|Table of Contents|

Tension identification principle and technology for prestressing finerolling screwthread steel bars based on a threaded connection model(PDF)

长安大学学报（自然科学版）[ISSN:1006-6977/CN:61-1281/TN]

Issue:
2019年04期
Page:
82-91
Research Field:
道路工程
Publishing date:

Info

Title:
Tension identification principle and technology for prestressing finerolling screwthread steel bars based on a threaded connection model
Author(s):
ZHONG Xingu;  ZHANG Tianyu;  PENG Xiong;  SHU Xiaojuan;  SHEN Mingyan
（Key Laboratory of Windresistant and Vibration Control for Structure of Hunan Province, Hunan University of Science and Technology, Xiangtan 411201, Hunan, China）
Keywords:
bridge engineering;  tension identification;  natural frequency identification;  finerolling screwthread steel bar;  spring connection;  contact stiffness
PACS:
-
DOI:
-
Abstract:
To prevent web cracking of a pretensioned concrete box girder bridge, this study aimed to provide a more efficient accurate test technique for effective tensile force of prestressing finerolling screwthread steel bars and revised the relevant regulations. It was considered that the anchorage nut and the anchor plate of prestressing finerolling screwthread steel bars were connected by springs and the stiffness of the coupling spring was the normal contact stiffness of the contact surface. Dismissing the fixation assumption of the steel bars and anchorage nut, the connection between the steel bar and nut threads were considered as a cantilever structure and the stiffness of springs was calculated using the graphic multiplication method. The dynamic model of the bending vibration of the prestressing finerolling screwthread steel bars was established. During the process of joint force transmission of finerolling screwthread steel bars, the force transmission in each lap of thread was nonuniform, and the farther away from the contact surface, the smaller the force transmission. This may change the length of the exposed segment of the steel bars and affect the accuracy of the test results. Based on the thread characteristics, a modified equation of the normal contact stiffness of the contact surface was proposed. Finally, model tests and field tests of multiple bridges were conducted. The results show that the problem of the tension test error caused by the different exposed segment lengths of the anchor system of the prestressing finerolling screwthread steel bars is solved using this method. The relationship between the normal contact stiffness and tension of the anchorage nut and anchor plate is obtained and which conforms to the general rule of the relationship between the normal contact stiffness and force. The results of the model and field tests show that the relationship between the normal contact stiffness and tension is stable and effective and can be used to conduct field tests and revise the current test specifications. The implementation of this code is of great significance to thoroughly solve the problem of excessive loss and failure of vertical prestress. It can be extended to other structures with a similar anchorage system. 6 tabs, 11 figs, 21 refs.

References:

Memo

Memo:
-
Last Update: 2019-07-29