Thermal stresses in concrete structures.
Thesis DisciplineCivil Engineering
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
This thesis considers the thermal response of mass concrete structures under heat-of-hydration effects, and of cracked reinforced and partially prestressed concrete bri.dges under diurnal insolation and ambient thermal fluctuations. The development of a linear heat-flow model for predicting temperatures (including heat-of-hydration effects) and stresses (including creep and shrinkage effects) is presented. Predictions from the model were found to agree well with experimental and other theoretical results. An experimental programme investigating the thermal response during transient heating of four concrete model beams, scaled from prototype bridges, under various load combinations and distributions of cracking is described. The models consisted of two 1/5th scale reinforced concrete T-section beams (one simply supported and one continuous), one continuous 15th scale prestressed box-girder and one continuous 1/7th scale prestressed T-section beam. Measurements were taken of temperatures and thermal deflections, concrete and steel strains, crack widths and continuity forces. Theoretical methods capable of predicting the thermal response of simply supported and continuous concrete bridges, including the effects of cracking, are developed. Theoretical predictions based on the theory are compared with experimental results, and the significance of cracking on the thermal response assessed. The effect of cracking on the transverse thermal response of a box-section and double-spine T-section are analysed. The significance of thermal load on structures force loaded close to their ultimate capacity is studied.