Abstract

The ground motion vertical component is generally ignored in the analysis of ordinary building structures, even though observed damages after last earthquakes highlighted its marked influence especially on the response of masonry structures. In the present research work, the effect of ground motion vertical components in case of near-source excitations has been analysed. The investigation has been made on the Banloc Castle, a historical masonry building damaged by the Banat-Voiteg earthquake occurred on December 1991 in the Region of Banloc in Romania. A FEM model of the building, setup with the DIANA FEA analysis software, has been investigated in the non-linear dynamic field. In particular, the records have been referred to the Banloc site, located 7.01 km far from the epicentre with a moment magnitude Mw=5.5 and a focal depth of 9 km. The behaviour of the ground motion components has been characterised by the V/H peak ground acceleration ratio. In order to estimate the influence of the vertical seismic motion in terms of both displacements and stress regime, two different scenarios have been analysed. The first scenario has taken into account the horizontal component only, whereas the second one has analysed the simultaneous effects of three components of the seismic action. Finally, numerical damage patterns have been plotted aiming to simulate the real cracks detected in the case study after the considered seismic event.

Abstract

Several seismic events have demonstrated the vulnerability of masonry churches. The long seismic history of the Italian territory has provided materials to observe and to study the structural performance of churches. Since the 1976 Friuli earthquake many studies have contributed to the definition of specific damage and vulnerability assessment methods for churches, based on the identification of macro-elements and kinematic mechanisms. In this context, the paper presents the application of a vulnerability assessment methodology developed and currently applied in Italy to a case study representative of the néo-roman church typology in Montreal, Québec. The study is part of a collaborative project between Politecnico di Milano and École de Technologie Supérieure of Montreal. The relevance of such a study derives from the moderate seismicity of Montreal associated to a high density of churches. Starting from a previous inventory of 108 churches in Montreal Island, the Néo-roman church typology was selected to be investigated. Specificities of this typology are the position of the bell tower in the middle of the façade and the interaction between the timber structure and masonry walls. This combination between the façade and bell tower macro-elements requires to reconsider the mechanisms associated to these elements in the original reference method. A detailed survey of the roof and bell tower timber structures of a néo-roman church was done, and a three-dimensional numerical model was developed for a better understanding of this type of structure. Modal analysis of a global model was then carried out and the first results of the modal shapes discussed.

Abstract

The meaningful seismic events occurred in Italy in the last decades showed the high vulnerability of monumental buildings and in particular of churches. In order to preserve such a precious heritage, operations aimed at the seismic risk mitigation based on the definition of suitable vulnerability assessment procedure are necessary. The high hazard of the Italian Peninsula and the huge amount of ecclesiastic buildings located in the exposed territories, stress the need to face the problem with innovative large-scale approaches. In this study, an architectural-engineering integrated procedure for the seismic assessment of existing masonry churches at a regional scale is proposed. Based on accurate historical investigation of typical Abruzzi churches, a typological characterization has been established, aimed at recognizing the common geometrical and constructive features of two types of medieval churches widespread in this area. Then, a numerical analysis has been carried out. In particular, by assuming simplified modelling hypotheses, two FE models representative of significant real cases have been implemented in Abaqus. By the elastic analyses, the main collapse mechanisms and the corresponding activation seismic accelerations have been determined. The obtained outcomes show an acceptable correspondence with the actual seismic damage revealed on similar churches in the aftermath of last seismic events, corroborating the reliability of the adopted integrated approach.