This British Standard gives recommendations and guidance on the procedural controls to be applied to all aspects of temporary works in the construction industry. It also includes guidance on design, specification, construction, use and dismantling of falsework. This standard gives guidance on permissible stress design of all falsework. The guidance also applies to the design of class A falsework¹ defined in BS EN 12812, the design of which is specifically excluded from BS EN 12812.

Section 1 gives recommendations in relation to training and education.

Section 2 gives recommendations for procedures to ensure that temporary works are conceived, designed, specified, constructed, used and dismantled all in a safe and controlled manner suitable for all construction projects. These procedures include clauses relating to all roles involved in temporary works: clients, permanent works designers, temporary works designers, contractors (including construction management organizations), suppliers and manufacturers.

Construction sites and methods adopted for controlling the temporary works vary. This British Standard recognizes that the extent of control measures required are greater on the larger or more complex projects, as can be encountered on major infrastructure projects, power stations, airports etc. Generally procedures are to be in accordance with this standard but additional client specific procedures might be required on major infrastructure projects.

Section 3 covers the design of temporary works and in particular the design of falsework and relevant formwork. In addition Section 3 covers: materials including material factors; loads and load factors; design of falsework, including both proprietary equipment and traditional scaffolding solutions; wind loading (reference to temporary and permanent stability) and reference to other British Standards for the design of structural steelwork, reinforced concrete and excavation support. Although Section 3 was written for permissible stress design, the design concepts and the service loads stated are applicable to limit state design. The loads, including wind loads, are the unfactored service loads and conform to both BS EN 1991‑1‑4 and BS EN 12812.

The structural design element in this British Standard is additional information necessary for the structural design of falsework. It can be used in conjunction with existing structural standards.

BS EN 12812 states that design class A is only to be adopted where:

a) slabs have a cross-sectional area not exceeding 0.3 m² per metre width of slab;

b) beams have a cross-sectional area not exceeding 0.5 m²;

c) the clear span of beams and slabs does not exceed 6.0 m;

d) the height to the underside of the permanent structure does not exceed 3.5 m.

PDF Catalog

PDF Pages	PDF Title
9	Foreword
11	Introduction
12	Section 1: General 1 Scope 2 Normative references
14	3 Terms and definitions
19	4 Abbreviations and symbols
23	5 Overview of temporary works procedures and training 5.1 Overview of procedures
27	Figure 1 — Typical contractual interfaces between parties on a project
29	Figure 2 — Lines of responsibilities where a single contractor or a principal contractor (PC) is co-ordinating the temporary works
31	Figure 3 — Lines of responsibility where either a principal contractor’s (PC) appointed sub-contractor or a client’s contractor co-ordinate their own temporary works
32	Figure 4 — Schematic representation of relationships between principal contractor and contractor (client appointed or sub-contractor) including PC’s TWC and contractor’s TWC
33	5.2 Training
35	Section 2: Procedural control of temporary works 6 Procedures 6.1 Introduction to procedural control
38	Table 1 — Implementation risk classes for temporary works and examples of mitigation measures
39	6.2 Temporary works register
40	7 Clients’ procedures 7.1 General (Commercial/public clients)
41	7.2 Clients appointing contractors other than PCs 7.3 Client’s DI
42	7.4 Domestic clients
43	8 Designers’ procedures 8.1 General
44	8.2 Designers’ DI 8.3 Permanent works designers
45	8.4 Temporary works designers 8.5 Principal designers
46	9 Contractors’ procedures 9.1 Organizational interfaces
47	9.2 Contractors’ DI
48	9.3 Responsibilities
50	9.4 Principal contractor
51	9.5 Contractors other than PC
52	9.6 Third-party employed contractor 10 Supplier/manufacturer procedures 10.1 Suppliers of temporary works equipment 10.2 Suppliers’ DI
53	10.3 Suppliers’ procedures 10.4 Verification of design information 10.5 Provision of information 10.6 Provision of design data
54	10.7 Provision of information for the safe use of equipment 10.8 Standard solutions 11 Temporary works co-ordinator 11.1 General 11.2 The PC’s TWC
57	11.3 The TWC (other than the PC’s TWC)
60	12 Temporary works supervisor 12.1 General 12.2 Role of the TWS
61	12.3 Duties of the TWS 13 Design of temporary works 13.1 General
62	13.2 Design brief
63	13.3 Design guidance
65	13.4 Choice of temporary works 13.5 Selection of materials and components 13.6 Design output
66	13.7 Design check
67	Table 2 — Categories of design check in temporary works
68	13.8 Resolution of queries raised by the design checker
69	13.9 Alterations 13.10 Standard solutions
70	14 Site considerations 14.1 Co-ordination, supervision and checking of work on site
71	14.2 Loading and unloading temporary works
72	14.3 Dismantling
73	Section 3: Falsework 15 General 16 Materials 16.1 General considerations 16.2 Testing and inspection
74	16.3 Steelwork (other than scaffold tube)
75	16.4 Timber
76	Table 3 — Basic stresses and moduli of elasticity for the wet condition Table 4 — Softwood species which satisfy strength classes in accordance with BS 4978
77	Table 5 — North American softwood species and grade combinations which satisfy strength classes in accordance with national lumber grades authority (NLGA) and national grading rules for dimension lumber (NGRDL) joist and plank rules Table 6 — Hardwoods which satisfy the strength classes graded to BS 5756:2007
78	Table 7 — Preferred target sizes and actual dimensions for constructional sawn softwood timber
79	Table 8 — Modification factor K3 for duration of load on falsework
80	Table 9 — Modification factor K4 for bearing stress Table 10 — Maximum depth-to-breadth ratios
81	Figure 5 — Shear stress on a timber beam of rectangular cross-section
82	Table 11 — Depth modification factor K7 for solid timbers less than 300 mm depth
83	Table 12 — Permissible stresses and moduli of elasticity for general falsework applications Table 13 — Permissible stresses and moduli of elasticity for load-sharing falsework applications
84	Table 14 — Commercial grade timber suitable to produce mainly class C16 timber 16.5 Concrete and concrete components
86	16.6 Brickwork and blockwork 16.7 Other materials
87	16.8 Steel scaffold tubes, couplers and other fittings
89	16.9 Manufactured components for falsework
90	Table 15 — Adjustable steel prop heights
91	Figure 6 — Safe working loads for BS 4074:1982 props erected 1.5° out-of-plumb
92	Figure 7 — Safe working load for BS 1065:1999 props erected 1° maximum out‑of‑plumb and with up to 10 mm maximum eccentricity of loading
93	17 Loads applied to falsework 17.1 General
94	17.2 Weights of materials 17.3 Self-weights 17.4 Imposed loads
97	17.5 Environmental loads
101	Figure 8 — Fundamental basic wind velocity vb,map (in m/s)
102	Figure 9 — Topography factor Twind diagram
103	Table 16 — Combined exposure factor, ce(z)ce,T
104	Figure 10 — Displacement height diagram Figure 11 — Town, country and sea
107	Table 17 — Force coefficients cf for falsework
109	Figure 12 — Wind on soffit parallel to secondary bearers Figure 13 — Wind on soffit parallel to primary bearers
111	Figure 14 — Wind on two edge forms Figure 15 — Shelter factor
112	Figure 16 — Wind on more than two edge forms
113	Figure 17 — Wind loading – Combined formwork and unclad falsework (upper limit)
120	18 Foundations and ground conditions 18.1 General 18.2 Site investigation for falsework foundations
121	Table 18 — Presumed allowable bearing pressure under vertical static loading
122	18.3 Testing of soils
123	Table 19 — Identification and description of soils 18.4 Allowable bearing pressures
124	18.5 Modification factors applied to presumed bearing pressures
125	Table 20 — Ground water level modification factor 18.6 Simple foundations on sands and gravels 18.7 Simple foundations on cohesive soils 18.8 Heavy vibrations 18.9 Fill material
126	18.10 Piles 18.11 Protection of the foundation area 19 Design of falsework 19.1 Preamble to design
128	Figure 18 — Individual support members
129	Figure 19 — Panels to facilitate the erection of individual prop systems (elevation) Figure 20 — Individual fully braced tower Figure 21 — Proprietary system, partially braced by discrete panels
130	Figure 22 — Fully braced falsework system
131	19.2 Forces applied to falsework
133	19.3 Analysis of the structure
135	Figure 23 — Free-standing structure Figure 24 — Top-restrained structure
136	Figure 25 — Plate action (plan view)
137	Figure 26 — Restraint provided on one side of the plate (plan view) Figure 27 — Restraint provided on two perpendicular sides of the plate (plan view) Figure 28 — Restraint provided on two parallel (opposite) sides of the plate (plan view)
138	Figure 29 — Restraint provided on three sides of the plate (plan view) Figure 30 — Restraint provided on four sides of the plate (plan view) Figure 31 — Restraint provided by four permanent works columns (plan view) Figure 32 — Restraint provided by two permanent works columns (plan view)
139	Figure 33 — Concrete pressures applied and the subsequent rotational forces induced (typical falsework plan)
141	Figure 34 — Effects of eccentricity and sway on top-restrained structures Figure 35 — Effects of eccentricity and sway on freestanding structures
142	Figure 36 — Effects of FH on individual towers
143	Table 21 — Example of percentage of load transfer for less than 350 mm flat slabs 19.4 Design
144	Table 22 — Roles and responsibilities of temporary and permanent works designers
145	Table 23 — Requirements for stability checks in top-restrained falsework
146	Table 24 — Requirements for stability checks in free-standing structures
148	Figure 37 — Typical, free-standing, fully braced scaffolding (elevation) Figure 38 — Typical, top-restrained, fully braced scaffolding (elevation)
150	Figure 39 — Member stability check for top-restrained systems (elevation) Figure 40 — Considerations for partially braced frames
151	Figure 41 — Member stability check for free-standing systems (elevation)
152	Figure 42 — Considerations for free-standing partially braced frames
153	Figure 43 — Effective lengths in tube and coupler falsework
154	Figure 44 — Lateral stability check for top-restrained structures
155	Figure 45 — Lateral stability check for free-standing structures
156	Figure 46 — Working space and stability during erection, loading and dismantling
158	Figure 47 — Lateral restraint provided by friction
159	Table 25 — Recommended values of coefficient static friction μ
160	19.5 Beams and lattice girders 19.6 Foundations
163	Figure 48 — Base detail on slopes
164	19.7 Additional considerations affecting certain design solutions
165	Figure 49 — Suggested bracing arrangement for falsework erected on beams or girders
167	Figure 50 — Maximum deviation of load path
168	20 Work on site 20.1 Introduction 20.2 Specific design instructions 20.3 General workmanship
171	Figure 51 — Points of measurement of tolerances for purposely fabricated steelwork
172	Figure 52 — Skew lapping of primary beams to minimize eccentricity of load
173	20.4 Checking falsework
175	20.5 Application of loads to falsework 20.6 Dismantling
176	20.7 Maintenance, inspection and identification of materials
177	Annex A (normative) Permissible stresses and modulus of elasticity for steel grades generally used in falsework
178	Figure A.1 — I beam dimensions
179	Table A.1 — Permissible bending stress in compressive members, pbc, for beams
180	Table A.2 — Permissible axial compressive stress, pc, on cross-section Annex B (normative) Properties of components in tube and coupler falsework
183	Table B.1 — Section properties of scaffold tube
184	Table B.2 — Safe axial loads in compression for Type 4 steel scaffold tubes manufactured in accordance with BS EN 39:2001
185	Table B.3 — Safe axial loads in compression for Type 4 steel scaffold tubes manufactured in accordance with BS 1139‑1:1982
186	Table B.4 — Safe working loads for individual couplers and fittings Annex C (normative) Initial testing, quality control and inspection of falsework equipment
188	Annex D (normative) Data on material properties Table D.1 — Modulus of elasticity for concrete
189	Table D.2 — Density of reinforced concrete Table D.3 — Density ranges for lightweight concretes
190	Table D.4 — Masses of scaffolding material Table D.5 — Masses and densities of men and materials Table D.6 — Masses of corrugated steel sheeting
191	Annex E (normative) Wave forces
193	Figure E.1 — Non-breaking waves – Section diagrams Annex F (normative) Site investigations for foundations for falseworks
195	Annex G (informative) Examples of design brief contents
197	Annex H (informative) Forces from concrete on sloping soffits Figure H.1 — Distribution of forces on sloping soffits – Level surface, sloping base
198	Figure H.2 — Distribution of forces on sloping soffits – Sloping surface and sloping base Figure H.3 — Distribution of forces on sloping soffits – All surfaces sloping and with top formwork
199	Figure H.4 — Freestanding falsework
200	Figure H.5 — Formwork connected to an existing structure Figure H.6 — Arch falsework Annex I (informative) Blank
201	Annex J (normative) Design of steel beams at points of reaction or concentrated loads
203	Table J.1 — Effective lengths and slenderness ratios of an unstiffened web acting as a column
204	Figure J.1 — Stress dispersion – Buckling
205	Figure J.2 — Stress dispersion – Bearing
207	Table J.2 — Effective lengths of load bearings Annex K (normative) Effective lengths of steel members in compression
208	Figure K.1 — Positional restraint of steel members in axial compression
209	Table K.1 — Effective lengths of struts
210	Table K.2 — Effective lengths for beams without intermediate lateral restraint
212	Table K.3 — Effective lengths for cantilever beams without intermediate lateral restraint
213	Figure K.2 — Girder restraint (1) – Plan view
214	Figure K.3 — Girder restraint (2) – Plan view Annex L (informative) Wind calculations for falsework
215	Table L.1 — Source of the basic wind equations
217	Table L.2 — Values of direction factor, cdir
222	Table L.3 — Combined roughness factor, cr(z)cr,T
223	Table L.4 — Turbulence intensity, Iv(z)flat
224	Figure L.1 — Orography factor, co
228	Annex M (normative) Shielding factor η for unclad falsework Table M.1 — Shielding factor, η
230	Bibliography
234	Index

Published By	Publication Date	Number of Pages
BSI	2019	250


PDF Format	Searchable	Printable	Preview Now

Status	Under Review
Pages	250
Publication Date	2019-05-30
ISBN	978 0 580 96022 2
Standard Number	BS 5975:2019
Title	Code of practice for temporary works procedures and the permissible stress design of falsework
Replaces	BS 5975:2008+A1:2011
Descriptors	Modulus of elasticity, Structural design, Temporary structures, Dimensions, Climatic loading, Density, Visual inspection (testing), Hardwoods, Props, Ground-water drainage, Traffic, Supports, Stress analysis, Structural systems, Bending stress, Struts, Legislation, Loading, Design, Softwoods, Steels, Structural timber, Building sites, Brickwork, Field testing, Site investigations, Axial stress, Mechanical properties of materials, Structural members, Erecting (construction operation), Independent scaffolds, Foundations, Beams, Soils, Falsework, Stability, Factor of safety, Soil testing, Maintenance, Structural steels, Mobile scaffolds, Girders, Bailey bridges, Concretes, Strength of materials, Blocks (building), Scaffolding components, Mass, Wind loading
Publisher	BSI
Committee	B/514/26
ICS Codes	91.220 - Construction equipment

BS 5975:2019

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BS 5975:2019 – TC