Project Objectives

Additional developments concerning the derivation of fragility curves are still required for particular, less common, building typologies, namely old masonry constructions. A main goal of the project will be to derive fragility curves for the masonry constructions encountered in Lisbon.

For that it is required to characterize, from a structural point of view, these constructions, including, among others, their typologies, materials, dynamic characteristics, stage of conservation. Having all the elements essential to characterize the constructions, one needs to assess their seismic behaviour and decisions have to be made regarding the type of theoretical and numerical and experimental tools that are available and best suited for each case. Finally, one has to know how to use these tools to assess the performance of these structures under different severity levels of the seismic action, in other words, to assess the seismic vulnerability. For this the mechanical approach will be privileged given the specificness of the constructions analysed conjugated with their importance. For that simplified non-linear static methods and, in particular cases, non-linear dynamic analysis will be performed so as to validate the previous. The numerical tools to be used will be state-of-the-art macro-element software. This has proved to be a very good cost-effective tool, in terms of reliability and time consumption, to analyse these type of structures, and especially when compared to refined non-linear finite element analyses.

Experimental evidence, whenever possible, is valuable to back-up theoretical and numerical studies, both for validation and calibration reasons. In the case of old constructions it is even more valuable as the variety of configurations and materials which can be encountered is such that a constitutive model which is valid for one type may not be valid for another. Thus, given the singularity of some of the analysed constructions not many information can be found in the literature both national or intentional (from a structural engineer and not a rehabilitation technician point of view). Thus, another relevant objective to the project is to carry out some experimental studies for seismic assessment purposes. With respect to strength and stiffness of a wall (or pier) subjected to in-plane shear, tests on panels (rather than single material tests) are the most reliable information for the calibration of any analytical model to be used in seismic assessment. Since flexural strength is based on rather reliable and simple formulations, tests should aim to give information on shear failure.

The study would not be complete without a focus on possible retrofitting strategies for the specific structural weaknesses and typologies encountered in the analysed classes of buildings. The establishment of criteria for the selection of the intervention scheme for buildings is an issue still open to current research. The aim is to identify a set of suitable retrofitting strategies for these old masonry buildings and for different performance levels. Some particularities are encountered when dealing with old structures mainly due to the necessity to preserve its patrimonial value.

 

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