A Novel Procedure for Simplified Nonlinear Numerical Modeling of Structural Units in Masonry Aggregates

Historical centers are always composed of masonry building aggregates often designed without respecting seismic design criteria. The current seismic Italian code does not foresee a clear calculation method to predict their static nonlinear behavior. For this reason, in this article the seismic response of structural units into masonry aggregates has been predicted through a simplified modeling approach. The implemented procedure has been calibrated on the results of a numerical model performed by using the Equivalent Frame Method (EFM), implemented within a Finite Element Method (FEM) calculation program, used to investigate a basic building compound representative of the constructive techniques developed in the past decades in the Southern Italy. First, the whole aggregate has been modeled and analyzed in the nonlinear static field in order to evaluate the seismic behavior of both intermediate and head structural units. Later on, the seismic response of these structural units, considered as isolated structures, has been assessed by considering in simplified way their position in the aggregate, as well as the influence of other constructions. Finally, the achieved results on the above single analysis cases have been compared with those deriving from the investigation of the whole building compound, allowing to confirm the effectiveness of the proposed novel analysis procedure.