Journal:CHINA JOURNAL OF HIGHWAY AND TRANSPORT

Key Words:bridge engineering lift-off test effective prestress under anchor temperature effect time effect Weibull distribution hypothesis test

Abstract:After a prestressed steel strand is tensioned, the effective prestress changes in accordance with time and temperature. To reveal accurately the variation law of effective prestress under anchors based on the influence of temperature and time, and to improve the test accuracy of lift-off test technology in practical engineering, an experimental study of time effect and temperature effects was conducted. When the steel strand was tensioned, a pressure sensor was placed under the anchor to perform real-time dynamic monitoring of the effective prestress and temperature of the steel strand in the precast beam with different spans and sections. Tests of 40 and 27 bundles in the long-term (1 month) and short-term (72 h), respectively, were used to analyze the effects of the temperature and time effects on the effective prestress changes under the anchor. Statistical analyses of several test results were performed. The results show that in the previous 500 h, an overall damping trend of the prestress occurs, and a similar sine wave change occurs during the entire test process. A similar sinusoidal wave change is caused by the temperature change. Compared with time effect, the effect of temperature on the effective prestress under anchors is less. After 500 h, the damping of the effective prestress decreases and the effective prestress is in a relatively stable state. Within 48 h, a discrepancy arises in the damping law of 67 steel strands without considering the effect of temperature. In addition, the discrepancy increases with time. The loss rate of each strand obeys the Weibull distribution within 48 h. The correction calculation formula can correct the lift-off test results affected by temperature and time in an actual bridge engineering test.

All the Authors:刘佳琪,高华睿,管钧

First Author:张峰

Indexed by:Journal paper

Correspondence Author:叶见曙

Discipline:Engineering

First-Level Discipline:Civil Engineering

Document Type:J

Volume:32

Issue:9

Page Number:80-89,114

Number of Words:7000

Translation or Not:no

Date of Publication:2019-06-01

Included Journals:EI