Partial factor durability design rules for carbonation of concrete structure

An essential method for durability design of concrete structures is the probability-based limit states method.The limit state function of durability is established first based on the model which describes the deterioration process,and then the characteristic values of concerned random variables and partial factors are determined.Hence,the design values of durability indexes can be determined which ensure the structures achieve an acceptable reliability with respect to the considered limit states.One of the key issues in process of durability designing depends on selecting the optimal design parameters.The parameters should be chosen based taking into account their physical meanings,reception level by the designers and the statistical regularity involved.The design methodology proposed is based on reliability theory traditionally used in the structural design and with the aid of a theoretical empirical combined model which describes the development of carbonation of concrete.The suggested values of target reliability index describing the acceptance probability of carbonation depth are proposed.The partial factors which are able to satisfy the requirement of target reliability index are evaluated.The purpose of the design rules is to ensure that the concrete structures that corrosion of reinforcement are not allowed will achieve the required service life under the common atmospheric environment condition.The different sets of concrete cover thickness and concrete strength which can satisfy the durability requirements.