Effect of long-term loading and fire temperatures on mechanical properties of concrete

Abstract

During a fire, reinforced concrete structures are exposed to high temperatures and subjected to long-term action of variable and permanent loads. This paper deals with analysis of influence of fire temperatures and long-term action of loads on compression strength and deformability of normal weight concrete. Results of experimental investigations of compression strength and deformability of normal-weight concrete subjected to long-term load and exposed to high temperature are presented. Specimens in the shape of prisms of normal-weight concrete were subjected to long-term compression of intensity η(t) = σc/fc(τ) = 0,3. The long-term compression was sustained for 400 days. Some of the specimens were heated (at 250 °C and 450 °C) before application of long-term load; other specimens were heated after application of long-term load. The paper presents coefficient of service conditions for concrete subjected to long-term load and exposed to high temperature that gives opportunity to evaluate compression strength and deformation properties of concrete.