ABSTRACT
The early days of offshore construction were by trial and error, i.e. learning from failures. Early research from Texas – cowboy technology – found its way into AWS D1.1 in 1972, in the form of punching shear criteria for ultimate strength (Vp) and fatigue (Curves T&K). Hot spot stress was also introduced (Curve X), as well as fitness-for-purpose ultrasonic testing (class X). Further developments in ultimate strength include the collection of more extensive data bases, design visualization, and design by components. Punching shear also shows up in boundary tractions and mixed mode crack propagation. Further developments in fatigue include hotspot stress vs. fracture mechanics, hotspot stress vs. notch stress, non-tubular applications, marine hull calibrations, fatigue with shear at welds, and progressive tensile fracture. Tubular structures today can be as reliable as other structural types, and have been mainstreamed into design Codes, e.g. AISC (2005). However, there is no 20,000 cycle guarantee at full static allowable. Bigger and better offshore structures, and bridges at last, enter the scene. Recent standardization work includes: international criteria for materials, welding, inspection, fabrication, and quality1 , 2 (superscripts refer to the PPT file, available from mhpsyseng@aol.com).
