On the effect of thermal expansion coefficient in prestressed concrete beams

Abstract

Prestressed concrete beams are commonly employed for building concrete slabs. These structures could be exposed to accidental fires and recently there has been a significant effort to understand how them perform under extreme load conditions. One key issue is the stress state of prestressed concrete beams subjected to thermal loads because stresses vary in time according to the temperature profile and are added to the prestressing process. For high temperature and transient thermo-mechanical analysis, temperature-dependent properties are extensively employed. Slender structures, like prestressed beams, are particularly sensitive to temperature changes, unlike the more robust cross-sections found in reinforced concrete. Particularly this paper analyses the structural influence of the coefficient of thermal expansion in slender structures subjected solely to high temperature through validation with experimental tests. Additionally, subjecting the structure only to a temperature rise does not overlap for other effects such as mechanical loads. The mechanical response of the tests under high temperature is noteworthy, and the finite element numerical analysis is used to properly capture the influence of the temperature-dependent coefficient of thermal expansion in these structures. A better understanding of this problem is achieved and structural engineers could be aware of the use of commonly used temperature-dependent properties into their assessments.