BS 5975:1996:2004 Edition
$227.44
Code of practice for falsework
| Published By | Publication Date | Number of Pages |
| BSI | 2004 | 150 |
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 1 | BRITISH STANDARD |
| 2 | Committees responsible for this British�Standard |
| 3 | Contents |
| 9 | Section 1 General 1.1 Scope 1.2 References 1.2.1 Normative references 1.2.2 Informative references 1.3 Definitions 1.3.1 baseplate 1.3.2 bay length 1.3.3 blinding 1.3.4 brace 1.3.5 camber 1.3.6 coupler 1.3.7 erection drawing 1.3.8 factor of safety |
| 10 | 1.3.9 falsework 1.3.10 floor centre 1.3.11 fork head 1.3.12 formwork and forms 1.3.13 foot tie 1.3.14 frame 1.3.15 grade stress 1.3.16 guard rail 1.3.17 joint pin 1.3.18 joist 1.3.19 lacing 1.3.20 permissible stress 1.3.21 permit to load 1.3.22 prop 1.3.23 repropping 1.3.24 scaffold 1.3.25 sole plate (or�sill) |
| 11 | 1.3.26 spigot pin 1.3.27 standard 1.3.28 stiff length (of�the�bearing) 1.3.29 strength class 1.3.30 strength ratio 1.3.31 strut 1.3.32 toe board 1.3.33 tower 1.3.34 wedge 1.4 Symbols |
| 14 | 1.5 Legislation |
| 15 | Section 2 Procedures 2.1 General 2.1.1 Introduction 2.1.2 Variety of falsework 2.1.3 Procedure when more than one organization is involved 2.2 Formality of procedures 2.2.1 It is important to establish responsibility for, and the scope of, the work of all those or… |
| 16 | 2.2.2 The main items for which responsibility should be established are: 2.3 Design brief 2.4 Communication of requirements |
| 17 | 2.5 Coordination and supervision 2.5.1 General 2.5.2 Falsework coordinator |
| 18 | 2.6 Checking 2.7 Alterations 2.8 Loading the falsework 2.9 Dismantling |
| 19 | Section 3 Materials and components 3.1 General considerations 3.1.1 Suitability of materials 3.1.2 Identification and properties 3.1.3 Handling of materials and components 3.2 Testing and inspection 3.2.1 Testing 3.2.2 Inspection 3.3 Steelwork (other than scaffold tube) 3.3.1 Quality of steel |
| 20 | 3.3.2 Identification of steel 3.3.3 Permissible stresses 3.3.4 Section properties 3.3.5 Fatigue 3.3.6 Welding and rectification of steelwork 3.4 Timber 3.4.1 Timber quality |
| 21 | Table 1 — Basic stresses and moduli of elasticity for the wet condition Table 2 — Equivalent strength classes for softwoods graded in accordance with BS�4978 |
| 22 | Table 3 — Equivalent strength classes for North American softwoods graded in accordance with NLGA and NGRDL… 3.4.2 Modification factors |
| 23 | Table 4 — Modification factor, Table 5 — Modification factor, Table 6 — Modification factor, |
| 24 | Table 7 — Maximum depth�to�breadth ratios Table 8 — Permissible bending stress parallel to the grain for beams of different depths for�general falsew… |
| 25 | Table 9 — Permissible stresses and moduli of elasticity for general falsework applications 3.4.3 Timber that is not stress graded Table 10 — Commercial grade timber suitable to produce mainly class SC3 timber 3.4.4 Grading reused timber |
| 26 | 3.5 Concrete and concrete components 3.5.1 Mix design 3.5.2 Blinding concrete 3.5.3 Spread footings 3.5.4 New structural members 3.5.5 Second�hand structural members |
| 27 | 3.5.6 Precast concrete 3.6 Brickwork and blockwork 3.6.1 Characteristic strength 3.6.2 Rate of building 3.6.3 Age of loading 3.6.4 Reinforced brickwork and blockwork 3.6.5 Salvaged bricks and blocks 3.7 Other materials 3.7.1 General 3.7.2 Permissible stresses |
| 28 | 3.7.3 Deterioration 3.8 Steel scaffold tubes, couplers and other fittings 3.8.1 Equipment in general use 3.8.2 Non�standard scaffold tubes 3.8.3 Loads on struts 3.8.4 Straightening of scaffold tubes |
| 29 | 3.8.5 Corrosion and deterioration of steel scaffold tube and fittings 3.8.6 Scaffold fittings 3.8.7 Deterioration of scaffold couplers and fittings 3.9 Manufactured components for falsework 3.9.1 Types of manufactured components 3.9.2 Design and testing of manufactured components |
| 30 | 3.9.3 Information from the supplier 3.9.4 Factors of safety 3.9.5 Framed tower components for vertical load bearing 3.9.6 Adjustable steel props |
| 31 | Table 11 — Adjustable steel prop heights Figure 1 — Safe working loads for props |
| 32 | 3.9.7 Floor centres 3.9.8 Bridging girders 3.9.9 Military trestling systems |
| 33 | Section 4 Loads applied to falsework 4.1 General 4.2 Weights of materials 4.3 Self�weights 4.4 Imposed loads 4.4.1 General |
| 34 | 4.4.2 Permanent works loading 4.4.3 Construction operations |
| 36 | Figure 2 — Controlled heaping of concrete 4.5 Environmental loads 4.5.1 Wind loading |
| 37 | Figure 3 — Basic wind speed, |
| 38 | Figure 4 — Ground surface conditions and height above ground factor for wind, |
| 39 | Table 12 — Values of wind speed factor, |
| 40 | Table 13 — Dynamic wind pressure, |
| 41 | Table 14 — Force coefficient, |
| 44 | Figure 5 — Wind forces on soffit: wind blowing parallel to secondary beams Figure 6 — Wind forces on soffit: wind blowing parallel to primary beams |
| 45 | Figure 7 — Wind forces on edge formwork |
| 46 | Figure 8 — Wind forces on combined beam and soffit formwork |
| 47 | Figure 9 — Wind loading: combined formwork and falsework |
| 48 | 4.5.2 Water |
| 49 | 4.5.3 Snow 4.5.4 Ice |
| 50 | 4.5.5 Earth pressure |
| 53 | Section 5 Foundations and ground conditions 5.1 General 5.1.1 Introduction 5.1.2 Slope and stability 5.1.3 Depth of foundations 5.2 Site investigation for falsework foundations |
| 54 | Table 16 — Presumed allowable bearing pressure under vertical static loading |
| 55 | 5.3 Testing of soils 5.4 Allowable bearing pressures 5.5 Modification factors applied to presumed bearing pressures 5.5.1 Modification factor for reliability of site information 5.5.2 Settlements of the foundations underneath the falsework |
| 56 | Table 17 — Field identification and description of soils |
| 57 | Table 17 — Field identification and description of soils |
| 58 | 5.5.3 Ground water levels Table 18 — Ground water level modification factor 5.6 Simple foundations on sands and gravels 5.7 Simple foundations on cohesive soils 5.8 Heavy vibrations |
| 59 | 5.9 Fill material 5.10 Piles 5.11 Protection of the foundation area |
| 61 | Section 6 Design of falsework 6.1 General concepts 6.1.1 Introduction 6.1.2 Direction of falsework design 6.1.3 Checking the design 6.2 Design brief and basic approach 6.2.1 Design brief |
| 62 | 6.2.2 Basic approach |
| 64 | 6.3 Forces applied to falsework 6.3.1 General |
| 65 | 6.3.2 Combinations of forces |
| 66 | Figure 10 — Typical force combinations |
| 67 | 6.4 Analysis of falsework structure 6.4.1 General 6.4.2 Behaviour of structure 6.4.3 Structural strength |
| 68 | 6.4.4 Lateral stability |
| 69 | Figure 11 — Typical examples of stability of node points |
| 70 | Figure 11 — Typical examples of stability of node points |
| 72 | Figure 12 — Lateral restraint provided by friction |
| 73 | Table 19 — Minimum value of coefficient of static friction,� 6.4.5 Overall stability |
| 74 | 6.5 Foundations to falsework 6.5.1 Purpose of foundations 6.5.2 Falsework supported on permanent works foundation 6.5.3 Falsework supported on permanent works above ground level |
| 75 | 6.5.4 Falsework supported on the ground 6.5.5 Falsework founded in watercourses |
| 76 | Figure 13 — Base detail on slopes |
| 77 | 6.6 Additional considerations affecting certain design solutions 6.6.1 Clear span falsework systems 6.6.2 Independent towers in groups 6.6.3 Falsework (or�centring) for arches |
| 78 | 6.6.4 Horizontal or raking falsework 6.6.5 Mobile falseworks 6.7 Design using scaffold tube and fittings 6.7.1 General |
| 79 | Figure 14 — Maximum deviation of load path |
| 80 | Figure 15 — Eccentricity of loading |
| 81 | 6.7.2 Effective lengths of scaffold tube struts |
| 82 | Figure 16 — Effective lengths in tube and coupler scaffolding |
| 83 | Section 7 Work on site 7.1 Introduction 7.2 Specific design instructions 7.3 General workmanship 7.3.1 Critical factors of workmanship 7.3.2 Accuracy of falsework |
| 84 | 7.3.3 Vertical movement |
| 85 | Figure 17 — Points of measurement of tolerances for purposely fabricated steelwork |
| 86 | 7.3.4 Top arrangements 7.3.5 Wedging 7.3.6 Lacing and bracing 7.3.7 Importance of details 7.4 Checking falsework 7.4.1 When to check |
| 87 | 7.4.2 Items to be checked |
| 88 | 7.5 Application of loads to falsework |
| 89 | 7.6 Dismantling 7.6.1 General 7.6.2 Supports required after general dismantling 7.7 Maintenance, inspection and identification of materials |
| 91 | Section 8 Standard solutions 8.1 Introduction 8.2 Procedure for the use of standard designs 8.3 Criteria assumed in preparing the standard solutions 8.3.1 Loadings 8.3.2 Factor of safety 8.3.3 Timber quality 8.3.4 Continuity 8.3.5 Plywood |
| 92 | 8.4 Limitations 8.4.1 Foundations 8.4.2 Support equipment |
| 93 | 8.4.3 Timber 8.4.4 Plywood 8.4.5 Construction 8.4.6 Stability |
| 94 | Figure 18 — Basic arrangement of bracing to provide stability |
| 95 | 8.4.7 Concrete placing 8.4.8 Tolerances 8.5 Dimensional information 8.5.1 Support of slabs 8.5.2 Support of individual beams |
| 96 | Figure 19 — Arrangement of members for construction of concrete slabs |
| 97 | Table 20 — Dimensions for standard solutions for slab support arrangements |
| 98 | Figure 20 — Arrangement of members for typical beam support |
| 99 | Table 21 — Dimensions for standard solutions for beam support arrangements |
| 101 | Annex A (informative) Permissible stresses and modulus of elasticity for steel grades generally used�in f… A.1 Permissible stresses |
| 102 | A.2 Young’s modulus |
| 103 | Table A.1 — Permissible axial compressive stress, |
| 104 | Annex B (informative) Properties of components in tube and coupler falsework B.1 Properties of steel scaffold tube complying with the requirements of BS�1139 Table B.1 — Section properties of steel scaffold |
| 105 | B.2 Axial compressive stress B.3 Safe working loads for scaffold fittings complying with the requirements of BS�1139 |
| 106 | Table B.2 — Maximum permissible axial stresses and loads in steel scaffold tubes manufactured�in accordance w… |
| 107 | Table B.3 — Maximum permissible axial stresses and loads in steel scaffold tubes manufactured�in accordance w… |
| 108 | Table B.4 — Safe working loads for individual couplers and fittings |
| 109 | Annex C (informative) Initial testing, quality control and inspection of falsework equipment C.1 Introduction C.2 Tests on falsework equipment C.3 Prototype and initial testing C.4 Quality control of manufacture |
| 110 | Annex D (informative) Fatigue in Bailey Bridge sections |
| 112 | Annex E (informative) Additional data on material properties E.1 Concrete shrinkage and creep E.2 Coefficient of linear expansion/contraction |
| 113 | E.3 Modulus of elasticity Table E.1 — Modulus of elasticity for concrete E.4 Density of reinforced concrete If the quality of steel by volume exceeds 2�%� and the aggregates are of normal density, the dens… Table E.2 — Density of reinforced concrete If the relative density of any of the aggregates exceeds�2.75, the density of the concrete should… The density of light�weight concretes should be determined from trial mixes. As a guide, the like… Table E.3 — Density ranges for light�weight concretes E.5 Masses and densities of materials E.6 Masses of corrugated steel sheeting E.7 Some unusual loads that frequently require consideration |
| 114 | Table E.4 — Masses of scaffolding materials Table E.5 — Masses and densities of men and materials Table E.6 — Masses of corrugated steel sheeting |
| 115 | Annex F (informative) Wave forces F.1 Definitions bore clapotis fetch still water depth� still water level wave height wave length F.2 Symbols F.3 General |
| 116 | F.4 Non-breaking waves |
| 117 | Figure F.1 — Non-breaking waves: section diagram Annex G (informative) Site investigations for foundations for falseworks G.1 Introduction G.2 General G.3 Preliminary appraisal |
| 118 | G.4 Depths for investigation and sampling G.5 Laboratory tests G.6 Final report and recommendations |
| 119 | Annex H (informative) Examples of design brief contents H.1 Design brief for a motorway bridge H.2 Design brief for a suspended floor in a building |
| 120 | Annex J (informative) Forces from concrete on sloping soffits J.1 General J.2 Forces associated with a level upper surface and a sloping base |
| 121 | Figure J.1 — Distribution of forces on sloping soffits J.3 Forces when the top and base of concrete are sloping, but there is no top formwork J.4 Forces when the top and base of the concrete are sloping and top formwork is in use J.5 Arches |
| 122 | Annex K (informative) Design of steel beams at points of reaction or concentrated load K.1 General K.2 Beams without bearing stiffeners |
| 124 | Table K.1 — Effective lengths and slenderness ratios of an unstiffened web acting as a column |
| 125 | Figure K.1 — Stress dispersion: buckling |
| 126 | Figure K.2 — Stress dispersion: bearing |
| 127 | Figure K.2 — Stress dispersion: bearing |
| 128 | K.3 Design of bearing stiffeners Load�bearing stiffeners should, wherever possible, be symmetrical about the web. Where the concen… The effective length of the equivalent strut, The outstanding legs of each pair of load�bearing stiffeners should be so proportioned that the p… Load�bearing stiffeners should be fitted to provide a tight and uniform bearing upon the flange t… Where the load or reaction can act eccentrically only to the web, or where the centroid of the st… K.4 Hollow sections Table K.2 — Effective lengths of load-bearings Annex L (informative) Effective lengths of steel members in compression L.1 General L.2 Effective length for axial compression |
| 129 | Figure L.2 — Positional restraint of steel members in axial compression |
| 130 | Table L.1 — Effective lengths of struts |
| 131 | L.3 Effective length for simply supported or continuous beams Beams with intermediate lateral restraints Beams without intermediate lateral restraints L.4 Effective length for cantilever beams Cantilevers with intermediate restraints Table L.2 — Effective lengths for beams without intermediate lateral restraint Cantilevers without intermediate restraints L.5 Effective torsional end restraint |
| 132 | L.6 Effective lateral restraint General Girder restraint bracing design Girder restraint from external points |
| 133 | Table L.3 — Effective length for cantilever beams without intermediate lateral restraint |
| 134 | Figure L.2 — Girder restraint (1) Figure L.3 — Girder restraint (2) |
| 135 | Annex M (informative) Selection of propping and repropping procedures for multi-storey buildings M.1 General M.2 Procedures |
| 136 | M.3 Examples |
| 137 | Table M.1 — Two Lifts of popping with repropping |
| 138 | Table M.2 — Two Lifts of popping with repropping |
| 139 | Table M.3 — Two Lifts of popping with repropping |
| 140 | Table M.3 — Two Lifts of popping with repropping |
| 141 | Annex N (informative) Bibliography |
