PSI - Issue 13

Mihaela Iordachescu et al. / Procedia Structural Integrity 13 (2018) 584–589 M. Iordachescu, M. de Abreu, A. Valiente/ Structural Integrity Procedia 00 (2018) 000 – 000

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The second testing method used in the present research, namely the fatigue test under transverse loading (here referred as F-QL), was designed to reproduce the fatigue behaviour of the wires when simultaneously subjected to cyclic tensile loading and static compressive transverse loading. The same test arrangement given in Fig. 1 was employed, with the only difference being given by the cyclic nature of the tensile load by applying the stress rage of 200 MPa, recommended by the International Federation for Structural Concrete, FIB (2005) for fatigue testing of prestressing wires. The tests were performed for different combinations of the maximum tensile fatigue load and the transverse load P Fmax – Q. According to (FIB, 2005), with the tests not exhibiting in fatigue failure before 2∙10 6 load cycles were considered as resulting in infinite fatigue life; although most of tests were continued up to 5∙10 6 load cycles. Lastly, macro-microscopic analyses of the fracture surfaces were performed in order to identify the fracture features and the corresponding damage mechanisms of wires when subjected to T-QL and F-QL tests.

Fig. 2. Tensile load vs. percentage elongation dependency on constant transverse compression loads Q, of: a) LDS; b) DSS; c) ES wire specimens

Fig. 3. a) Macroscopic fracture features of the LDS wire specimens when subjected to axial tensioning and transverse loading; b) Experimental tensile bearing capacity of the wires vs. transverse load