Marine infrastructure rejuvenation engineering fatigue and fracture of critical structural details (CSD).

摘要

Infrastructure Rejuvenation Engineering (IRE) is the retrofit, renewal, reconstruction, and rehabilitation of our deteriorating infrastructure. This infrastructure is mostly public-owned structures, installations, and networks that convey and connect people, water, goods, energy, and information.; Fatigue and fracture of Critical Structural Details (CSD) constitutes one of the major maintenance issues for existing infrastructures. This dissertation addresses fatigue and fracture problems in IRE. Fatigue and fracture of ship CSD is the primary focus of this work.; In this dissertation, a general fatigue analysis procedure is developed and updated. The Stress range-Number of cycles to failure (SN) model is applied in the fatigue design and assessment of CSD where the nominal stress approach and the hotspot stress approach are employed. The Fracture Mechanics (FM) modeling is developed and applied to the in-service assessment of cracked CSD. This FM model is further simplified based on a 'cracked SN curve' approach. The FM (linear and nonlinear) and Failure Assessment Diagram (FAD) are used to determine the final fracture of CSD. These models are further developed in the probabilistic sense to account for the uncertainties in the fatigue analysis procedure. Special contributions to IRE have been made by this research in the following areas: (1) The proper fatigue stress and corresponding SN curves for large CSD, (2) Mean stress effects in the SN approach, (3) Fracture mechanics modeling of large CSD, (4) Hybrid SN-FM methodology and cracked S-N Curves, (5) Redistribution of stress in cracked CSD and interaction with adjacent members, (6) Final fracture and critical crack size for large CSD, (7) Long-term fatigue loading process and its distribution, (8) Sensitivity and uncertainty of fatigue reliability models, and (9) Fatigue updating procedure and fracture reliability.; These technical developments can be extended directly for general CSD in infrastructure systems to provide physical mechanisms and engineering tools for evaluation of fatigue and fracture in infrastructure rejuvenation.