A review of methods applicable to the study of masonry historical construction, encompassing both classical and advanced ones, is presented. Firstly, the paper offers a discussion on the main challenges posed by historical structures and the desirable conditions that approaches oriented to the modeling and analysis of this type of structures should accomplish. Secondly, the main available methods which are actually used for study masonry historical structures are referred to and discussed. The main available strategies, including limit analysis, simplified methods, FEM macro- or micro-modeling and discrete element methods (DEM) are considered with regard to their realism, computer efficiency, data availability and real applicability to large structures. A set of final considerations are offered on the real possibility of carrying out realistic analysis of complex historic masonry structures. In spite of the modern developments, the study of historical buildings is still facing significant difficulties linked to computational effort, possibility of input data acquisition and limited realism of methods.

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Structural Analysis of Masonry Historical Constructions. Classical and Advanced Approaches

Damage and performance evaluation of masonry churches in the 2009 L’Aquila earthquake

SUMMARY Recent seismic events have caused damage or collapse of invaluable historical buildings, further proving 7 the vulnerability of unreinforced masonry (URM) structures to earthquakes. This study aims to understand failure of masonry arches—typical components of URM historic structures—subjected to horizontal ground 9 acceleration impulses. An analytical model is developed to describe the dynamic behaviour of the arch and is used to predict the combinations of impulse magnitudes and durations which lead to its collapse. The 11 model considers impact of the rigid blocks through several cycles of motion, illustrating that failure can occur at lower ground accelerations than previously believed. The resulting failure domains are of potential 13 use for design and assessment purposes. Predictions of the analytical model are compared with results of numerical modelling by the distinct element method, and the good agreement between results validates 15 the analytical model and at the same time confirms the potential of the distinct element framework as a method of evaluating complex URM structures under dynamic loading. Copyright q 2007 John Wiley & 17 Sons, Ltd.

Failure of masonry arches under impulse base motion

Since the late 1970s, nonlinear static analysis have had an increasing use in the seismic assessment of existing unreinforced masonry (URM) buildings. Different modelling strategies can be used to evaluate the global seismic response of these buildings, such as the Continuous Constitutive Laws Model (CCLM) and the Equivalent Frame Model (EFM). Despite the CCLM modelling approach seems to be the most suitable at this aim, it needs many input data, which are often quite difficult to be known, and requires a high computational effort. For this reason, the EFM, which is based on strongly simplified hypotheses, is preferred in professional practice, where a small computational burden and a time- and cost-saving structural analysis by using few mechanical parameters is needed. In this paper, a review of its uses and limits is proposed, in order to identify the most critical issues and define its proper use in professional practice when applied to existing URM buildings. As a result, it is highlighted that the EFM can be reasonably used as a first conservative approach for the seismic assessment of existing URM buildings with box behaviour and quite regular opening patterns. Thus, up to now, from this review its use is encouraged in seismic analysis of existing URM buildings after providing them a reduction of their floors and roofs deformability, an adequate wall-to-floor and wall-to-roof connections and a regularization of the opening patterns.

Uses and limits of the Equivalent Frame Model on existing unreinforced masonry buildings for assessing their seismic risk: A review

Failure analysis of seven masonry churches severely damaged during the 2012 Emilia-Romagna (Italy) earthquake: Non-linear dynamic analyses vs conventional static approaches

A simplified procedure for assessing the seismic capacity of masonry arches

Geometrical patterns for diagrid buildings: Exploring alternative design strategies from the structural point of view

State of art in the worldwide evolution of base isolation design

SUMMARY
The originality of form is one of the new trends that can be identified in the current design of tall buildings. In this design trend, the so-called diagrid structures, which represent the latest mutation of tubular structures, play a major role due to their inherent esthetic quality, structural efficiency and geometrical versatility. In this paper, an overview on application of such typology to high-rise buildings is carried out; in particular, in the first part of the paper, the peculiarities of diagrid systems are described: starting from the analysis of the internal forces arising in the single diagrid module due to vertical and horizontal loads, the resisting mechanism of diagrid buildings under gravity and wind loads is described, and recent researches and studies dealing with the effect of geometry on the structural behavior are discussed. In the second part of the paper, a comparative analysis of the structural performance of some recent diagrid tall buildings, characterized by different number of stories and different geometries, namely the Swiss Re building in London, the Hearst Headquarters in New York and the West Tower in Guangzhou, is carried out, and some general design remarks are derived. Copyright © 2012 John Wiley & Sons, Ltd.

Antonello De Luca

Papers

Damage and performance evaluation of masonry churches in the 2009 L’Aquila earthquake

A simplified procedure for assessing the seismic capacity of masonry arches

Geometrical patterns for diagrid buildings: Exploring alternative design strategies from the structural point of view

State of art in the worldwide evolution of base isolation design

Diagrid structures for tall buildings: case studies and design considerations