سید حامد معراجی

Reinforced concrete structures exposed to marine medium will experience damages in steel bars because of chloride percolation. This corrosion can damage concrete structures significantly and repair, inspection actions and maintenance costs for these structures can reach a comparable level with construction cost of new structures. So chloride percolation is a main factor that will affect durability of concrete structures. Commonly durable life of a structure is determined based on initial time of corrosion in steel bars that is calculated by amount of percolated chloride. In numerical simulation chloride distribution in concrete structures to estimate initial time of corrosion, it is important to use methods that have higher precision and convergence speed and simpler function than other old methods. One of these methods is “DQ” that can be a substitution to other known methods so in this research, DQ method is used to solve chloride distribution equation to estimate service life of concrete structures and initial time of corrosion in steel structures. Chloride ions distribution is considered based on second law of Fick. Bellman et all in 1972 introduced differential quadrature method to reach an effective technic and considered accuracy in numerical solutions by means of few network points in which partial derivatives of a function in one coordinate direction, is defined as weigh and linear sum of all function amounts in all network points in that direction. DQ method is developed from differential quadrature idea. The main key in DQ method is to determine weigh factor for derivatives discretization with each order . The aim of this research is to simulate chloride distribution in concrete structures for estimating initial time of corrosion. This research has also demonstrated that PDQ and RBF-DQ method shows more accurate results by less networks than other numerical methods.