Large-scale pool fires

A review of research into the burning behavior of large pool fires and fuel spill fires is presented. The features which distinguish such fires from smaller pool fires are mainly associated with the fire dynamics at low source Froude numbers and the radiative interaction with the fire source. In hydrocarbon fires, higher soot levels at increased diameters result in radiation blockage effects around the perimeter of large fire plumes; this yields lower emissive powers and a drastic reduction in the radiative loss fraction; whilst there are simplifying factors with these phenomena, arising from the fact that soot yield can saturate, there are other complications deriving from the intermittency of the behavior, with luminous regions of efficient combustion appearing randomly in the outer surface of the fire according the turbulent fluctuations in the fire plume. Knowledge of the fluid flow instabilities, which lead to the formation of large eddies, is also key to understanding the behavior of large-scale fires. Here modeling tools can be effectively exploited in order to investigate the fluid flow phenomena, including RANS- and LES-based computational fluid dynamics codes. The latter are well-suited to representation of the turbulent motions, but a number of challenges remain with their practical application. Massively-parallel computational resources are likely to be necessary in order to be able to adequately address the complex coupled phenomena to the level of detail that is necessary

Behaviour of concrete structures in fire

This paper provides a "state-of-the-art" review of research into the effects of high temperature on concrete and concrete structures, extending to a range of forms of construction, including novel developments. The nature of concrete-based structures means that they generally perform very well in fire. However, concrete is fundamentally a complex material and its properties can change dramatically when exposed to high temperatures. The principal effects of fire on concrete are loss of compressive strength, and spalling - the forcible ejection of material from the surface of a member. Though a lot of information has been gathered on both phenomena, there remains a need for more systematic studies of the effects of thermal exposures. The response to realistic fires of whole concrete structures presents yet greater challenges due to the interactions of structural elements, the impact of complex small-scale phenomena at full scale, and the spatial and temporal variations in exposures, including the cooling phase of the fire. Progress has been made on modeling the thermomechanical behavior but the treatment of detailed behaviors, including hygral effects and spalling, remains a challenge. Furthermore, there is still a severe lack of data from real structures for validation, though some valuable insights may also be gained from study of the performance of concrete structures in real fires.

BEHAVIOUR OF CONCRETE STRUCTURES IN FIRE by

This pa per pro vides a “state-of-the-art ” re view of re search into the ef fects of high tem per a ture on con crete and con crete struc tures, ex tend ing to a range of forms of con struc tion, in clud ing novel de vel op ments. The na ture of con crete-based struc tures means that they gen er ally per form very well in fire. How ever, con crete is fun da men tally a com plex ma te rial and its prop er-ties can change dra mat i cally when ex posed to high tem per a tures. The prin-ci pal ef fects of fire on con crete are loss of com pres sive strength, and spalling – the forc ible ejec tion of ma te rial from the sur face of a mem ber. Though a lot of in for ma tion has been gath ered on both phe nom ena, there re mains a need for more sys tem atic stud ies of the ef fects of ther mal ex po-sures. The re sponse to re al is tic fires of whole con crete struc tures pres ents yet greater chal lenges due to the in ter ac tions of struc tural el e ments, the im-pact of com plex small-scale phe nom ena at full scale, and the spa tial and tem po ral vari a tions in ex po sures, in clud ing the cool ing phase of the fire. Prog ress has been made on mod el ling the thermomechanical be hav iour but the treat ment of de tailed be hav iours, in clud ing hygral ef fects and spalling, re mains a chal lenge. Fur ther more, there is still a se vere lack of data from real struc tures for val i da tion, though some valu able in sights may also be gained from study of the per for mance of con crete struc tures in real fires