عنوان مقاله [English]
The piers of many bridges in our country, which were constructed long ago, have been exposed to corrosive factors throughout the years and, in many cases, these factors have caused destructive effects. Creating a new 3D analytical model that can consider the effects of the corrosion of reinforcement on concrete columns and using the proper model for nonlinear finite element analysis is the main objective of this research. As corrosion basically causes a reduction in the strength of materials and consequently decreases the capacity of the bridge piers, consideration of their real behavior is of great importance. There are also some other factors which affect the nonlinear behavior of reinforced concrete structures, such as the stress-strain relation of concrete in compression, cracks in concrete, the crushing of concrete, aggregate interlock and dowel action. In addition, the corrosion of reinforcements is one of the crucial causes in affecting the nonlinear behavior of concrete structures, by which the loading capacity and ductility of concrete structures are reduced. Therefore, this factor is also considered using two main approaches, which are: reduction in the area of reinforcements and the bonding of concrete to the reinforcements, which are utilized in the tension stiffening model and in the variation of steel properties. In this study, the aforementioned causes are introduced with credited well-known relations and they are used in the presented model. It is also worthy to note that in this study, three rectangular columns are modeled in a new finite element program, using an advanced composite element, named; the Solid Shell Element, in two different cases. In one case, the corrosion effects of reinforcements are considered, while, in the other case, the corrosion effects are ignored and the analysis results of the two models are compared to those of laboratory experiments.