Investigation Into Aspects of Falsework

HSE Health & Safety Executive Investigation into aspects of falsework Prepared by the School of Civil Engineering The University of Birmingham for the Health and Safety Executive CONTRACT RESEARCH REPORT 394/2001 © Crown copyright 2001 Applications for reproduction should be made in writing to: Copyright Unit, Her Majesty’s Stationery Office, St Clements House, 2-16 Colegate, Norwich NR3 1BQ First published 2001 ISBN 0 7176 2232 0 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording or otherwise) without the prior written permission of the copyright owner. HSE Health & Safety Executive Investigation into aspects of falsework Eur Ing P F Pallett, Dr M P N Burrow, Professor L A Clark and Mr R T Ward School of Civil Engineering The University of Birmingham Edgbaston Birmingham West Midlands B15 2TT United Kingdom The results are presented of an investigation into the verticality of falsework achieved on construction sites and of the views of practitioners on how stability of falsework is demonstrated in the design process and achieved on site. Verticality data were measured at eleven construction sites. Based on the verticality of their entire height, the numbers of falsework legs on each site visit which were found not to be within tolerance varied from 0% to 50%, when compared against the current British criteria, and from 0% to 33%, when using the proposed European criteria. The difference occurs because the British criteria are more stringent. Two of the eleven sites were rated as inadequate in terms of the achievement of falsework verticality when using the British criteria, but no site was rated as inadequate according to the European criteria. The general performance does not appear to have improved since a similar study was conducted in 1989. There is a lack of understanding of the principles of stability amongst practitioners, and the contracting sector does not appreciate the implications of the assumptions made by the suppliers when designing a falsework system. This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE policy. HSE BOOKS FOREWORD The current basic philosophy of the use and operation of the temporary works used to support insitu concrete, precast units and steelwork, better known as "falsework", was established following a major collapse in 1972 of a falsework structure on the River Loddon, near Reading. In this incident three operatives were killed. The subsequent HMSO Report, better known as the Bragg Report, published in 1975, set requirements for erection and stability of these temporary structures. The recommendations were substantially incorporated into the British Standard Code of Practice in 1982. The Code has undergone only one minor amendment since, and remains the authoritative guidance document on the subject. Since the first publication of the Code the industry has changed in the intervening years, with greater use of specialist contractors, altered methods of design and procurement of falsework and changes to the type and method of operation of the equipment used. Furthermore, a forthcoming European Standard on temporary works, which will supersede in part the current British Code of Practice, specifies new requirements for the stability of falsework. To enable appropriate codes and regulations to be formulated in the future, this research project was commissioned to identify the changes in practice which have occurred within the industry, to establish and verify the erection tolerances achieved on site and to collate manufacturers' recommendations on the provision of stability. ii CONTENTS FOREWORD.............................................................................................................................................II CONTENTS............................................................................................................................................. III SUMMARY................................................................................................................................................V 1 INTRODUCTION ..............................................................................................................................1 1.1 HISTORY........................................................................................................................................1 1.2 AIMS AND OBJECTIVES...................................................................................................................3 1.3 REPORT OUTLINE ..........................................................................................................................4 2 STANDARDS......................................................................................................................................5 2.1 INTRODUCTION..............................................................................................................................5 2.2 BRITISH STANDARD - BS 5975, CODE OF PRACTICE FOR FALSEWORK...........................................5 2.3 BRITISH STANDARD-BS EN 1065, ADJUSTABLE TELESCOPIC STEEL PROPS.................................6 2.4 AUSTRALIAN STANDARD-AS 3610, FORMWORK FOR CONCRETE ..................................................8 2.5 GERMAN STANDARD-DIN 4421, FALSEWORK - CALCULATION, DESIGN AND CONSTRUCTION .10 2.6 AMERICAN STANDARD - ACI 347R, GUIDE TO FORMWORK FOR CONCRETE ..............................10 2.7 CONCLUSIONS..............................................................................................................................12 3 FUTURE EUROPEAN PERFORMANCE STANDARD prEN 12812....................................15 3.1 INTRODUCTION............................................................................................................................15 3.2 DESIGN OF FALSEWORK ..............................................................................................................15 3.3 CLASSIFICATION..........................................................................................................................16 3.4 ECCENTRICITIES OF LOAD ...........................................................................................................16 3.5 ANGULAR CHANGES AND ECCENTRICITIES AT SPIGOT JOINTS ......................................................16 3.6 INITIAL BOW IMPERFECTIONS ....................................................................................................18 3.7 INITIAL SWAY IMPERFECTIONS ....................................................................................................18 3.8 LATERAL STABILITY REQUIREMENTS ..........................................................................................18 4 THEORY OF VERTICALITY AND STABILITY...................................................................21 4.1 VERTICALITY OF FALSEWORK....................................................................................................21 4.2 VERTICALITY - EFFECT OF SPIGOTS/JOINTS................................................................................22 4.3 OVERALL STABILITY ..................................................................................................................23 4.4 STABILITY FORCE.......................................................................................................................23 5 PREVIOUS RESEARCH ...............................................................................................................25 5.1 INTRODUCTION............................................................................................................................25 5.2 TEXTS..........................................................................................................................................25 5.3 SCAFFOLDING, SHORING AND FORMING INSTITUTE.................................................................25 5.4 OSHA REGULATIONS .................................................................................................................25 5.5 RESEARCH MATERIAL ................................................................................................................26 6 ANGULAR CHANGES AND ECCENTRICITIES AT SPIGOT JOINTS ..........................27 6.1 INTRODUCTION............................................................................................................................27 6.2 METHODOLOGY...........................................................................................................................27 6.3 COMMONLY USED PROPRIETARY SYSTEMS ................................................................................28 6.4 SUMMARY ...................................................................................................................................34 7 TOLERANCES ON VERTICALITY - SITE SURVEYS..........................................................35 7.1 INTRODUCTION............................................................................................................................35 7.2 METHODOLOGY...........................................................................................................................35 7.3 VERTICALITY RESULTS ...............................................................................................................49

Load more