FATIGUE OF CFRP STRENGTHENED STEEL CONNECTIONS UNDER COMBINED ACTIONS

摘要

In this paper a series of experiments was performed to investigate the effectiveness of composites on preventing fatigue crack propagation and extending the fatigue life of steel connections under combined loads, including a cyclic mode I load and a tensile static load. Each specimen is formed by two steel plates joined together by single-sided girth welds. To prevent premature failure, an initial notch was machined. The steel connections were reinforced with single-sided CFRP sheets. Different numbers of CFRP overlays were applied. All the specimens were tested to failure under a constant amplitude tensile cyclic load combined with varied tensile static load, which are perpendicular to the cyclic load. The experimental results reveal that the presence of tensile static load is able to reduce the fatigue crack growth rate and hence results in a longer fatigue life. This observation is true for the steel connections with and without CFRP overlays. The effect of tensile static load on the number of fatigue cycles at varied layers of CFRP sheets was evaluated by the comparison of their fatigue lives.