Structural Behavior of Dented Tubular Members Under Lateral Loads

Structural behavior of tubular members with dent damaged caused by local indentation remains a key issue for the safety and failure assessment of critical structures, including marine facilities, oil and gas pipelines. This failure mode most often arises from very large localized plastic deformations caused mainly by excessive or accidental loads such as, for example, during the collision of adjacent risers in deepwater floating production systems (FPS). The complex interaction between the local deformation in the dented region and global bending of the tubular member may severely reduce the plastic collapse load which strongly affects its load-deflection behavior. This study presents an experimental and numerical investigation of the structural behavior of a dented tubular member under lateral load which is applicable to marine risers. Experimental load-deflection curves measured using a $412″O.D.$ (114 mm) API N80 pipe (580 MPa yield stress) with varying length characterize the plastic response during local indentation and global bending. 3D finite element models are employed to generate numerical solutions describing the large deformation, non-linear behavior for the tested pipes. The experimental results agree well with the numerical results. The analyses provide further insight into the structural response of tubular members and risers with dent damage effects.