Detail of JGJ 74-2003

Introduction of JGJ 74-2003

1 General Provisions 1.0.1 In order to adapt the development of large-area formwork technology, and to make its design, fabrication and construction achieve advanced technology, economic rationality, safety and usability, and to ensure engineering quality, this Specification was formulated. 1.0.2 This Specification is applicable to the design, fabrication and construction of formwork of the on-site concrete engineering in the vertical structures of multilayer and tall building. 1.0.3 In addition to the requirements of this Specification, the design, fabrication and construction of large-area formwork shall meet the requirements of current relevant compulsory standards of the nation. 2 Terms and Symbols 2.1 Terms 2.1.1 Large-area formwork Large formwork with larger dimension and area of formwork and adequate bearing capacity, which is fully loaded and unloaded. 2.1.2 Entire large-area formwork Entire large-area formwork whose formwork dimension is arranged based on the concrete wall dimension. 2.1.3 Assembling large-area formwork Large formwork which is assembled based on the principle of the standard formwork which meets the requirements of building module as primary and non-standard formwork as secondary. 2.1.4 Surface panel Bearing plate which directly contacts with newly-poured concrete. 2.1.5 Rib The bearing member of supporting surface, which is divided into primary rib, secondary rib and side rib etc.. 2.1.6 Waling Supporting member of supporting member. 2.1.7 Tie bolt Special bolt which connects to the formworks on the both sides of wall, and bears the side pressure of fresh concrete. 2.1.8 Angle of self-stabilization The inclined angle which is formed from the large-area formwork balances the wind load by self weight to maintain self stability where the large-area formwork is vertical placed. 2.2 Symbols F——The maximum side pressure of newly-poured concrete against formwork; Hn——The design height of matching plate of internal wall formwork; Hw——The design height of matching plate of external wall formwork; hy——The height of available head; La, Lb, Lc, Ld——The design length of formwork matching plate Sd——The net sectional area of flying rings; α——Angle of self-stabilization. 3 Basic Requirements of Large-Area Formwork Composition 3.0.1 Large-area formwork shall be composed of surface panel system, supporting system, operating platform system and connecting pieces etc., and the schematic diagram is shown in Appendix A of this Specification. 3.0.2 The connection of the systems constituting the large-area formwork must be safe and reliable. 3.0.3 Steel plate with the thickness not less than 5mm shall be adopted for the fabrication of the surface panel of large-area formwork shall, and the material shall not be less than the performance requirements of Q235 A; section steel and cold-formed thin-wall steel shall be adopted for fabrication of the rib and waling of formwork, and the material should be with the same grade of steel surface panel material, to ensure welding property and structural property. 3.0.4 The supporting system of large-area formwork shall be able to maintain the safety and reliability the vertical placing of large-area formwork as well as the self-stability under the action of wind load. The length of tail margin adjusting bolt shall meet the requirements of adjusting the formwork installation verticality and angle of self-stabilization; base adjusting device shall be convenient for adjustment, and shall rotate flexibly. 3.0.5 The steel flying rings of large-area formwork shall be adopted Q235 A materials for fabrication and shall have adequate safe storage; cold-processed steel reinforcement must not be used. Welded type steel flying rings shall be selected reasonable electrode model, weld length and weld height, and shall meet the design requirements; double nuts must be adopted where fabricated flying rings and large-area formwork are connected with bolt. 3.0.6 The tie bolt material of large-area formwork shall be adopted steels not less than Q235 A for fabrication, and shall have adequate strength to bear construction load. 3.0.7 Integral-type lift shaft mould shall be able to support and dismantle conveniently, accurately positioned, and shall be installed with special operating platform to ensure safe construction. 3.0.8 Large-area formwork shall be able to meet the requirements of the forming of on-site concrete and the surface quality effect . 3.0.9 The structure of large-area formwork shall be simple, light, solid, durable, and easy for processing and fabrication. 3.0.10 Large-area formwork shall have adequate bearing capacity, rigidity and stability, and shall be able to load and unload in full seyt and be convenient for assembling, and it shall be able to repeatedly used in normal maintenance.

Contents of JGJ 74-2003

1 General Provisions 2 Terms and Symbols 3 Basic Requirements of Large-Area Formwork Composition 4 Design of Large-Area Formwork 5 Fabrication and Inspection for Large-Area Formwork 6 Construction and Acceptance of Large-Area Formwork 6.4 Acceptance Standard of Large-Area Formwork Installation Quality 6.5 Dismantling and Stacking of Large-Area Formwork 7 Transport, Repair and Storage 7.1 Transport 7.2 Repair 7.3 Storage Appendix A Schematic Diagram of Large-Area Formwork Composition Appendix B Load and Load Effect Combination of Large-Area Formwork Appendix C Design Values Of Strengths of Steel, Welding Seam Connection and Bolted Connection for Large-Area Formwork Appendix D Conversion Relation of Wind Force, Air Velocity and Basic Wind Pressure Explanation of Wording