Collapse displacements of masonry arch with geometrical uncertainties on spreading supports

This work is aimed at evaluating the collapse displacement of masonry arch subjected to spreading supports. This is achieved through a general application of the virtual works principle. The problem is described in a finite displacements formulation and investigated with a probabilistic approach, also considering the effects of the geometrical uncertainties. This aspect is related to the imperfections of the voussoirs, which affect the structural shape. The comparison between the numerical and experimental results, derived both by the literature and laboratory tests, confirms that the geometrical irregularities can significantly affect the results obtained on the nominal structural geometry. Moreover, the disagreement observed in the experimental tests is explained

Dynamic response of masonry arch with geometrical irregularities subjected to a pulse-type ground motion

Ancient masonry structures often rely on the masonry arch as a load bearing element. The understanding of its response under seismic actions is a first fundamental step towards the comprehension of the behaviour of more complex structures. It is well known that the stability of masonry arches is primarily related to the geometry. The safety assessment under seismic actions is usually carried out by considering known deterministic geometrical parameters, such as thickness, rise and span, and the voussoirs are assumed with equal dimensions. However, many factors, like defects or irregularities in the shape of the voussoirs and imprecise construction, produce variations of the geometry with respect to the nominal one and, as a consequence, may effect the ability of the arch to resist seismic actions. In this paper, the effect of geometrical irregularities on the dynamic response of circular masonry arches is considered. Irregular geometries are obtained through a random generation of the key geometrical parameters, and the effect of these irregularities is quantified by analysing the dynamic response to ground motion. The masonry arch is modelled as a four-link mechanism, i.e. a system made of three rigid blocks hinged at their ends. The position of the hinges at the instant of activation of the motion is determined through limit analysis. Lagrange’s equations of motion have been written for the generated irregular geometries and solved through numerical integration. The results are summarised by a fragility surface that quantify the extent to which geometrical uncertainties can alter the dynamic response of the masonry arch and increase its seismic vulnerability

effect of geometric irregularities on the dynamic response of masonry arches

Abstract In this paper, the effect of geometric irregularities on the dynamic response of circular masonry arches is considered. Irregular geometries are obtained through a random generation of the key geometric parameters, and the effect of these irregularities is shown by modelling the dynamic response to ground motion. The masonry arch is modelled as a four-link mechanism, i.e., a system made of three rigid blocks hinged at their ends, where the position of the hinges at the instant of activation of the motion is determined through limit analysis. Lagrange's non-linear equations of motion have been solved through numerical integration. The results show that geometrical uncertainties produce an alteration of the mechanical features of the rigid blocks which may reduce the seismic capacity

On the Combined Use of Ground Penetrating Radar and Crack Meter Sensors for Structural Monitoring: Application to the Historical Consoli Palace in Gubbio, Italy

The paper deals with joint use of non-invasive monitoring technologies and civil engineering analysis methods aimed at providing multi-sensing information about the structural health of historical and cultural assets. Specifically, linear variable displacement transducers (LVDT) and ground penetrating radar (GPR) are considered for monitoring a significant crack affecting the Consoli Palace in Gubbio, Italy, precisely one of the walls of the cross-hall leading to the Loggia. In this frame, LVDT is adopted to control horizontal amplitude variations of the crack, while GPR is applied to investigate the wall interior and to detect the occurrence of inner issues related to the visible appearance of the crack on the wall surface. The effectiveness of GPR surveys is improved by means of a microwave tomography-based data processing strategy. The main result is that there is a consistency between the monitoring outputs of LVDT, which allowed us to display the crack widening/contraction due to the seasonal temperature variations, and the fact that no significant changes of the geometry of the inner areas of the walls were observed by the GPR

Experimental Tests on FRCM and FE Modelling for the Heritage Structure‘s Reuse

This paper presents the first results of an ongoing research in partnership with Kimia S.p.A. company (Italy). In particular, experimental tests on masonry specimens reinforced with Fiber Reinforced Cementitious Matrix (FRCM) have been recently conducted by Kimia according to the up-to date guidelines: specifically the single-lap shear test. On the base of the experimental results, a finite element model has been developed in order to reproduce the actual behaviour of the specimens. The results, derived both by the experimental tests and the FE model calibration, constitute the basis for planning an experimental campaign on masonry walls strengthened by FRCM loaded in the plane. The constructive details of the experimental set-up, conceived in order to create a self-balanced system and to bring the specimens to failure, are described together with a preliminary numerical modeling based on the already done test

Minimum Thickness and Collapse Conditions of the Irregular Masonry Arch Subject to its Own Weigth

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Earthquake-induced damage localization through non-linear dynamic analysis

The development of vibration-based long-term SHM methods for damage detection and preventive conservation of historic masonry buildings is receiving a growing trend of scientific interest. At the state of the art, well-acknowledged techniques for damage detection have been developed and validated, especially when dealing with earthquake-induced damages. The next scientific challenge to deal with in SHM is therefore damage localization, thus, not just detecting the occurrence of a damage, but also inferring, with a certain level of confidence, its location. This paper presents a methodology aimed at addressing the damage localization task in heritage masonry structures, based on Incremental Dynamic Analysis (IDA) carried out from a numerical model together with data recorded during the earthquake. IDA curves are built with reference to different portions of the structure, relating some local damage parameters (DMs) to some seismic or response intensity measures (IMs) and earthquake's intensity is used for locally identifying the damage in such portions. The choice of IM represents an important aspect of the IDA curves effectiveness and an appropriate study is carried out. The proposed methodology is validated through application to the numerical model of a reduced-scale masonry structure, called Brick House, which represents a well-known international benchmark case study tested on the LNEC-3D shaking table. The obtained results demonstrate that the proposed methodology is capable of achieving earthquake-induced damage detection and localization with a good level of aproximation.(undefined

Minimum Thickness and Collapse Conditions of the Irregular Masonry Arch Subject to its Own Weigth

The present paper aims at assessing the shape irregularities influence on the collapse conditions of masonry arches subjected to vertical point force. Surveys campaigns on cultural Heritage buildings often reveal masonry elements with irregular shapes. In order to accurately predict their actual behavior the presence of such features cannot be neglected. The reasons for these non-canonical shapes are manifold e.g. the evolution of degradation processes and the constructive laws. As a first analysis attempt, the geometrical uncertainties tied to the building work criteria are taken into account. A random parametric model is proposed to generate two-dimensional geometry of irregular polycentric arches. Monte Carlo simulations allows estimating the probabilistic density function of the collapse load multiplier evaluated by means of the implemented limit analysis method. The outcomes referred to the masonry arch with nominal geometry are compared to those obtained for the random polycentric arch, highlighting the extent of the load-bearing capacity reduction due to presence of such shape irregularities

Laser doppler and radar interferometer for contactless measurements on unaccessible tie-rods on monumental buildings: Santa Maria della Consolazione Temple in Todi

Non-contact measurements can be effectively used in civil engineering to assess the variation of structural performance with time. In the last decades this approach has received considerable interests from researchers working in the field of structural health monitoring (SHM). Indeed, non-contact measurements are very attractive because it is possible to perform non intrusive and non destructive investigations even being at a significant distance from the targets. Within this context, contactless measurements of the tie-rod vibrations in the Santa Maria della Consolazione Temple in Todi (Italy) are presented in this paper. In particular, laser vibrometer and radar interferometer measurements are used to estimate natural frequencies and mode shapes. This information is crucial to obtain the tensile axial force in the tie-rods, which can be used as an indicator of structural integrity or possible failure. Furthermore, a novel approach is proposed where drones (Unmanned Aerial Vehicles) can be successfully used to improve the effectiveness and the accuracy of the experimental activities

Am J Prev Med

CC999999/Intramural CDC HHS/United States2017-02-19T00:00:00Z26456878PMC531651