الفهرس 
CoverOnly 14 pages are availabe for public view
 |  | from | 333 |  |  |
| | | from | 333 | | |
Abstract
Structural integrity is the science and technology of the margin between safety and disaster. Proper evaluation of the structural integrity and fatigue life of any structure (aircraft, ship, railways, bridges, gas and oil pipelines, etc.) is important to ensure public safety, environmental protection, and economic consideration. Catastrophic failure of any structure can be avoided if structural integrity is assessed and necessary precaution is taken appropriately.
Structural integrity includes tasks in many fields, such as structural analysis, failure analysis, nondestructive testing, corrosion, fatigue and creep analysis, metallurgy and materials, fracture mechanics, fatigue life assessment, welding metallurgy, development of repairing technologies, structural monitoring and instrumentation …. etc.
In this research as a part of integrity checks; fatigue life assessment for single side welded tubular joints of two fixed platforms is numerically assessed as part of mitigation for platform life time.
The platforms are four-leg piled fixed types located in Eastern and Southern blocks of the Gulf of Suez, Egypt. The platforms are installed in 33.5 and 85.0 meter water depth respectively.
The numerical fatigue assessment method is based on S-N curve approach for both API and DNV standards utilizing the Simplified where the Spectral (stochastic) method is based on the API; applying the static and dynamic stress range data extracted from the SACS software package, offshore engineering soft-ware, on the jacket joints to demonstrate the fluctuating cyclic environmental conditions for one year waves to ensure that the entire jacket can safely withstands without any sudden brittle failure.
This assessment is carried-out to investigate the effect of current, jacket natural period, and jacket stability on the fatigue life-time of the jacket tubular joints and check the minimum factor of safety achieved for each joint.
The result trends for these studies show that the effect of the current is about 10%; the static stress range is not influenced with the natural period of the jacket while the dynamic response of both the jacket and waves is significant wherever the jacket natural period exceeds the 3 seconds. The behavior of the jacket improves towards stability maintained from geometry of the Rows batter (vertical or inclined jacket faces) leading to improve the life-time of the joints with an average of 13% despite increasing natural period of the platform from vertical to inclined face as result of applied loads from members’ self-weight .
Through this fatigue assessment for the jacket tubular joints, studies are carried-out for the stress concentration factor (SCF) parametric equations of Efthymiou and Lloyd’s to define the upper and lower numeric boundaries for axial, in-plane and out-of-plan bending based on the international codes geometric limitations for simple tubular joints of types (T-Y, X & K) where the results are presented in trend tables and charts.