Behavior of Completely Overlapped Tubular Joints under Cyclic Loading

Abstract

The completely overlapped joints of the eccentrically braced offshore jackets were investigated both experimentally and numerically. A full-scale specimen was tested under cyclic quasi-static loading. In the test, local buckling 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 through brace, and the propagation of the crack led to the final failure of the joint. Indicators to assess the performance of the joints were evaluated within the context of seismic resistance. The energy analysis indicated that the local buckling at the intersection area was the main energy-dissipating mechanism. A comparison with an N-joint showed that the completely overlapped joint performed better under seismic loadings. An extensive finite-element analysis showed that increasing the lap brace diameter could improve the hysteresis performance of the joint while changing the gap size and the wall thickness of the through brace would have limited effects.