MODELING OF CONCRETE SLABS UNDER FIRE

The ability to assess the integrity of concrete structures after a severe thermal shock is extremely important not only for fire safety but also for the economy. A mathematical model, capable of rationally determining of fire response and correctly simulating the heat and mass transfer in concrete structures has been developed. Based on the concept of continuum mechanics, the conservation of mass, momenta, and energy equations have been used to yield a set of three coupled nonlinear partial differential equations with time dependent nonlinear mixed boundary conditions. Approximately a finite difference model has been developed for simulating the concrete structure under fire. The discrete set of implicit finite difference equations, after being quasi-linearized, is used and solved by a computer. Efficiently controlling time-step, the running computing time is minimized without detrimental effects on accuracy. The numerical results predict the phenomenon of “moisture clog” and show that the permeability of concrete is an essential parameter. This parameter controls the buildup of pressure during the fire exposure. The explosive spalling of concrete under fire is predicted. © 1990, Taylor & Francis Group, LLC. All rights reserved.