外文翻譯--平衡懸臂施工混凝土橋撓度和溫度的自動(dòng)監(jiān)測(cè)（英文）

1、AUTOMATIC DEFLECTION AND TEMPERATURE MONITORING OF A BALANCED CANTILEVER CONCRETE BRIDGE by Olivier BURDET, Ph. D. Swiss Federal Institute of Technology, Lausanne, Switzerland Institute of Reinforced and Prestressed C

2、oncrete SUMMARY There is a need for reliable monitoring systems to follow the evolution of the behavior of structures over time. Deflections and rotations are values that reflect the overall structure behavior. This pape

3、r presents an innovative approach to the measurement of long-term deformations of bridges by use of inclinometers. High precision electronic inclinometers can be used to follow effectively long-term rotations without dis

4、ruption of the traffic. In addition to their accuracy, these instruments have proven to be sufficiently stable over time and reliable for field conditions. The Mentue bridges are twin 565 m long box-girder post-tensione

5、d concrete highway bridges under construction in Switzerland. The bridges are built by the balanced cantilever method over a deep valley. The piers are 100 m high and the main span is 150 m. A centralized data acquisitio

6、n system was installed in one bridge during its construction in 1997. Every minute, the system records the rotation and temperature at a number of measuring points. The simultaneous measurement of rotations and concrete

7、temperature at several locations gives a clear idea of the movements induced by thermal conditions. The system will be used in combination with a hydrostatic leveling setup to follow the long-term behavior of the bridge.

8、 Preliminary results show that the system performs reliably and that the accuracy of the sensors is excellent. Comparison of the evolution of rotations and temperature indicate that the structure responds to changes in a

9、ir temperature rather quickly. measurements early in the morning and at the same period every year, it took a relatively long time before it was realized that the retrofit performed on the Lutrive bridges in 1988 by addi

10、tional post-tensioning [3, 7,11] had not had the same effect on both of them. -180-160-140-120-100-80-60-40June-79 June-82 June-85 June-88 June-91 June-94 June-97Vertical displacement since July 1973 [mm]Lausanne VeveyH

11、inge 1Hinge 2-20-100[mm]12:00 24:00 12:0018-19 May 89Hinge 1 NorthHinge 1 South(a) Evolution of deflections since 1973(b) Deflections over 24 hoursAdditional post-tensioningFigure 1: Long-term deflections of the Lutrive

12、bridges, compared to deflections measured in a 24-hour period Automatic data acquisition, allowing frequent measurements to be performed at an acceptable cost, is thus highly desirable. A study of possible solutions incl

13、uding laser-based leveling, fiber optics sensors and GPS-positioning was performed, with the conclusion that, provided that their long-term stability can be demonstrated, current types of electronic inclinometers are sui

14、table for automatic measurements of rotations in existing bridges [8]. 3. MENTUE BRIDGES The Mentue bridges are twin box-girder bridges that will carry the future A1 motorway from Lausanne to Bern. Each bridge, similar i