Thermo‐Mechanical Analysis of Roller Compacted Concrete (RCC) Dams (Jahgin Dam)

Abstract

In this paper a procedure for two‐dimensional unsteady thermo‐mechanical analysis of layered structures is presented, allowing the determination of the temperature and stress field at each step the construction period. The finite element method is employed in the methodology. Numerical simulation are focused on concrete structures, particularly roller compacted concrete (RCC) dams. A time varying elasticity modulus is introduced in the model. One case study is presented and analysis under different design approaches. Thermal effects must be considered in the process of designing of certain types of concrete structures in order to prevent the damage during either the construction phase (early age cracking) or during the exploitation phase. The structures for which this problem is particularly important include concrete dams and other massive elements. In case of massive concrete structures, cracks can occur due to the combined effects of the heat generated by hydration of cement, heat transfer due to conduction, convection, thermal radiation and solar radiation and mechanical resistance of concrete after placement. In recent years, dams are being constructed using the Roller Compacted Concrete (RCC) technology, which (due to reduced thickness of individual lifts) is more favorable from the point of view of heat dissipation. Usually, in this technology the thickness of the individual lifts varies from 0.30 to 0.50 m. Modeling thermal processes is essential for the analysis of many structural problems. The purpose of this work is to present a methodology for unsteady thermal analysis of layered structures. The subject of the present work is the computation of stresses and strains caused by temperature variations that occur during the relatively rapid cooling and the consequent contraction of concrete in RCC dams. According to the conclusions of this research, the season of starting and the schedule of structure are so important in tensile stresses and the most critical state for tensile stresses will be occur when a maximum temperature zone is located at the first RCC layers therefore.