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ABSTRACT In this paper the problem of evaluation of the structural response of 1.20 m x 1.20 m blockwork masonry panels under monotonic shear and diagonal-compression tests is investigated. The [...]

ABSTRACT In this paper, three approaches with different levels of accuracy and approximation are proposed and critically discussed with the aim to model the non-linear out-of-plane response of three-leaf masonry [...]

Masonry arches and their typical failure do not fall elegantly into standard design and analysis methods. The system is highly dependent on geometry and failure is dominated by mechanization, not material strength. Focusing directly on the mechanized failure, this work presents the kinematic collapse load calculator (KCLC) for circular arches. The KCLC, a MATLAB® based graphical user interface, provides a simple interactive limit analysis of any ideal semi-circular masonry arch subjected to either an asymmetric point load or constant horizontal acceleration. After defining key geometric factors, the KCLC analyses the arch for any selected and kinematically admissible hinge configuration. For a selected configuration, an equilibrium approach to the upper bound theorem of limit analysis is used to calculate the collapse load multiplier and hinge reactions. The resulting collapse condition values are displayed and used to plot the thrust line that maintains a zero moment at the hinges. Designed primarily as an educational tool, the KCLC also provides a simple and efficient foundation for adapting to different arch geometries and loading conditions.

In assessing the safety of existing buildings, the specific actions dedicated to the knowledge of the structure delineate the parameters of the linear or non-linear analysis aimed at identifying the most appropriate structural intervention. In this context, the present paper collects the seismic analysis of a school building in reinforced concrete, illustrating the different stages concerning the acquisition of geometrical and mechanical data, problems about structural modelling and the features of the seismic retrofitting proposed. In closing, a critical comparison between the results derived from some techniques frequently used to seismically improve existing structures.

A computational model for evaluating the dynamical response and the damage of large masonry walls subjected to out-of-plane seismic actions is presented. During earthquakes, these actions are often the main cause of damage for the front wall and lateral walls of old masonry-built churches and monuments. Since the crack patterns often tend to subdivide the plane walls into a number of blocks, the model assumes such walls as a series of quadrilateral plane rigid elements connected to each other in the middle of their adjoining sides. Only the out-of-plane displacements are considered, and the connections are regarded as spherical elasto-plastic joints which allow rotations whose axis is in the plane of the undeformed wall. The hysteretic characteristics of these joints are defined so as to approximate the brittle behaviour of masonry material and the degradation due to cyclic loadings. The numerical results obtained using a limited number of elements show that the global out-of-plane response of the masonry walls and the mechanical degradation at each connection are in accord with the observed behaviour of real churches hit by strong earthquakes. Copyright © 2000 John Wiley & Sons, Ltd.

The semi-empirical assessment of seismic vulnerability of ancient church buildings is possible only if sufficient knowledge of the expected seismic behavior is available for a wide variety of typologies. For this reason, the information inferred from seismic damage observation may need to be complemented by numerical analysis. A simplified material model is proposed here for predicting the damage from out-of-plane behavior of large walls in old masonry churches subjected to seismic loading. For a specific substructure, the church façade, the effects of geometry, strength and post-elastic behavior of the material, as well as excitation characteristics are then analyzed with reference to the formation of a collapse mechanism. Comparison with observed damage thoroughly confirms the crack patterns developed numerically. Thence, the material model proposed may be considered satisfactory and suitable for use in seismic vulnerability studies.

A fibre model to describe the global dynamic response of slender masonry towers is presented for use in deterministic vulnerability analysis. The main stresses are axial in this type of structure, and coupling between flexural and axial modes in the inelastic region may be critical. The model accounts for the three-dimensional response of the structure and the relations between coupling effects and masonry characteristics. An exhaustive parametric study revealed that compression strength and height are the most important parameters determining global response to seismic excitation, and that the response is often very sensitive to the vertical component of the ground motion. The combination of flexural and axial vibrations can induce serious additional damage that should be considered in seismic risk analysis.