What are the main technical requirements for the construction of concrete filled steel tube?

1. The concrete in the steel pipe should adopt the pumping jacking and pressure injection and construction, and it should be completed by a symmetrical and balanced pressure injection from two arches to the vault.

2. Long-span arch-ribbed steel pipe / construction engineering education network / concrete shall be designed according to the design loading procedure, and it should be divided into rings, sections and compartments symmetrically and pressure-injected symmetrically from the arch foot to the vault. The displacement of arch ribs during the injection process must not exceed the design requirements.

3, concrete-filled steel tube should have low foam, large fluidity, shrinkage compensation, delay the initial setting and early performance.

4. Before the injection of steel pipe concrete, the dirt in the pipe shall be cleaned, and the wall of the pipe shall be wetted. The appropriate amount of cement slurry shall be pumped before the concrete shall be pressed and injected until the exhaust pipe of the top of the steel pipe discharges the qualified concrete. After the injection of concrete is completed, the reverse flow stop valve should be closed.

5. The method for quality inspection of concrete filled steel tubes should be based on ultrasonic testing, supplemented by manual percussion testing.

6. The pumping sequence of concrete-filled steel tubes should be carried out according to design requirements.