Pretensioned prestressing box girder strain and relaxation process

Abstract

The invention discloses a novel technology capable of tension and extension of a straight line rib and a crease line rib at the same time. The technical proposal lies in that after a pre-stress steel wire is lashed, a mode of synchronous classified tension of both ends is adopted, to first initially set a straight line rib, and then initially set and tension a crease line rib, and finally tension the straight line rib; a large ton hydraulic jack is adopted for overall classified extension and a spiral support is adopted to follow up and protect the extension process; the crease line rib is first extended, followed by the straight line rib. The invention selects the large ton jack, adopts the initial setting of the single pre-stress, classified overall tensioning of the jack, and follow-up and protection with a spiral support tensioning and extending technologies, which can prevent low efficiency and unsafety, etc brought by single tensioning, ensure balance stress on box beams and safety extension, improve the extending efficiency, and is applicable to tensioning and extending of pre-tensioning method pre-stress concrete box beams with the extending ton up to 52000Kn.

Description

technical field [0001] The invention relates to a tensioning and releasing process of a building component, more specifically to a tensioning and releasing process of a pretensioned prestressed box girder. Background technique [0002] my country began to study and trial-manufacture pre-tensioned beams in 1958, but in terms of reinforcement forms, linear reinforcement is mostly used. In terms of prestressing, one end is usually stretched, and the other end must be set with a fixing device or placed before tensioning. The relaxation device of the prestressed tendon also has a method of tensioning at both ends. In terms of tensioning process, single tensioning and multiple tensioning are used, but due to the small tensioning tonnage, the selected jack has a relatively small tonnage, a small stroke, and a small pressure on the oil circuit device. The protection and support of the jack during the tensioning process Iron pads are often used, which has low work efficiency; in term...

AI Technical Summary

Problems solved by technology

In terms of tensioning process, single tensioning and multiple tensioning are used, but due to the small tensioning tonnage, the selected jack has a relatively small tonnage, a small stroke, and a small pressure on the oil circuit device. The protection and support of the jack during the tensioning process Iron pads are often used, which has low work efficiency; in terms of prestress relaxation, the methods used include small-tonnage jacks first pulling and then loosening, sand box relaxation, sliding wedge relaxation and screw relaxation, etc. These prestress relaxation methods are not safe. Terminal synchronization is poor and efficiency is relatively low

However, there is no literature report on the tensioning and releasing process of the pre-tensioned prestressed concrete simply supported beam with a tonnage of 5200t using broken line reinforcement.

Images