This article briefly introduces the ulter-long vertical prestressing techniques of the tube structure of the height of 350m above the ground,one of the key construction techniques under the engineering for Shanghai TV Broadcasting Tower,which is the third highest in the world.

Study on the vertical prestress loss of the prestress concrete box girder bridge web;

Test of vertical prestress loss and analysis research on it;

The vertical prestress applied to webs of concrete box girder is studied.

In this paper,starting from analysis of the sensitivity of slant box beam web cracks to vertical pre-stress,the dynamic mechanism of the effective reduction in main web pulling stress by vertical pre-stress is explained.

The distribution of ring pre-stress, anchoring steel beam and pre-stress, vertical pre-stress of the anchoring zone of the main tower in Songhuajiang cable stayed bridge are introduced and the corresponding construction technologies are clarified in the paper.

The vertical pre-stressed reinforcement installed in the pre-stressed concrete continuous (rigid frame) box beam bridge is to decrease and control the main tension stress of the web and to prevent the creaking.

Based on the long-term field measurement of vertical prestress losses in the box girder of a long-span PC continuous bridge,a detailed analysis of the loss of the vertical prestressing is conducted.

According to existing norms,the ratio of the vertical prestress loss to different length of the vertical prestressing bars is analyzed.