Load combinations and partial safety factors for loads are taken from IS 875 (Part 5):1987. The 0.9 factor on DL applies when dead load counteracts the effect of other loads (e.g., overturning).
The design strength of a tension member is the minimum of three limit states: gross section yielding, net section fracture, and block shear failure.
Net Area Calculation For staggered bolt holes, the net area is calculated using the critical path method. Deduct the full hole diameter (bolt diameter + 2 mm clearance) from the gross area for each hole on the critical path (Cl. 6.3.1).
The design compressive strength is based on buckling curves (a, b, c, d) depending on the section type and axis of buckling. The slenderness ratio λ governs the design.
| End Condition | Effective Length (Le) | Clause |
|---|---|---|
| Both ends pinned | 1.0 L | Table 11 |
| Both ends fixed | 0.5 L | Table 11 |
| One end fixed, one pinned | 0.7 L | Table 11 |
| One end fixed, one free (cantilever) | 2.0 L | Table 11 |
| One end fixed, one end guided (rotation fixed) | 1.2 L | Table 11 |
| Member Type | Max. Slenderness Ratio (KL/r) |
|---|---|
| Members carrying compressive loads | 180 |
| Members carrying tension (reversal possible) | 250 |
| Tension members (no reversal) | 400 |
Buckling Curves IS 800 uses four buckling curves (a, b, c, d) with imperfection factors α = 0.21, 0.34, 0.49, 0.76 respectively. The applicable curve depends on the section type (I-section, hollow section, angle, etc.) and the axis of buckling (Table 10).
The design bending strength depends on whether the compression flange is laterally restrained. Unrestrained beams must be checked for Lateral Torsional Buckling (LTB).
| Section Class | Description | Design Basis |
|---|---|---|
| Plastic | Can form plastic hinge with rotation capacity | Zp (plastic modulus) |
| Compact | Full plastic moment, limited rotation | Zp |
| Semi-compact | Reaches yield stress at extreme fibre only | Ze (elastic modulus) |
| Slender | Local buckling before yield | Reduced effective section |
Web Buckling & Crippling Webs of plate girders must be checked for buckling under concentrated loads (Cl. 8.7.3) and crippling at supports (Cl. 8.7.4). Provide load-bearing stiffeners where the web capacity is exceeded.
IS 800:2007 covers both ordinary (snug-tight) bolts and high-strength friction grip (HSFG) bolts. Weld design covers fillet welds and butt welds.
| Bolt Grade | fub (MPa) | fyb (MPa) | Typical Use |
|---|---|---|---|
| 4.6 | 400 | 240 | General connections, secondary members |
| 8.8 | 800 | 640 | Primary connections, moment connections |
| 10.9 | 1000 | 900 | HSFG bolts, slip-critical connections |
| Weld Parameter | Value / Rule | Clause |
|---|---|---|
| Throat thickness (fillet) | tt = 0.7 × s (s = leg size) | Cl. 10.5.3 |
| Min. fillet weld size | 3 mm (for t ≤ 10 mm); 5 mm (t = 10–20 mm) | Table 22 |
| Max. fillet weld size | t − 1.5 mm (for t ≤ 6 mm: t) | Cl. 10.5.8.1 |
| Design strength of fillet weld | fwd = fu / (√3 × γmw); γmw = 1.25 | Cl. 10.5.7 |
Minimum Bolt Spacing Minimum pitch = 2.5d (bolt diameter). Minimum edge distance = 1.7d₀ (hole diameter) for sheared edges; 1.5d₀ for rolled/sawn edges. Maximum pitch = 16t or 200 mm (Cl. 10.2).
| Amendment | Year | Key Changes |
|---|---|---|
| Corrigendum No. 1 | 2008 | Corrections to Tables 10 and 11; typographical errors in buckling curve equations; clarification on effective length factors |
| Amendment No. 1 | 2012 | Revised provisions for fire resistance (Cl. 16); updated fatigue design clauses (Cl. 13); corrections to weld design formulas |
Revision in Progress A comprehensive revision of IS 800 is expected to further align with Eurocode 3 provisions, including updated imperfection factors, connection design, and seismic provisions for steel structures.