Thermal Behavior and Structural Integrity of Structures

Unwanted fire has become one of the greatest threats to buildings. Concrete has very good behavior under fire due to its low thermal conductivity and non-combustibility. Concrete act as a protective cover to steel reinforcement and thus reinforced cement concrete shows good behavior under fire. However, there is a major problem caused by elevated temperatures that is the break of concrete masses from the surface of the concrete element, spalling phenomenon. Early thermal cracking of concrete often cause serious serviceability and durability problems, and thus should be carefully analysed and properly controlled. In power plant containment structure thermal loading has a noticeable influence on the loadingcapability of the structure. It is shown even a pure thermal load, i.e., a 150◦C temperature variation across the containment wall, can cause some damage to the concrete containment. The damage is further deepened by a simultaneous thermal loading. So using rubberized concrete in these structures helps to improve both thermal and mechanical behavior. In this study, an analysis of the mechanical and thermal properties of a sustainable concrete incorporating crumb rubber (CR) and steel or plastic fibers partially coated with rubber (FCR) is presented. CR is good as an aggregate because it dissipates impact energy, it reduces the risk of high-strength concrete spalling with fire. On the other hand, it reduces concrete stiffness without a high strength loss. CR presents a good thermal and sound absorption in concrete, so it can be also used in many construction composites. Detailed three-dimensional finite element models were set up to study the dynamic response and the possible damage of the power plant containment dome for different proportion of CR and FCR ie, 20%, 40%, 60%, 80%, 100% by the replacement of course aggregate. In addition, the influence of the thermal loading was investigated by setting up a thermal-mechanical coupling finite element model exposed to fire is presented.