|Table of Contents|

Fatigue assessment of rectangular hollow section K-joints due to degree of bending(PDF)

《建筑科学与工程学报》[ISSN:1673-2049/CN:61-1442/TU]

Issue:
2023年05期
Page:
119-128
Research Field:
建筑结构
Publishing date:

Info

Title:
Fatigue assessment of rectangular hollow section K-joints due to degree of bending
Author(s):
ZHAO Rui1;  LIU Yongjian2; 3;  JIANG Lei2; 3;  FU Yisheng2;  ZHAO Yadong2;  ZHAO Xindong2
(1. Department of Bridge Engineering, Tongji University, Shanghai 200092, China; 2. School of Highway, Chang'an University, Xi'an 710064, Shaanxi, China; 3. Research Center of Highway Large Structure Engineering on Safety of Ministry of Education, Chang'an University, Xi'an 710064, Shaanxi, China)
Keywords:
fatigue assessment;  rectangular hollow section K-joint;  degree of bending;  fracture mechanics method
PACS:
U441.4
DOI:
10.19815/j.jace.2022.01040
Abstract:
In order to improve the accuracy of fatigue assessment methods such as S-N curve method and fracture mechanics method, the calculation method of degree of bending(DoB)of rectangular hollow section(RHS)K-joints under tension-compression balanced axial force was discussed. Firstly, the finite element model of RHS K-joints was established and verified by experiments. Then, the influence of joint geometric parameters on the DoB was obtained through a large number of parameter analysis. Finally, the calculation formula of the DoB and the correction formula considering the partial safety of engineering by multivariate nonlinear regression analysis. An example of fracture evaluation of RHS K-joints based on fracture mechanics method was given. The results show that compared with the experimental values, the average bending stress ratio of the established model is 1.051, the mean square error is 0.167, and the maximum difference between the two is only 7.5%, indicating that the established finite element model is reliable. Compared with the finite element calculation results, the mean value of the proposed DoB calculation formula is 1.073, the mean square error is 0.055, the coefficient of variation is 0.051, and the relative difference is within 10%, which verifies the reliability of the fitting formula. Considering the partial safety application of practical engineering, the formula for calculating the DoB is modified by multiplying the safety factor by 0.93 times under the guarantee rate of 99.73%. When the hot spot stress is similar, DoB is reduced by 39.3%, and the fatigue life will be reduced by 10%. When the membrane stress becomes larger, and the crack tip will have a larger stress intensity factor and accelerate the crack propagation rate.

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Last Update: 2023-09-01