RESIDUAL STRESS ANALYSIS AND FATIGUE ASSESSMENT OF WELDED STEEL STRUCTURES

Abstract

The S-N curves with their related fatigue classes are used for fatigue design and analysis on steel and composite bridge structures utilizing nominal stress approach. It's possible that this approach will overestimate the impact of loads on structural components because there are so many different structural elements and loading scenarios to consider these days. When the nominal stress can't be simulated due to geometry or loading complexity, or when there isn't a classified detail to compare it to design codes, hot spot was established to properly assess the influence of loads on the fatigue strength of welded steel structures. The benefits of this method's long history of use in fatigue design and analysis are yet to be realized by steel and composite structures. The study utilizes finite element approach for calculation of design stresses, for fatigue life estimation. First of all a comparative experimental study is done between global and local stresses so as to give insight why local approach would be beneficial. Thereafter using different weld modelling techniques a finite element analysis for local life assessment methods such as hot spot stress approach, for complex steel structure is performed to verify its applicability. From the experimental comparative study, the variation between the results of global and local life assessment methods was not very much which was unexpected, but still the results showed that the local stress life assessment approach was more suitable for study. For FEA solid weld models yielded more realistic results, but some discrepancy was found in hot spot 2 which needed further investigation.