Issue 30

A. Fernàndez-Canteli et alii, Frattura ed Integrità Strutturale, 30 (2014) 327-339; DOI: 10.3221/IGF-ESIS.30.40 330 was derived from a loading collective, consisting in 30 steps of the maximum normalized stress S max =  max/  R . After truncation at level 18 and omission of stress ranges below level 9, which implies to discard the lower stress levels, presumably without causing damage, the definitive stress collective in Fig. 3b, considered as representative of the effective stress being supported by the concrete in the real off-shore structure, was applied to the specimens in a pseudo-random sequence. a) b) Figure 3: Holmen’s load collectives from [4]: a) Original load histogram consisting in 30 stress steps and b) Loading model 3 with truncation of higher stress amplitudes and omission of lower stress amplitudes applied in the fatigue variable testing . In order to reduce as much as possible the influence of the sequence, a proportional fraction of the number of cycles represented in the histogram, the so called “basic loading block”, will repeatedly applied until failure. The smaller the length of the basic loading block, the closer the random nature of real load applied, and the better the agreement between the total number of cycles applied during the test and its correspondence to the different stress ranges intervening in the load collective for the purpose of the Miner number calculation. An improvement of the real sequence could be achieved