Greater levels of maximum fatigue loads and impressed current tended to shorten fatigue life.
When the maximum fatigue load is greater than 30% of the ultimate tensile loads, the chloride penetration is substantially accelerated.
Two distinctive failure modes were observed; (a) at maximum fatigue loads at and above 1500 N, the welds failed due to interfacial failure through the weld nugget and, (b) at maximum fatigue loads below 1500 N, the welds failed due to kinked crack growth through the top aluminum sheet.
The bar is assumed to abruptly break at failure when the localized fatigue stress ( sigma_{text{s,max}}^{text{f}} ) reaches the yield stress, as shown in Eq. (17): sigma_{text{s,max}}^{text{f}},ge, f_{text{yc}} (17 where ( sigma_{text{s,max}}^{text{f}} ) is the rebar stress corresponding to the maximum fatigue load at n cycles of repeated loading.
The other 12 specimens were tested under fatigue loading with load ratios ranging from 0.2 to 0.6 (defined as the ratio of the maximum fatigue load to the average static bond strength of control specimens).
Four different levels of maximum fatigue loads, namely 50%, 55 %, 65 and 75%and75%timate lofding capacity with fatigultimateng frequencies of 1.5 Hz and 4.5 Hz and corrosion impressed currents of 0.5 A, 1.0 A, 1.5 A and 2.5 A were apploading the beams.
The experimental results show that the tensile fatigue damage can accelerate the chloride penetration in concrete by 1.5 3.0 times, when the magnitude of maximum tensile fatigue load is between 25% and 45% of the ultimate tensile load of the specimen.
The ratio of minimum to maximum stress during fatigue loading (R-ratio) has been shown to influence subsequent tearing resistance, with an R-ratio of 0.2 generally leading to a greater enhancement in tearing resistance than an R-ratio of 0.1.
This research develops a method to predict the optimum re-peening time for maximum fatigue life under realistic loading conditions.
A total of 60 prism specimens were tested under fatigue loading considering maximum stress levels ranging from 90% to 60% of the static strength.
