The steel truss formwork is made by welding the upper and lower longitudinal steel bars (upper and lower chords) in the cast-in-place concrete floor slab with the bent small-diameter steel bars (webs) to form a structure with a certain stiffness and ability to The small truss that bears the load is then welded to a profiled steel plate with a rib height of only 2 mm and a plate thickness of 0.4 to 0.6 mm. The processing operations are all completed in the factory using automated production lines.
Construction of steel truss formwork: The steel bars in the floor slab are processed into steel trusses, and the steel trusses and galvanized steel plates are welded into one body.
Trusses composed of steel bars bear the load during construction, and galvanized steel sheets are used as formwork during concrete pouring. See the picture
Reinforcement truss formwork picture
The bottom surface treatment of the steel truss formwork: hot-dip galvanizing.
1 Main technical content
1) Design of steel truss formwork
During the process of concrete pouring and reaching the design strength, the stress on the floor is obviously different, so it should be carried out Calculation in two stages: use and construction. The use phase is generally implemented according to the design of the design institute; the construction phase requires in-depth design of the following contents:
(1) Check the strength of the upper and lower chords of the steel truss, the stability of the compression chords and webs, and the deflection of the truss , to determine whether span supports are needed.
(2) Construction layout design of steel truss formwork, and CAD layout based on actual structural dimensions.
2) Construction process flow
Construction layout design of steel truss formwork → Construction preparation → Hoisting and temporary setting → Installation of steel truss formwork → Bolt welding → Pipeline laying → Steel bar binding → Edge Formwork installation → acceptance → concrete pouring → concrete curing.
3) Key points for the installation of steel truss formwork
(1) Set angle steel supports at special-shaped places such as column edges, and complete the angle steel supporting the steel truss formwork in the core tube part.
(2) Set the baseline for laying the steel truss formwork.
(3) The installation of steel truss formwork should be carried out after the next section of steel columns and supporting steel beams are installed.
(4) Align the base line, install the first board, and install other boards in sequence. The steel truss formwork is connected by snap-fitting, and the hook connection between the boards should be tight to ensure the pouring of concrete. There should be no leakage of slurry, and the direction of plate arrangement should be consistent.
(5) After the steel truss formwork is in place, immediately spot weld the vertical steel bars at its ends to the steel beams firmly, and tie the distribution bars in time to prevent lateral instability of the steel truss.
(6) The side formwork is a key component to prevent concrete leakage and is made of 2mm galvanized steel plate. After the side formwork is straightened and adjusted properly, one end of the steel bar is spot welded to the stud and the other end is spot welded to the side formwork to fix the side formwork. The sealing method is as shown in the figure
Side form sealing diagram
(7) In order to make the steel beams and composite floor slabs work together effectively during the project, shear connection bolts are set , so that the stud rod can bear the shear force between the steel component and the concrete to achieve a steel-concrete shear connection.
(8) When pouring concrete, set supports at corresponding designated locations according to design requirements. The supports can only be removed after the strength of the board reaches the design requirements.
2 Technical indicators
1) Specifications of steel truss formwork: executed as designed. The allowable deviations of width and length are shown in the table
2) The allowable deviations of the truss structural dimensions are shown in the table
3) The flatness of the straight part of the bottom mold and the overlapping edge per meter should not be greater than 1.5mm.
4) The number of solder joints falling off or missing in each finished product shall not exceed 4 of the total number of solder joints, and two adjacent solder joints shall not have missing solder joints or fall off.
5) The overlap length of the steel truss formwork should meet the design requirements, and the overlap length should not be less than 50mm. The overlap length between the bottom galvanized steel plate and the steel beam must be sufficient to prevent leakage of slurry when pouring concrete, and the overlap length should not be less than 30mm.
6) Reference values ??of bolting process parameters are shown in the table
3 Scope of application
Applicable to steel-concrete composite floor projects of steel frame structures.
For more information about engineering/service/purchasing tender document writing and production to improve the bid winning rate, you can click on the official website customer service at the bottom for free consultation: /#/?source=bdzd