This paper contains a seismic assessment at urban scale of the cities of Sion and Martigny in Switzerland. These two cities have been identified for the present research based on their importance regarding size and the characteristics of the building stock for which information was available. Moreover, microzonation investigations are available for both cities. This results in a more accurate characterization of local expected ground shaking, which is expressed through specific response spectra. Sion and Martigny represent, respectively, the capital and second largest city of the canton of Valais. This region is characterized by the highest seismicity within Switzerland. The paper focuses on the assessment using Risk-UE methodology, namely the empirical method LM1 and the mechanical method LM2. The obtained results are compared in order to assess the related accuracy. Firstly, buildings of the two cities were surveyed in order to collect main structural characteristics in a database. Building stock is typical of that region and can be found similar to many other medium-sized Swiss cities. Around half of the buildings are unreinforced masonry buildings, while several others are reinforced concrete buildings with shear walls. Results show the most vulnerable part of the cities regarding earthquake. There are significant differences in global results between LM1 and LM2 methods. The mechanical LM2 method is more pessimistic since it predicts damage grades of about one degree higher than LM1 method. However, the main drawback of the empirical LM1 method is that an a priori determination of an adequate value of the macroseismic intensity is required. Nevertheless, LM2 method may lead to a global overestimation of damage prediction.
A multidisciplinary approach for assessing the seismic vulnerability of heritage masonry buildings is described throughout the paper. The procedure is applied to a specific case study that represents a very common typology of masonry building in Italy. The seismic vulnerability of the examined building has been assessed after developing: (a) historical investigation about the building and the surrounding area, (b) detailed geometrical relieves, (c) identification of materials by means of surveys and literature indications, (d) dynamic in-situ tests, (e) foundation soil characterization, (f) dynamic identification of the structure by means of a refined Finite Element (FE) model. After these steps, the FE model has been used to assess the safety level of the building by means of non linear static analyses according to the provisions of Eurocode 8, and estimate of the \ud
q-factor. Some parametric studies have been also carried out by means of both linear dynamic and non linear static analyses
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