Calculation method of stress loss in tensioning stage for prestressing tendons of space curve(PDF)
长安大学学报（自然科学版）[ISSN:1006-6977/CN:61-1281/TN]
- Issue:
- 2016年05期
- Page:
- 45-51
- Research Field:
- 桥梁与隧道工程
- Publishing date:
Info
- Title:
- Calculation method of stress loss in tensioning stage for prestressing tendons of space curve
- Author(s):
- ZHANG Shan-wen; WANG Xiu-xin
- Key Laboratory of C&PC Structure of Ministry of Education, Southeast University, Nanjing 210096, Jiangsu, China
- Keywords:
- bridge engineering; prestressed concrete engineering; prestressing tendon; space curve segment; tensioning stage; prestress loss; fixed point in theory
- PACS:
- U448.35
- DOI:
- -
- Abstract:
- Aimed at the calculation of prestress loss of prestressing tendons with space curve layout in prestressed concrete structure, based on the friction principle and space differential geometry relationship, formulas were derived to be used to calculate the stress loss in tensioning stage. For the two commonly used space curves of circular arc on a cylindrical surface and double parabolas in the projection planes in prestressing engineering, the practical formulas were given to calculate the space bending angle φ and space curve length s. In view of the situation of asymmetrical arrangement of tendons when tensioning was imposed on both ends, the calculating expression was also obtained to determine the fixed point (the stress balance point) in theory in prestressing tendons. The results show that in the given engineering example, the value of curve length from the beginning point of calculation to the fixed point in theory is 23.554 m by formulas method, and 23.520 m by finite element method. The difference between the two results is 0.15%. The value of effective prestress at the fixed point in theory is 868.48 MPa by formulas method, and 912.28 MPa by finite element method, The difference between the two results is 4.8%. The reasons for the error include the rounding error accumulation in data processing in each section by the formula method, the slight difference between the real space curve and that into the MIDAS Civil software and the density difference of beam element division in modeling. The loss of prestress, the values of efficient prestress and curve length can be conveniently obtained by the proposed formulas, and the calculation values are reliable, which means that the formula method is universal and practical.
Last Update: 2016-10-06