組合せ荷重を受けるパイプの最終強度(その1) : 曲げ,外圧および軸力を受ける海底パイプラインの崩壊強度解析

概要

論文の詳細を見る
Submarine pipelines which transport oil and gas are now being installed or planed for more and more deep waters. It was reported that planed crossing includes a Norweigian Trench crossing with depth to 350 m and trans-Mediterranean crossing with depth to 2,OOO m. Submarine pipelines to be installed at such depths will require the utmost care in engineering design. During a pipelaying operation, the pipe is subjected to the combined loads of bending, tension and external pressure. Considering the fact that bending stress during installation often reach the yield range, even though DNV Rules allow 0.2% residual longitudinal strain, it implies that this bending may become a collapse initiator. Furthermore, it should be considered that initial deformation reduce the resistance of pipeline against collapse, especially in deep water. A rigorous analytical treatment of the collapse strength of pipeline during installation is very complicated, because it is a function of loading conditions as well as D/t ratios, material properties, arid initial deformation. In this paper a simplified analytical method, which was proposed by authors for evaluating the ultimate strength of stiffend plate, is extended in order to estimate the collapse strength of pipeline under the action of combined bending, axial force and external pressure, including the effect of initial out-of-roundness. The present method is compound of two parts. One is elastic analysis based on energy method, and the other is plastic analysis in which collapse mechanism is assumed. In both analysis large deformation is considerd. The following conclusions are obtained. 1) Theoretical results are checked with available published data. It is confirmed that this proposed method is fairly efficient one. 2) Since this proposed method is an analytical one that the complicated collapse strength of a pipe with out-of-roundness under combined loads can easily be estimated comparing with other numerical methods. 3) Analytical results indicate that there exist two different collapse modes for pipelines under combined bending and external pressure. One of them is circumferential flattening of pipe cross section (circumferential collapse) and the other is so-called Brazier's type of failure (bending collapse). 4) Analytical results show that both bending moment and axial tension considerably reduce the external pressure-bearing capacity.
社団法人日本船舶海洋工学会の論文

組合せ荷重を受けるパイプの最終強度(その1) : 曲げ,外圧および軸力を受ける海底パイプラインの崩壊強度解析

スポンサーリンク

概要

著者

関連論文

スポンサーリンク