Effect of fire on behavior of HSC columns

Despite the relative advantages of concrete structures over steel structures under fire, they could be extremely vulnerable. In this regard, high strength concrete is more susceptible than the conventional one. At high temperatures, changing the characteristics of concrete and reinforcement materials including their modulus of elasticity, failure strength, and a phenomenon called spalling which is associated with a reduction in cross section of concrete members causes the displacements to increase which finally leads to complete fracture of the structure. Stresses induced in concrete members during fire conditions are mainly due to their expansion and pressure of entrapped evaporated water of the concrete. Behavior of concrete due to its complexity is mainly evaluated using experimental tests. Because of the limitations of experimental studies, the behavior of concrete under fire condition is modeled using the finite element method. The effects of various parameters such as concrete cover,loading rate, strength, and etc. on the behavior of concrete columns including temperature and displacements are investigated. Results of this study showed that concretes with high cover, low preloading, siliceous aggregate and lower compressive strength had higher resistance in fire than other types.

Keywords:

High strength concrete , Column , Spallling , Standard fire