A comparison between prescriptive- and performance-based approaches in fire safety design of structures

A provision of an adequate consideration of both the people and structure safety is a crucial goal in a rational fire design. However, only a partial agreement concerning the general structural fire safety approach exists, and several meaningful discrepancies concerning the design and verification methods can be found in the context of European regulations. Due to counterpoising effects of those aspects, it is not possible to a-priori evaluate which approach leads to the safest or the most economical design. A detailed study of the different aspects and a comparison of the resulting designs is therefore of interest. Furthermore, the method based on prescriptive procedures is not free of design limitations and does not provide detailed information about the structure’s performance under high temperature, which is often crucial if a disproportionate collapse must be avoided. The more advanced approach of performance-based fire design (PBFD) becomes therefore more and more popular. A higher design flexibility based on performance objectives constitutes a beneficial and competitive concept within the structural fire safety engineering, ensuring a higher safety level of a design choice. The aim of this paper is to present the diversity in fundamentals, procedures and solutions of the two foregoing approaches. The aim is primarily accomplished through the detailed case-study analysis of an open car-park in compliance with the European and Scandinavian prescriptive regulations. Furthermore, the advanced methodology of the performance-based fire design approach is considered, with the avail of computer-aided simulations of the main frame of the car-park. Nonlinear analyses, with respect to thermally induced effects and emphasis laid to the collapse modality, are carried out on a frame of the considered structure with the avail of a commercial finite-element code.