Construction requirements 5.1 Reinforcement fabrication and installation 5.1.1 Reinforcement processing 5.1.1.1 Reinforcement blanking and quality requirements The technical department of the beam yard shall issue a blanking sheet according to the construction drawings, and the blanking personnel shall test the bending according to the blanking sheet.
After the bending test is qualified and signed by the person in charge, normal blanking can be started.
The pouring method is: longitudinal segmentation, oblique layering, and gradual construction from one end to the other.
(2) The concrete must have the strength and elastic modulus that meet the design requirements, and have the ability to prevent alkali aggregate reaction.
The concrete shall not be put into the mold if its performance does not meet the requirements.
Technical requirements (1) There must be general drawings approved by relevant departments or design drawings of the design institute, and construction drawings approved by the chief engineer.
The mixed concrete that cannot be poured immediately shall be covered to prevent wind, sun and rain.
5.1.2 binding of reinforcement the binding of reinforcement framework shall adopt the method of prefabricated pedestal binding or integral binding and integral lifting of binding pedestal according to the structural form and site conditions.
The size of each part must be tested for bending, and the extension value, bending radius, plate spacing, etc.
5.3 Concrete construction 5.3.1 Mixing of concrete Various raw materials for concrete mixing, such as sand, stone, cement, admixtures and fly ash, shall be inspected and confirmed as qualified before being put into use.
2.2 Collection of various external technical data involved in the field technical preparation construction layer.
Carry out technical disclosure to the construction personnel, carry out pre job technical training for the construction personnel, and take up their posts with certificates after passing the examination.
The overall arrangement shall be made according to the size of the feed to reduce the loss of the reinforcement.
Strictly control the water consumption according to the specified water cement ratio, do not add water arbitrarily, and pay attention to checking whether the subsidence meets the requirements regularly.
4.2 Process flow (see the figure below) Process flow chart of post tensioned beam fabrication 5.
Construction procedure and process flow 4.1 Construction procedure After the semi-finished reinforcement is prefabricated in the reinforcement workshop, the beam reinforcement shall be bound on the mold frame, the beam reinforcement shall be moved to the pedestal bottom formwork by the gantry crane, the steel formwork shall be erected, the upper panel reinforcement shall be installed, and the concrete shall be poured.
When mixing concrete in hot seasons, measures such as setting up sunshades in the aggregate yard, mixing concrete with low temperature water, etc.
(3) The concrete must have the strength, stiffness, crack resistance, durability and other technical indicators that meet the design requirements.
Operation preparation 2.1 after the preparation of the operation instructions for technical preparation of the office work, the technical personnel shall be organized to carefully study the practical construction organization design, read and review the construction drawings, clarify the relevant technical problems, and be familiar with the specifications and technical standards before commencement.
5.3.2 The concrete hopper shall be transported to the construction site by the mixer truck, and the height from the hopper outlet to the bearing surface shall not be greater than 2m.
5.3.3 Pouring of concrete The beam concrete shall be poured in a continuous manner.
When binding the lower flange stirrup, the overlapping position of the reinforcement shall be symmetrical and staggered, and the included angle on both sides of the intersection shall be equal.
The preheating method of heated water shall be preferred to adjust the temperature of the mixture.
If there is welding, it must be subject to welding inspection.
The intersection points at the corners shall be bound completely, and the intersection points of the middle straight part can be staggered.
Operation Instruction for Precast Beam Prefabrication 1.
Scope of Application This operation instruction is applicable to precast beam prefabrication.
(3) Stirrups made of plain round steel bars shall have hooks at their ends (semicircle, right angle or diagonal hooks); The bending internal diameter of the hook shall meet the requirements of the Inspection Standard.
of the test bending must be calculated.
2.
After the installation of reinforcement and prestressed pipe, check whether their positions are correct and whether the duct is smooth.
Build living houses, complete living and office facilities, and meet the needs of main management and technical personnel for living and office.
It shall be frost resistant, impermeable and corrosion-resistant according to the environmental category and erosion level.
It can be put into use only after passing the inspection after entering the site.
The wire binding head for binding reinforcement shall be pushed into the inner side of the framework.
5.1.1.2 reinforcement processing (1) before bending and forming, the specification, shape, size and bending sequence of the processed reinforcement shall be familiar with.
(2) After the bent semi-finished steel bars pass the inspection, they shall be stacked by category and labeled.
Formulate construction safety and environmental protection measures and emergency plans.
For each vibration, the web vibrator on the corresponding section shall be used according to the place where the concrete is poured, and the immersion vibrator shall be used for vibration..
The reinforcement framework shall be bound firmly without looseness and skewness.
The batch production can only be carried out after the test bending is qualified.
If there is any deviation, immediately adjust it until it meets the requirements.
Before mixing concrete in winter, the maximum preheating temperature of water and aggregate shall be determined through thermal calculation and trial mixing to ensure that the molding temperature of concrete meets the requirements.
(4) The allowable deviation of reinforcement processing shall meet the requirements of acceptance standard.
3.
5.2 The size and position of the reserved hole for the prestressed reinforcement in the installation of the hole making pipe shall be correct, the hole shall be smooth, and the longitudinal hole and the transverse hole shall meet the requirements of the design position.
After the horizontal reinforcement of the web is bound, the overall dimension and position of the reinforcement shall be adjusted.
shall be taken to reduce the temperature of concrete mixture, or concrete shall be mixed in the evening or evening as far as possible to ensure that the molding temperature of concrete meets the requirements.
(4) Ordinary reinforcement must have a raw material certificate.
(5) The prestressed tendon anchorage must have the raw material certificate, and can be put into use only after passing the inspection after entering the site.
4.
The label shall include: beam model and steel bar number.
The stirrup and the main reinforcement shall be vertically enclosed.
At the same time, carefully check whether the horizontal reinforcement, stirrup and connecting angle steel of the positioning net touch the rubber tube to prevent the rubber tube from being scratched when it is pulled out.
The discharge valve at the bottom of the hopper shall be easy to open and free from slurry leakage.
After mixing, the concrete shall be sent to the pouring site immediately.
The cutting edge of the structural reinforcement blanking shall be flat, Both ends shall not be bent.
