Seismic Hazard and Nonlinear Dynamic Analyses: Avoiding Collapse in Architectural Heritage

Abstract

Architectural heritage masonry buildings located in seismic areas are highly prone to suffer damage under seismic loading, due to their structural features. In this study, the Salares medieval tower, which is placed in the province of Malaga (Spain) - a zone with high seismic hazard in the Iberian Peninsula- is adopted as a case study. This is a precious heritage building which exhibits severe damages, such as depth cracks and inclination. Owing to those reasons detailed seismic and dynamic analyses are crucial for its preservation. The present work is arranged in three sections that deal with seismic hazard analysis, selection of real acceleration time-histories representative of the site, and dynamic response by means of numerical models. In order to obtain the design earthquake at the specific location, different parameters were analyzed, namely the region seismic activity, the geotechnical and geological conditions at the site and the acceptable risk level. Hazard analysis was performed following deterministic and probabilistic methods. As far as the seismic input is concerned, real accelerogram representative of the 1884 Andalusia earthquake were selected. It was a destructive earthquake that caused catastrophic damages near the analyzed structure. The accelerograms thus obtained were used as input for subsequent non-linear dynamic analyses on three-dimensional finite element models. Different cracking capable constitutive models were considered in order to predict local and global collapse mechanisms. Moreover, the suitability of each model was discussed when crushing, high plastic deformation or response under cyclic loading are concerned. The aforementioned studies yield significant results in order to perform a comprehensive safety assessment under ground motion effects. Thus, regarding the seismic input, the obtained accelerogram provides a relevant application aimed at revising the maximum acceleration and the response spectra of the Codes, as seismic code recommendations are limited in those issues. Furthermore, the dynamic structural response via numerical approach, allows determining damage propagation and collapse probability as a main step to select appropriate repair measures. The followed method could be used to assess and improve the structural strength of similar architectural heritage buildings located in active seismic areas.