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This standard applies to the construction of cast-in-place reinforced concrete structures for buildings and structures. I. Construction preparation 1. Materials (1) Wooden formwork (or plywood): Wooden formwork (or plywood) should preferably be made of pine or fir of grade I or II, as well as plywood, and must comply with the relevant provisions in the \"Code for Construction and Acceptance of Wood Structures\" GBJ206-83 and the \"Code for Design of Wood Structures\" GBJ5-88. ⑵Timber beams: Timber beams should be made of pine or other suitable woods of grade I or II, and must comply with the relevant provisions specified in the \"Code for Construction and Acceptance of Timber Structures\" GBJ206-83 and the \"Code for Design of Timber Structures\" GBJ5-88. ⑶Support system: Wooden supports (pine or fir) as well as steel portal frames, steel pipes, etc., and shall comply with the relevant provisions in the \"Code for Construction and Acceptance of Timber Structures\" GBJ206-83, the \"Code for Design of Timber Structures\" GBJ5-88, and the \"Fasteners for Steel Pipe Scaffolds\" JGJ22-85. 2. Working Conditions (1) Selection of formwork structure: The structure of the formwork and the formwork support systems, as well as the construction plan, should be determined by conducting a comprehensive comparison based on the characteristics of the engineering structure, its planar geometry, the construction machinery and equipment available, and the availability of materials for the formwork and support systems. The best structural design and construction plan should be chosen, with the operating procedures and processes specified in that plan. ⑵Preparation of wooden formwork: The number of formworks should be determined through comprehensive consideration of the formwork design plan, as well as the division of construction phases outlined in that plan, in order to establish an appropriate quantity of formworks. ⑶Apply a release agent to the templates, and stack them neatly in accordance with the specified locations indicated in the construction layout plan. ⑷Before installing the formwork, the longitudinal and transverse axes (or center lines) as well as the edges of the formwork should be marked in accordance with the requirements of the design drawings, and the horizontal control elevation should be determined. ⑸Before starting template construction, the concealed work acceptance procedures for the previous process’s sub-projects or individual tasks must be completed. ⑹Before the installation of the formwork, conduct safety and technical briefings for the work team in accordance with the requirements of the formwork and drawings, as well as the standard operating procedures. II. Construction Procedures 1. Fabrication and Installation of the Foundation Formwork ⑴ Installation Sequence Setting out lines → Installing the bottom layer formwork → Installing supports for the bottom layer → Installing the upper layer formwork → Installing enclosures and supports for the upper layer → Setting up formwork hangers → (Installing the cup-shaped core formwork) → Inspection and adjustment → Acceptance Note: The procedures in parentheses apply only to the installation of cup-shaped foundation formwork. ⑵Stepped independent foundation: Fabricate formwork for each step according to the dimensions shown in the drawings. The formwork is installed layer by layer from bottom to top; first, the formwork for the bottom layer is installed, and it is secured in place using diagonal braces and horizontal supports ； Check the ink lines and elevations of the formwork, coordinate with the binding of rebar and the use of concrete (or mortar) pads, then proceed with the installation of the next layer of formwork. Recheck the dimensions and elevations of all areas indicated by the ink lines, and secure the diagonal braces, horizontal supports, and tie rods firmly. Finally, verify that the diagonal braces and tie rods are stable, and check the geometric dimensions, elevations, and axis positions of the foundation formwork. ⑶Cup-shaped independent foundation: Its construction process is similar to that of the stepped foundation, with the difference being that a central cup core form is added. The opening of the cup is larger at the top and smaller at the bottom, and it is slightly inclined. Before installing the core form, it must be assembled into a single unit, with bolts used to secure it on both sides. Once the central cup core form is in place, it is necessary to thoroughly check the elevation of the cup’s bottom, as well as the accuracy of all dimensions and the stability of the supports. ⑷Reinforcement form for strip foundations: After the side panels and end plates are fabricated, the outline of the foundation and its center line should first be marked on the bottom surface of the foundation. The side panels and end plates are then aligned with these lines, and a level is used to ensure that the top surfaces of the side panels are level. Once no errors are detected, the structure is secured in place using diagonal braces, horizontal braces, and tie rods. Finally, verify the geometric dimensions and axis positions of the base template. 2. Column formwork ⑴ Formwork erection procedure Layout lines → Set positioning references → Install the first piece of formwork in place → Install supports → Install the adjacent piece of formwork → Connect the two pieces of formwork and install supports for the second piece → Install the third and fourth pieces of formwork along with their supports → Straighten and correct any misalignments → Install column hoops → Conduct a thorough inspection and adjustment → Fix the entire set of column formwork → Remove debris from within the formwork and seal any access openings. ⑵After making the column side formwork according to the dimensions shown in the drawings (note: the width of the outer panels should be twice that of the inner panel thickness), mark the positions of the columns at floor level, fix foot plates at those locations, and then install the column formwork; two vertical supports along with diagonal bracing bars should also be used. After the column formwork is installed, it is necessary to thoroughly check items such as the verticality of the formwork, the difference in diagonal lengths, and the cross-sectional dimensions. The column formwork support must be secure; embedded parts and pre-drilled holes must not be omitted and must be accurate and firmly in place. ⑶Installation of column hoops: The installation of column hoops should be carried out from bottom to top. These hoops need to be selected based on factors such as the dimensions of the column formwork, the height of the column, and the level of lateral pressure (options include wooden hoops, steel hoops, and steel-wood hybrids). The spacing between column hoops is generally between 40 and 60 cm; when the cross-section of the column is large, core screws should be used, with their diameter and spacing determined through calculations. 3. Beam formwork installation (1) Installation procedure Marking lines → Setting up the formwork support frame → Installing the bottom formwork for the beam → Creating a camber in the beam formwork → Binding the rebar and using spacers → Installing the formwork on both sides → Fixing the beam clamps → Installing the formwork for the beam-column joints → Checking and adjusting → Installing the end clamps for the beam → Fixing adjacent beam formworks (2) Marking the axis lines, beam positions, and horizontal lines on the columns, then installing the column top formwork. ⑶Beam bottom formwork: Adjust the elevation of the supports to the design elevation, then install the beam bottom formwork and use tension lines to level it. When the span of the beam bottom slab is ≥ 4 m, the beam bottom at the mid-span should be arched in accordance with the design requirements; if no such requirements are specified in the design, the arching height should be 1–3‰ of the total span length. At the junction of the main beam and the secondary beam, the main beam should be arched first, followed by the secondary beam. ⑷When the pillars under the beam are supported on the foundation soil, the soil should be leveled and compacted to meet the bearing capacity requirements; effective measures such as wooden pads or concrete pads should also be used to ensure that the concrete does not settle during pouring. ⑸When the support is at a floor height of 3.8m or less, 1 to 2 horizontal tie rods and diagonal bracing should be installed; if the floor height is above 3.8m, a separate scaffolding installation plan must be developed in accordance with the company’s relevant regulations. ⑹Beam side formwork: Install the beam side formwork, foot plates, diagonal bracing, etc., according to the marked lines. The height of the formwork on the beam sides should be determined based on the beam height and whether the floor formwork abuts against or presses against them. ⑺When the beam height exceeds 70 cm, reinforcement with beam-through bolts should be added to the side formwork of the beam. 4. Floor formwork ⑴ Installation procedure Check the elevation of the bottom of the slab → Set up the formwork support frame → Place the ribs → Install the formwork (for ribbed floor slabs) → Install the formwork for column, beam, and slab joints → Place the formwork for embedded components and pre-drilled holes, etc. → Inspect and adjust → Submit for acceptance ⑵ Set up the pillars and ribs according to the formwork layout diagram. The spacing between the struts and the keel should be determined in the formwork design, based on the weight of the concrete in the formwork and the magnitude of the construction loads. The height of the main pillars is generally 80–120 cm, the spacing between the larger beams is 60–120 cm, and the spacing between the smaller beams is 40–60 cm. When arranging the pillars, it is necessary to take into account the need for construction access paths. ⑶The underlying ground is compacted in layers, and footings are laid. When using multi-layer support systems for formwork, the supports should be vertical, and the supports of upper and lower layers should lie on the same vertical center line. The horizontal tie rods and diagonal bracing between the pillars in each layer must be properly strengthened. ⑷Adjust the height of the support pillars by running wires, level out the main keel, and install the secondary keels. ⑸When laying the formwork, it can be started from the edges and brought together in the center. When under compression, the corner template should be secured with wire nails. ⑹After the floor formwork is installed, the elevation of the formwork surface and the flatness of the slab surface should be checked; embedded parts and pre-drilled holes must not be omitted and should be in the correct positions. The formwork support must be stable and secure. The surface of the formwork beams and slabs should be cleaned thoroughly. III. Quality Standards 1. Guaranteed Items (1) The formwork and its supports must possess sufficient strength, stiffness, and stability; the supporting parts of these supports must have a sufficient bearing area. If installed on bed soil, the bed soil must be solid and have proper drainage. ⑵Wooden formwork (or plywood) shall meet the material selection standards for load-bearing structures specified in the \"Code for Construction and Acceptance of Wood Structure Projects\" (GBJ206-83). The type of wood can be chosen based on the local conditions, provided that the quality of the wood is not lower than grade III. 2. Basic requirements (1) The width of the template joints shall meet the following specifications: Acceptable: not more than 2.5 mm Excellent: not more than 1.5 mm (2) The contact surface between the template and the concrete must be cleaned thoroughly, and measures should be taken to prevent adhesion. 1) The cumulative area of paste applied on the formwork of each plate (unit) and the area where the sealant was not applied properly shall comply with the following specifications. Qualified: not more than 2000 c㎡ Excellent: not more than 1000 c㎡ 2) The total area of adhesive on the formwork of each beam or column, as well as any areas where the sealant was not applied, shall comply with the following specifications. Qualified: not more than 800 c㎡ Excellent: not more than 400 c㎡ 3. Permissible deviations The permissible deviations for template installation, as well as for embedded parts and pre-existing holes, shall comply with the requirements specified in Table 5-1. IV. Construction precautions 1. Avoiding common quality issues in projects (1) Before installing the templates, check their quality first; those that do not meet the quality standards shall not be put into use. ⑵Basic formwork: 1) For strip foundations, it is necessary to prevent situations where the top edge of the formwork is not straight along the length of the foundation, where the width is incorrect, where the bottom edge sinks into the concrete, where the upper portion of the concrete is damaged during formwork removal, and where the lower formwork is not secure in place. Preventive measures: a) The formwork must have sufficient strength and stiffness, and its verticality must be accurate when it is set up. b. Wooden strips should be nailed at the top of the formwork to control the width of the top edge of the strip foundation, and tension rods should be used throughout to ensure that the top edge remains straight. c. At regular intervals, support the lower edge of the upper section of the formwork on the steel hoop supports ； Temporary wooden braces can also be used to maintain a consistent height for the side formwork. d、When the support is placed directly against the edge of the pit, wooden planks should be placed underneath to increase its bearing surface. Splices should be added at the longitudinal joints of the two templates to ensure a flat plate surface and a secure connection. 2) The cup-shaped foundation should prevent misalignment of the center line and displacement of the cup mouth formwork ； The core form rises during concrete pouring, and it cannot be removed after the formwork is taken down. Preventive measures: a. When setting up the formwork for the cup-shaped foundation, it is necessary to ensure that the centerline and elevation are accurate. When installing the upper section of the formwork, the use of jacks helps to maintain accuracy; the supporting pieces serve to keep the jacks at a slight distance from the lower concrete surface, which facilitates leveling of the concrete surface. b. The core template should be sanded smooth and joined directly; an isolation agent should be applied to its outer surface, and several small holes should be drilled at the bottom to allow exhaust and reduce buoyancy. c. When pouring concrete, the material should be distributed evenly around the core formwork, and vibration should be applied properly. d. Scaffolding planks must not be placed on formwork. e. The removal of the cup core formwork should be determined based on the temperature during construction and the setting condition of the concrete; generally, it can be gently struck with a hammer or pulled out using a pry bar around the time when the concrete begins to set. ⑶Beam formwork: to prevent the beam from being uneven, the bottom of the beam from not being level or from sagging, the side formwork of the beam from failing, and local sections of the formwork from embedding between columns and beams ； The phenomenon of difficult demolition. Preventive measures: a. When formulating the supports for beams, it is necessary to follow the principle of using side forms to enclose the bottom form. At the junctions between beam forms and column forms, account must be taken of the longitudinal expansion that occurs when the beam forms absorb moisture; therefore, the dimensions of the forms should generally be slightly reduced, so that the concrete does not get trapped inside the columns after pouring. b. The formwork on the sides of the beam must be equipped with foot plates and diagonal braces; after these are in place, the sides of the beam should be secured with nails. The formwork at the bottom of the beam must be arched as specified. c. Before pouring the concrete, the formwork should be thoroughly moistened with water. ⑷Column formwork: Prevents issues such as the formwork bursting, the cross-sectional dimensions expanding, leakage of concrete, uneven density of the concrete mixture, as well as honeycombing, pitting, and twisting of the column shaft. Preventive measures: a. Drive the studs firmly in accordance with the specified spacing requirements. b. When setting up the column formwork in rows, first erect the formwork for the end columns; after ensuring they are straight and in the correct position, pull a string across the top before erecting the formwork for the middle columns. c. The diagonal braces around should be secure. d. For taller columns, a temporary pouring hole should be left on one side of the formwork to facilitate concrete pouring and the insertion of a vibrator; once the concrete reaches the temporary hole, it should be sealed tightly. ⑸Slab formwork: Prevents sagging in the middle of the slab and unevenness of the concrete surface at the bottom of the slab. Preventive measures: a. The thickness of the floor formwork should be consistent; the grating wood must have sufficient strength and stiffness, and its surface should be flat. b. The supporting materials must have sufficient strength, and they should be securely connected to each other in all directions; the support system must be stable. c. The formwork shall be cambered as specified. 2. Main safety technical measures (1) Safety operating procedures must be followed during the formwork erection process. In case of a pause during work, the already installed supports and formwork connections must be secured firmly; they must not remain unsupported or floating. During the demolding interval, the loose components and formwork should be removed to prevent them from falling and causing injury. ⑵Scaffolding should be set up when removing formwork. ⑶When removing the formwork on the outside of a floor, measures should be in place to prevent falls from heights and to stop the formwork from falling outward. 3. Finished product protection ⑴ Always clean the surface of the formwork after each use and apply a release agent. ⑵Reinstall layer by layer according to the floor slab locations to reduce losses. ⑶Materials should be neatly stacked in categories at the locations specified in the layout plan.