Risk-Based Life-cycle Assessment of Fatigue-prone Structural Systems considering impacts of Epistemic Uncertainties: economy, safety, and reduction of carbon emissions in the built environment

• Grant number: 25/00571-5
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: July 01, 2025
• End date: June 30, 2028
• Field of knowledge: Engineering - Civil Engineering - Structural Engineering
• Principal Investigator: André Teófilo Beck
• Grantee: Nophi Ian Delos Reyes Biton
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

Fatigue is responsible for 50 to 90% of all structural failures, with significant impact on operation, inspection, maintenance and failure costs. In complex structural systems, fatigue failure is managed by way of safety margins, redundancy and Inspection and Maintenance (I&M) operations. The later are costly and subject to error, as existing fatigue cracks may be difficult to identify. Redundancy prevents structural systems from collapse, due to fatigue failure of a single element, but it is also costly and adds complexity to the system. Redundancy also contributes to system robustness under unexpected loading cases, unexpected failure modes, and other epistemic uncertainties. Conventional Structural Reliability (SR) theory states that (gross) errors in design, construction, operation, I&M of structural systems should be handled by Quality Control, which includes I&M. Yet, Quality Control is not flawless; hence, some (gross) errors still pass, with significant impact on structural safety. Challenging conventional SR theory, the authors have recently shown that optimal system redundancy and optimal inspection strategies are dependent variables. Hence, the design of structural systems prone to fatigue, and the inspection and maintenance strategies, should be addressed simultaneously, using risk-based life-cycle optimization formulations. In the later, costs of materials, manufacturing, I&M, and the expected costs of failure are computed; the optimal solution is that which minimizes total expected costs, or which minimizes emission of greenhouse gases over the lifecycle of the structure. Yet, such solutions are highly susceptible to uncertainties of epistemic nature, which can be addressed by the author´s Latent Failure probability concept. This project will address the optimal lifecycle design of structures like offshore platforms subject to wave loading, and steel buildings subject to low-cycle fatigue under extreme wind loading. (AU)