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IS 806 : 1968Code of Practice for Use of Steel Tubes in General Building Construction

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ANSI/AISC 360 · EN 1993-1-1 · CIDECT Design Guide 1 (3rd Edition)
CurrentSpecializedCode of PracticeBIMStructural Engineering · Structural Design and Loading
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OverviewValues6InternationalTablesFAQ4Related

IS 806:1968 is the Indian Standard (BIS) for use of steel tubes in general building construction. This code covers the structural design, fabrication, and erection of steel tubes used in general building construction. It provides guidelines on permissible stresses, member design (tension, compression, flexure), and joint detailing (especially welded and flattened connections) for lightweight tubular structures like roof trusses and industrial sheds.

Provides guidelines for the use of steel tubes in general building construction.

Overview

Status
Current
Usage level
Specialized
Domain
Structural Engineering — Structural Design and Loading
Type
Code of Practice
International equivalents
ANSI/AISC 360-22 · AISC (American Institute of Steel Construction), USAEN 1993-1-1:2005 · CEN (European Committee for Standardization), EuropeCIDECT Design Guide 1 (3rd Edition) · CIDECT (International Committee for the Development and Study of Tubular Construction), International
Typically used with
IS 1161IS 800IS 816IS 1363
Also on InfraLens for IS 806
6Key values2Tables4FAQs

BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.

Practical Notes
! Ends of steel tubes must be fully sealed (by welding plates, crimping, or plugging) to prevent internal corrosion, especially in exposed environments.
! When flattening tube ends for bolted connections, ensure the transition is smooth and not steeper than 1 in 6 to avoid high stress concentrations.
! Welded joints are highly preferred for tubular trusses to maximize structural efficiency and avoid local crushing of the tube wall from bolted connections.
Frequently referenced clauses
Cl. 4MaterialsCl. 5Permissible StressesCl. 6Design of MembersCl. 7Joints and ConnectionsCl. 8Fabrication and Erection
Pulled from IS 806:1968. Browse the full clause & table index below in Tables & Referenced Sections.
steel tubesstructural steeltubular sectionshollow sections

International Equivalents

Similar International Standards
ANSI/AISC 360-22AISC (American Institute of Steel Construction), USA
MediumCurrent
Specification for Structural Steel Buildings
Covers design of all steel building structures, including Hollow Structural Sections (HSS), but is primarily based on Limit State Design (LSD).
EN 1993-1-1:2005CEN (European Committee for Standardization), Europe
MediumCurrent
Eurocode 3: Design of steel structures - Part 1-1: General rules and rules for buildings
The primary European standard for steel building design, including circular and rectangular hollow sections, based on Limit State Design.
BS 5950-1:2000BSI (British Standards Institution), UK
MediumWithdrawn
Structural use of steelwork in building - Part 1: Code of practice for design - Rolled and welded sections
Predecessor to Eurocode 3 in the UK; covered tubular structures and transitioned from Allowable Stress to Limit State design in later versions.
CIDECT Design Guide 1 (3rd Edition)CIDECT (International Committee for the Development and Study of Tubular Construction), International
LowCurrent
Design guide for circular hollow section (CHS) joints under predominantly static loading
A specialized, non-mandatory guide focusing specifically on the design of joints in tubular structures, which is a weakness of IS 806.
Key Differences
≠IS 806:1968 is based on the Allowable Stress Design (WSD) philosophy, which uses a single factor of safety on material stresses. Modern international standards like Eurocode 3 and AISC 360 are based on Limit State Design (LSD), using partial safety factors for loads and material resistances.
≠IS 806 uses a single, simplified formula for determining the allowable compressive stress for columns. Eurocode 3 uses a system of multiple buckling curves (a, b, c, d, a0) that account for section shape, manufacturing process (hot-finished vs. cold-formed), and residual stresses.
≠The guidance on connection design in IS 806 is very basic and general. Modern codes and specialized guides (like CIDECT) provide extensive, empirically validated formulas for various joint types (K, N, Y, KT) and failure modes (e.g., chord plastification, punching shear).
≠IS 806 references outdated steel material specifications (e.g., St 32, St 42 from IS 1161:1963). Current international standards specify modern, high-strength steels with much stricter quality control and a wider range of available grades (e.g., S355, S420 in Europe; Gr. B, Gr. C in ASTM A500).
≠Modern codes like Eurocode 3 classify sections (Class 1-4) based on their susceptibility to local buckling, which determines their suitability for plastic design. IS 806 does not use such a classification system and implicitly prevents plastic design by its stress limits.
Key Similarities
≈Both IS 806 and modern standards are founded on the same fundamental principles of structural mechanics, such as equilibrium of forces and moments.
≈The concept of using an 'effective length' (kL) for compression members to account for end-restraint conditions is a fundamental principle shared between IS 806 and all major international codes, although the specific k-factors may differ.
≈The general scope is similar: providing rules for the safe design of steel tubular members (columns, beams, trusses) in building structures against various actions like dead, live, and wind loads.
≈Both IS 806 and modern standards like AISC 360 (in its ASD portion) specify the permissible axial tensile stress on the gross section as a similar fraction of the steel's yield strength (0.6 * fy).
Parameter Comparison
ParameterIS ValueInternationalSource
Design PhilosophyAllowable Stress Design (WSD)Limit State Design (LSD) / Load and Resistance Factor Design (LRFD)EN 1993-1-1 / AISC 360-22
Permissible Axial Tensile Stress (Gross Section)0.6 * f_y0.6 * F_y (in ASD method)ANSI/AISC 360-22
Permissible Bending Stress (Compact Members)~0.52 * f_y (derived from specified stress of 12.6 kg/mm² for St 42 grade)0.66 * F_y (in ASD method)ANSI/AISC 360-22
Permissible Shear Stress (Average)0.4 * f_y0.6 * F_y (for HSS, in ASD method)ANSI/AISC 360-22
Modulus of Elasticity for Steel (E)2,047,000 kg/cm² (approx. 201,000 MPa)200,000 MPa (29,000 ksi)EN 1993-1-1 / AISC 360-22
Maximum Slenderness Ratio (l/r) for a main compression member180200 (Recommended limit)ANSI/AISC 360-22
Partial Safety Factor for Material (Stability)Not applicable (Factor of Safety is implicit in allowable stress)γ_M1 = 1.0EN 1993-1-1
⚠ Verify details from original standards before use

Key Values6

Quick Reference Values
Max slenderness ratio for compression members180
Max slenderness ratio for pure tension members400
Max slenderness ratio for tension members with reversal of stress from wind/earthquake350
Minimum thickness of tubes (accessible for painting/sealed)2.0 mm
Minimum thickness of tubes (exposed to weather, unsealed)2.5 mm
Maximum deflection for flexural membersSpan / 325
Key Formulas
P = pc * A (Axial compression capacity, where pc is permissible compressive stress and A is cross-sectional area)

Tables & Referenced Sections

Key Tables
Table 1 - Maximum Permissible Stresses in Welds
Table 2 - Effective Length of Struts
Key Clauses
Clause 4 - Materials
Clause 5 - Permissible Stresses
Clause 6 - Design of Members
Clause 7 - Joints and Connections
Clause 8 - Fabrication and Erection

Related Resources on InfraLens

Cross-Referenced Codes
IS 1161:2014Steel Tubes for Structural Purposes - Specifi...
→
IS 800:2007General Construction in Steel - Code of Pract...
→
IS 816:1969Code of Practice for Use of Metal Arc Welding...
→
IS 1363:2002Hexagon Head Bolts, Screws and Nuts of Produc...
→

Frequently Asked Questions4

What code specifies the material properties for the structural tubes?+
IS 1161 (Steel Tubes for Structural Purposes) specifies grades like YSt 210, YSt 240, and YSt 310 which are designed using IS 806.
Do structural steel tubes need to be sealed at the ends?+
Yes, to prevent internal rusting and moisture ingress, all open ends of tubes must be effectively sealed or welded closed.
What is the maximum slenderness ratio for a tubular strut?+
The maximum slenderness ratio for tubular members carrying dead and imposed compressive loads is 180.
Can tubular structures be bolted?+
Yes, but the tube ends typically need to be flattened or fitted with welded gusset plates to facilitate bolting without crushing the hollow section during tightening.

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