Prestressed steel strands are widely used in building construction because of their structural stability. However, if some wrong operations occur during the construction process, the prestressed concrete strands cannot be put into use well. The following is the construction process of prestressed concrete strands.
Cutting
The steel strand must be cut in a flat, water-free, and clean place. The length of the strand must be determined by calculation. The calculation should consider factors such as the length of the tunnel curve, the length of the anchor clamp, the length of the jack, and the exposed working length. Cut the material according to the length required by the design.
During the construction of the box girder with the first hole, cut 200mm longer than the length required by the design, and then adjust the cutting of the steel strand required for the subsequent box girder according to the construction of the box girder with the length of the first hole, allowable length error 10mm.
The prestressed tendons should be cut with a grinding wheel saw, and the cut ends of the steel strands should be fastened with iron wires during the cutting process, and cut with a grinding wheel cutting machine.
Bundle
When bundling, the steel strands must be parallel to each other and must not cross. From the middle to the two ends, tie them with iron wires every 1m, and number the steel strands.
After the bundling is finished, it is transported to the designated location, and the uniform number and tag are prepared, and they are stacked neatly according to the category for use. Do not drag directly during transportation to avoid damage and corrosion on the surface of the steel strand.
Threading
Before threading, check whether the pipeline is unblocked. If the channel is blocked, measures must be taken to clear it. The end of the steel strand must be made into a cone shape and wrapped, which can be pulled manually or by a hoist and bundled before pouring the concrete (the suspension cast box girder across the embankment is bundled after pouring).
When threading the bundle, insert a guide rope into the pipeline, use the guide rope to lead the steel wire, connect the other end of the steel wire with the steel bundle tractor, and use the hoist to pull the steel bundle out.
Tensioning
After the tensioning and beaming are completed, the tensioning is carried out in the order of two sides first and then the middle according to the design requirements. The prestress size control is based on the reading of the oil pressure gauge as the main reference basis, and the elongation value of the prestressed tendon is used as a review.
Lateral prestressed installation
The transverse prestressed concrete steel strand and corrugated pipe are installed after the longitudinal prestressed pipe is installed. Use manual threading, anchor one end of the steel strand with a tie anchor, and slowly pass the other end into the flat corrugated pipe.
We must strictly follow the construction standards to deal with the prestressed concrete strands so as not to damage its own structure. If you want to know more about prestressed concrete strands after reading the above content, you can get a comprehensive solution by contacting us.
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