Stress concentrations in simple tubular joints（应力集中在简单的管状接头）.pdfVIP

April 2009/ John Wægter Note 3.1 Stress concentrations in simple tubular joints Introduction2 Types of joints4 General4 Definitions and symbols 4 Stress concentration factors 6 Classification of simple joints10 General10 Influence from force flow 10 Tubular joints and members according to DNV-RP-C20312 Introduction12 Tubular joints (2.3.4) 12 Stress concentration factors for simple tubular joints (3.3.1) 12 Superposition of stresses in tubular joints (3.3.2)12 Tubular joints welded from one side (3.3.3)14 DNV Appendix B15 References25 1 Stress concentrations in simple tubular joints Introduction Typical offshore structures are composed of three dimensional frames fabricated from steel tubulars. The connections between the different tubular members are denoted tubular joints. A tubular joint is made up of a chord (element of largest diameter) and one or more braces. Figure 1 Tubular joints Both the structural members (elements) and the tubular joints must be designed to sustain the ultimate design load (e.g. the 100-year design condition), and the long term cyclic stresses due to environmental action. This lecture focuses on the fatigue aspect by demonstrating how the hot spot stress approach is used. The design process consists of a global analysis and a local analysis. The global analysis determines the sectional forces and the nominal (beam) stresses in the various elements of the structure. Figure 2 Global and local analysis 2 These sectional forces es