Multi-objective optimization of structural fire design

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.

概率风险评估可用于确定具有在合理可行的范围内尽可能低（ALARP）的剩余风险的设计。然而，现有的基于风险的设计方法主要侧重于单一目标，考虑到结构需要在多个维度（包括货币成本、环境成本和结构性能指标）满足不同的性能标准，这可能是不切实际的。为了应对这些挑战，本研究提出在基于风险的框架内使用多目标优化（MOO）方法。在MOO框架内，可持续性和韧性的设计目标与安全目标一起被纳入。此处针对暴露于火灾的结构的基于风险的设计开发了MOO方法。通过确定设计参数、目标和约束条件，为多户住宅中的钢筋混凝土板制定了一个多目标问题。在案例研究中，考虑环境成本对通过MOO获得的最优设计影响很小，除非二氧化碳排放被高度重视。观察到投资有限增加可使结构在火灾事故后可修复，这凸显了在结构防火设计中考虑火灾后可修复性的重要性。