High-strength steel tubular welded joints under extreme loading conditions

Abstract

The present work examines the behavior of high-strength steel welded tubular connections subjected to extreme loading conditions, focusing on their monotonic and low-cycle fatigue performance. The work consists of two parts. An experimental investigation of the highstrength steel tubular X-joints behavior under monotonic and cyclic loading levels exceeding the elastic limit is presented first. The second part of the work is numerical aimed at supporting the experimental results through finite element modeling and extending the investigation on other geometrical configurations not covered experimentally. Emphasis is given on the low-cycle fatigue performance of the joints based on the "hot-spot" results. For each test the overall joint behavior and local phenomena at the weld toe are simulated and the numerical results are compared with the present experimental measurements and those found in the literature. Special attention is given on the evaluation of stress and strain fields at the joint "hot-spot" locations. The currently available strength and fatigue design methodologies are presented and compared against the experimental results. This research effort is aimed at proposing static and low-cycle fatigue design methodologies for welded tubular connections made of high-strength steel. © Copyright 2016 by the International Society of Offshore and Polar Engineers (ISOPE).