Main Control Measures in Prestressed Construction – 1
Control the position of prestressed tendons
Lay the prestressed tendons in strict accordance with the design requirements, and ensure the accurate position, so as to achieve non-twisting and straight planes. When setting the stressing end, the prestressed tendons and the anchor heads should be vertical, and the pressure-bearing bar after the column is installed should be fixed firmly to prevent displacement when pouring the concrete. When there are holes and reserved holes, the prestressed tendons shall be continuous and not around, and they shall be arranged 30mm away from the side of the holes. When the prestressed tendons conflict with non-prestressed tendons or other pipes, ensure that the prestressed tendons are laid according to the designed position, and make appropriate adjustments to the position of the steel bars. No matter how the adjustment is made, it is strictly forbidden to cut off the steel bars. If there is a large displacement of the steel bars in the two parts during the actual construction, we can reinforce this part with a grid-beam structure.
The important basis for ensuring the quality of the prestressing system is the installation quality of the prestressing tendons and corrugated ducts. The construction process must be strictly controlled. Only in this way can it be ensured that the wave pipes will not be blocked, leaked, deformed, or displaced after pouring concrete.
Strictly check the corrugated ducts before use to see if it is damaged. If it can be repaired, it can be repaired in time. If it cannot be repaired, it should be discarded. The burr, curling, and corner of the corrugated duct end must be removed before installation. Make the position of the corrugated duct accurate, prevent left and right movement, floating and sinking, and control the position deviation within the specification requirements.
The gap between the steel mesh and the corrugated duct should be less than 3mm; Set according to the distance between the curve section not greater than 0.5m and the straight section not greater than 1m; When electrical welding is performed near the pipeline, the corrugated duct must be covered with wet sacks or thin iron sheets to avoid damage to the corrugated duct. During the construction, pay attention to avoid sharp objects such as iron parts to avoid scratches; When pouring concrete, try to avoid contact between the vibrating rod and the corrugated duct.