I. Prestressed tensioning operation

1. The tensioning operation of concrete prestressed steel bars should be performed only when the concrete age is reached or the concrete strength reaches 90% of the design strength and the concrete age is not less than 7 days;

2. The tensile control stress of the pre-stressed steel bar should be based on the design requirements and construction requirements, and the single-end single-branch tension is used for the tension;

Construction method of prestressed steel rod anchor

3. The tensioning sequence of the prestressed steel bars should be symmetrically stretched, that is, each block is symmetrically stretched, and each group of steel bars is stretched symmetrically (firstly, the middle and then both sides)

4. The "double control" control shall be adopted for the prestressing of the prestressed steel bar. The tension control is mainly used to check the elongation value. The tensile method is 0-10% σcon-100% σcon when tensioning. The error between the measured elongation and the theoretical elongation of the prestressed steel bar after tensioning is within ± 6%.

Construction method of prestressed steel rod anchor

Construction method of prestressed steel rod anchor

Tensioning construction steps

1. Tensioning process: clean the tension anchor hole → clean the end thread of the steel rod → install the tension rod → install the hexagonal sleeve → place the tension bracket to the correct position → install the jack → install the bottom lock of the jack → add the pump The load starts to tension → the chain pliers drive the hexagonal sleeve to lock the anchor nut → remove the load and return the oil to the jack → remove the jack → repeat the steps of other steel rods to tension

Construction method of prestressed steel rod anchor

2. Specific operation steps:

a. Before anchoring, first clean up the anchor hole, so that the exposed surface of the anchor pad is flat and clean;

b. Secondly, clean the external leakage thread at the end of the prestressed steel rod, so that the thread is free of debris or concrete residue;

c. The tension rod is connected to the tension head, the assembly is threaded to the end of the steel rod, and the connection length is not less than 30mm;

Construction method of prestressed steel rod anchor

d. The hexagonal sleeve is penetrated from the top of the tension rod, so that the hexagonal sleeve is engaged with the anchor nut;

e. Place the tension bracket so that the tension rod can pass through the center hole of the panel of the tension bracket to facilitate the installation of the jack. The tension bracket should be placed reliably;

f. Install a jack and install a lock nut on the tension rod to fix the jack;

Construction method of prestressed steel rod anchor

g. Turn on the oil pump and load it to the design force value, and use the locking chain pliers to drive the hexagonal sleeve to lock the anchor nut;

h. Remove the load, reset the oil return of the jack, remove the tensioning tools one by one, and perform the tensioning operation of other steel bars according to the same steps.