Multi-objective optimization of structural fire design

Abstract

Probabilistic risk assessment can be used for determining a design with a residual risk that is As Low As Reasonably Practicable (ALARP). Existing risk-based design approaches however predominantly focus on single objectives, which can be impractical considering the need for structures to meet diverse performance criteria across various dimensions, including monetary costs, environmental costs, and structural performance measures. To address these challenges, this study proposes the use of a multi-objective optimization (MOO) approach within a risk-based framework. Within the MOO framework, design goals for sustainability and resilience are incorporated together with safety objectives. The MOO approach is developed here for the risk-based design of structures exposed to fire. A multi-objective problem is formulated for a reinforced concrete slab in a multi-family dwelling by identifying design parameters, objectives, and constraints. Taking environmental costs into account has little effect on the optimum design obtained through MOO for the case study, except in cases where CO2 emissions are highly valued. A limited increase in investment is observed to render the structure repairable after a fire incident, highlighting the importance of factoring in post-fire reparability in structural fire design.