Economic impact of performance-based fire design of composite steel frame structures

Abstract

Adopting a performance-based design approach can often result in superior technical solutions for structural fire safety, for example increasing structural resilience, but the economic implications remain poorly understood. Prescriptive fire designs are still the default method, despite advances in structural fire engineering showing the potential to deliver higher levels of performance and/or more efficient designs. Here we evaluate the lifetime costs of various fire designs for composite steel-concrete structures considering investments, co-benefits, and averted fire-induced losses. The proposed method integrates construction and maintenance costs, potential direct and indirect damage losses from fire incidents, co-benefits such as compressed construction schedule, and lifetime CO₂ emissions. We study multi-story residential buildings with four variations of structural fire designs for the composite floor systems. The performance-based design, which leverages membrane action in the floor, is generally more cost-effective than the prescriptive design, owing to its lower probability of integrity failure and lower amount of fire protection material. The superiority of the performance-based design becomes more pronounced as material and labor costs increase, and as indirect losses from building closures grow. The fire load influences the relative cost-effectiveness of the designs through the expected fire severity, so optimum designs can be identified as a function of statistical fire load models based on occupancy. These findings can support decision-making and code advancements by providing economic data that complement previous technical studies on the merits of the performance-based design approach for structural fire design.