What are the main characteristics of the jacking construction method of steel box girder?

First, jack-up construction methods can be divided into single-point jack-up and multi-point jack-up. Incremental launching method is mostly used in the construction of prestressed reinforced concrete continuous beam bridges and cable-stayed bridges. It refers to the construction method that the beam body is poured or assembled section by section at the bridge head, and pushed longitudinally with a jack, so that the beam body is in place through the temporary sliding bearing surface at the top of each pier.

Second, the jacking construction is to set up a construction site behind the abutment, pour the beam in sections, connect the pouring section with the completed beam with longitudinal prestressed tendons, install a steel guide beam with a length of about 0.7 times of the jacking span in front of the beam, and then push the beam out of the construction site with a horizontal jack. Repeat these procedures to complete the construction of all beams.

3. 1959 incremental launching method is adopted for the first time in Austrian Agel Bridge. It is characterized in that because the workplace is limited to a certain range, a ceiling can be set above the workplace, so that the construction is not affected by the weather and can be carried out all day. The jacking span of continuous beam is 30~50m, which is the most economical and advantageous. If the span is greater than this value, auxiliary means such as temporary pier support are needed. The continuous prestressed concrete beam bridge with equal cross-section should be constructed step by step, and the composite beam and girder of cable-stayed bridge can also be constructed step by step. Incremental launching method has the advantages of simple equipment, stable construction, low noise and good construction quality, and can be used for bridges, viaducts, curved bridges with equal curvature, curved bridges and skew bridges over deep valleys and wide rivers.