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© The British Standards Institution 2022

Published by BSI Standards Limited 2022

ISBN 978 0 539 22780 2

ICS 91.220

The following BSI references relate to the work on this document:
Committee reference B/514/24
Draft for comment 21/30412754 DC

Foreword

Publishing information

This part of BS 1139 is published by BSI Standards Limited, under licence from The British Standards Institution, and came into effect on 31 January 2022. It was prepared by Subcommittee B/514/24, Access towers, under the authority of Technical Committee B/514, Access and support equipment. A list of organizations represented on this committee can be obtained on request to the committee manager.

Supersession

This part of BS 1139 supersedes BS 1139‑6:2014, which is withdrawn.

Relationship with other publications

BS 1139, Metal scaffolding, was published in six parts:

Part 1.1: Tubes - Specification for steel tube (superseded by BS EN 39:2001);
Part 1.2: Tubes - Specification for aluminium tube;
Part 2.1: Couplers - Specification for steel couplers, loose spigots and base-plates for use in working scaffolds and falsework made of steel tubes (superseded by BS EN 74-1:2005);
Part 3: Specification for prefabricated mobile access and working towers (superseded by BS EN 1004‑1:2020);
Part 4: Specification for prefabricated steel splitheads and trestles;
Part 5: Specification for materials, dimensions, design loads and safety requirements for service and working scaffolds made of prefabricated elements (superseded by BS EN 12810-1:2003);
Part 6: Specification for prefabricated tower scaffolds outside the scope of BS EN 1004, but utilizing components from such systems.

This part of BS 1139 should be read in conjunction with, and is complementary to, BS EN 1004‑1, Mobile access and working towers made of prefabricated elements — Materials, dimensions, design loads, safety and performance requirements.

Information about this document

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1 Scope

This part of BS 1139 specifies requirements for the structural design of prefabricated tower scaffolds utilizing components from mobile access and working towers specified in BS EN 1004‑1 but in configurations that are outside of the scope of that standard.

These configurations include:

high level tower scaffolds outside the maximum height limits of BS EN 1004‑1;
tower scaffolds with more than one working platform at one time;
large deck tower scaffolds;
linked tower scaffolds;
cantilever tower scaffolds;
stepped tower scaffolds;
tower scaffolds used as a means of access to another place;
non-mobile towers built on base plates instead of castors; and
tower scaffolds subject to wind loads greater than 0.1 kN/m².

NOTE Towers with wind loads up to 0.1 kN/m² are specified in BS EN 1004‑1. Where a prefabricated tower scaffold might be subject to wind in excess of 0.1 kN/m², and it cannot be dismantled or moved to avoid these winds, suitable wind design criteria can be found in this British Standard.

This British Standard does not cover prefabricated tower scaffolds using guys as a method of stabilization.

This British Standard does not cover prefabricated towers intended to be lifted.

2 Normative references

3 Terms and definitions and symbols

3.1 Terms and definitions

3.2 Symbols

4 Classification

4.1 Load classes

4.2 Access classes

4.3 Height classes

4.4 Configuration classes

4.5 Wind classes

5 Materials

6 General requirements

6.1 General and standard configurations

6.2 Dimensions

6.3 Openings within platforms

6.4 Side protection

6.5 Castor wheels and base plates

6.6 Access to platforms

6.7 Means for stabilizing

6.8 Connections

6.9 Working and access platform units

6.10 Assembly and dismantling

6.11 Requirements for prefabricated tower scaffolds less than 2 m working platform height

6.12 Requirements for prefabricated tower scaffolds used for access to another place

6.13 Vertical distances between platforms

7 Requirements for structural design

7.1 General

7.2 Characteristic actions on the complete structure including its parts

7.3 Characteristic actions on parts of the structure

7.4 Deflections

8 Structural design

8.1 Basic design principle

8.2 Structural analysis

8.3 Verification

8.4 Positional stability

9 Deflection

10 Design validation

10.1 Method

10.2 Verification report

10.3 Design certificate

11 Information to be supplied with the prefabricated tower scaffold

11.1 General

11.2 Identification of components in the structure

11.3 Assembly, permissible alterations and dismantling

11.4 Stability

11.5 Application and moving

11.6 Inspection, care and maintenance

12 Marking

13 Assessment

Bibliography

BS 1139-6:2022

Metal scaffolding - Prefabricated tower scaffolds outside the scope of BS EN 1004-1, but utilizing components from such systems. Specification

Current

Published:

31 Jul 2022