Behavior of completely overlapped tubular joints under cyclic loading

The completely overlapped joints of the eccentrically braced offshore jacke ts were investigated both experimentally and numerically. A full-scale spec imen was tested under cyclic quasi-static loading. In the test, local buckl ing was first observed around the lap brace and through-brace intersection. A crack was then developed at the weld toe between the lap brace and the t hrough brace, and the propagation of the crack led to the final failure of the joint. Indicators to assess the performance of the joints were evaluate d within the context of seismic resistance. The energy analysis indicated t hat the local buckling at the intersection area was the main energy-dissipa ting mechanism. A comparison with an N-joint showed that the completely ove rlapped joint performed better under seismic loadings. An extensive finite- element analysis showed that increasing the lap brace diameter could improv e the hysteresis performance of the joint while changing the gap size and t he wall thickness of the through brace would have limited effects.