Assessing the seismic vulnerability of masonry buildings - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 327

13
Assessing the seismic vulnerability of
masonry buildings
D. D ' AYA L A, University College London, UK
DOI : 10.1533/9780857098986.3.334
Abstract : Masonry structures represent the highest proportion of the
building stock worldwide and in regions affected by destructive
seismicity. Together with reinforced concrete buildings they account for
the largest proportion of casualties in earthquakes. However, well-built
masonry buildings have survived for centuries, even in regions of high
seismicity. In the past, seismic vulnerability assessment of masonry
structures has been conducted using empirical methods, based on
post-event collection of damage data. This approach does not allow easy
correlation of structural behaviour with observed damage and
quantifi cation of the effect of seismic strengthening on seismic resistance.
After an initial review of the main issues associated with the seismic
vulnerability assessment of masonry buildings, the chapter presents the
rationale and algorithm of a procedure based on limit state analysis and
collapse mechanisms (FaMIVE), to derive capacity curves for masonry
structures. It is shown how the procedure can be used to derive
vulnerability and fragility functions following the methodology of the
capacity spectrum method and the performance-based assessment
method. Treatment of model and data uncertainties concludes the
chapter.
Key words : masonry structures, seismic vulnerability, limit analysis,
damage states, capacity curves, performance points, uncertainty.
13.1 Introduction
Notwithstanding several decades of academic research into the seismic
behaviour of unreinforced masonry structures, their intrinsic vulnerability
to seismic action is perceived as defi cient. This is clearly manifested in
current seismic codes and standards worldwide that restrict this structural
type only to regions of low-to-moderate seismicity, allowing only for modest
span and height dimensions. Millennial evidence proves that masonry is a
sustainable and resilient material available to human kind, which is also
able to withstand earthquakes, if adequately built.
Seismic vulnerability analysis of masonry structures has traditionally
been carried out using 'empirical' (or statistical) methods. These can be
divided in categorisation methods, which classify buildings into typologies
characterised by propensity of damage, or inspection and rating methods,
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