Effect of the Mechanical Properties of Concrete on the Seismic Assessment of RC Irregular Buildings

In this work the role of the effective concrete strength on the seismic assessment of RC buildings has been investigated. The concrete strength has been described after a wide investigation on the structural elements of a case-study, i.e. an existing building located in Sansepolcro (Italy), currently used as a Hospital. Alternative representations of the concrete strength distribution have been compared, consisting respectively of: assuming a uniform strength distribution for the entire structure (as required by the International Codes), assuming a mean storey strength at each storey and assigning to each tested member the strength value found by the experimental survey. The seismic performance of the building has been found with reference to three different limit states, by representing the structural response through a nonlinear static analysis and comparing the maximum chord rotation and shear stress to the limit values corresponding to the assumed concrete strength of each member. The effects of the actual distribution of the concrete strength have been finally checked by comparing the seismic performance obtained through the three different assumptions for concrete strength distribution.