Damage Assessment, Characterization, and Modeling for Enhanced Design of Concrete Bridge Decks in Cold Regions.

摘要

Concrete has been used in dams, bridges, and highway pavements in which freeze-thaw process and cyclic loading are considered as important factors affecting its mechanical behavior during its service life. Damage caused by frost expansion is a primary concern when designing concrete structures in cold weather regions. It is known that the onset of damage within concrete can be accelerated when a freeze-thaw cycle occurs while a structure is subjected to an external loading. Also, concrete under fatigue loading gradually loses its strength with an increase in the number of load cycles regardless of the loading path (uniaxial or biaxial) and fails under loading significantly less than its strength. The strength reduction and more compliant behavior in concrete are due to widespread micro-cracks that form during freeze-thaw cycles as well as fatigue loading. Under such processes, the mechanical properties such as strength, stiffness, and ultimate strain are affected. In this report, changes in the mechanical properties for concrete and under fatigue loading and freeze-thaw cycles are investigated. Modern theories of damage mechanics with rate independent approach are extended to cover fatigue loading and freeze-thaw cycles. Different softening functions are proposed to predict the mechanical properties of concrete as the number of cyclic loading as well as freeze-thaw cycles increases. The results of the model are compared to the experimental data available in the literature that show a good correlation.