Ezperimental determination of stress intensity factors on large-scale tubular trusses
The fatigue design of tubular space trusses for bridge applications requires additional knowledge with respect to their fatigue resistance. In order to be able to model thoroughfully the fatigue crack initiation and propagation phases, it is important to have at disposal as much as possible information on crack development. The paper presents the results of crack depth measurements using an Alternate Current Potential Drop (ACPD)system. The originality is that the system was installed on the nodes of two truss specimens, 9m by 2m, with K-joints made out of CHS. This system has, to our knowledge, never been applied to large-scale specimens such as those. The multiple electrical current passes possibilities made it difficult to predict if the system would actually measure correctly. The paper describes the tests carried out and the equipment installed. A total ofeight probes where installed at the most likely crack locations. The results obtained from the tests are givenin terms of S-N data, of crack depth versus number of cycles, of crack propagation rate and of stress intensityfactor range, obtained using the Paris law with constants calibrated on previous tests on similar elements.Comparisons with opened crack surface after testing show good agreement with crack depth deduced fromACPD measurements. The paper also contains plots with both crack propagation from numerical calculations and deduced from measurements, which show similar features. Finally, for the test conditions used in this study and from the ACPD measurements, it can be concluded that crack propagation starts early and thus that the crack initiation period is small. This is an important result for proper modelling of the fatigue behavior in this type of tubular joints.
A.Nussbaumer L.Borges
Swiss Federal Institute of Technology Lausanne, ICOM-Steel Structures Laboratory, Lausanne, Switzerland
国际会议
第12届钢管结构国际学术会议(The 12th International Symposium on Tubular Structures)
上海
英文
351-358
2008-10-08（万方平台首次上网日期，不代表论文的发表时间）