Dynamic Monitoring and Seismic Response of a Historic Masonry Tower

Saisi, A.; Gentile, Carmelo; Guidobaldi, Marco; Xu, Man

doi:10.4028/www.scientific.net/kem.628.55

Cited by 10 publications

(10 citation statements)

References 7 publications

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“…Curves in Figure 13a confirm that, like in Figure 12a, the bell lasts in ringing right state over time; on the contrary, curves in Figure 13b show that, after some cycles, three in that case, the ringing state switches from wrong to right. In the figures, impacts obviously correspond to sudden variations, whose extents, recalling Equation (23) or (24), are inverse function of the adopted time step.…”

Section: Large Undamped Free Oscillationsmentioning

confidence: 99%

“…The inertia forces due to the swinging of the bell play a crucial role in dynamic identification [19] or assessment of existing bell towers [8][9][10][11][12][13][20][21][22][23][24][25], especially when the frequency of the bell oscillations is in the neighborhood of the relevant natural frequencies of the tower. Some analytical solutions for bell-tower interaction are given in [13], considering free oscillations and different mounting systems.…”

Section: Introductionmentioning

confidence: 99%

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Nonlinear Dynamics of Swinging Clapper Bells under Arbitrary or Resonant Forcing Functions

Croce¹

2020

Applied Sciences

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Study of swinging clapper bells involves aspects encompassing sound and acoustic engineering, mechanical engineering, and structural engineering. From the musical point of view, clapper bells are directly played idiophone instruments, where the playing device, the clapper, although directly excited, is not explicitly controlled by the bell ringer. The achievement of a clear and optimal sound mainly depends on the acoustic characteristics of the bell and on the regularity of the clapper strokes, which is not only governed by the ringing style and the relevant parameters of clapper and bell but also by the real time corrections to the excitation introduced by trained bell ringers. In fact, despite centuries of experience allowed to optimize the bell performances, standardizing proportions and mounting arrangements, effective sound control requires some fine tuning of the forcing function. Another crucial topic, especially in view of assessing existing structures, regards the evaluation of time histories of the actions transmitted by the bell to the pivots and the study of the interactions between the bell and the supporting structures, belfries, and bell-towers. “Ringability” of swinging bells and bell-structure interactions are usually tackled in the framework of rigid body dynamics, so arriving at an initial value problem, governed by a system of two second order nonlinear ordinary differential equations (ODEs), whose solutions are piecewise-defined functions. In the relevant literature, numerical solutions of the system are commonly sought using built-in algorithms provided in advanced software packages; since the use of such general algorithms is subject to some restrictions, especially regarding the forcing functions, validity of the results is often limited. The present study focuses on an innovative procedure to solve the equations of motion. The method, extremely fast and effective, is based on original numerical explicit-implicit predictor-corrector integration algorithms with constant time step, duly validated reproducing the outcomes of relevant reference case studies. Each time the clapper strikes the bell a new “piece” of the solution is initialized, so avoiding user interventions in the elaboration phase. Independently on the oscillation amplitude and on the duration of the considered time interval, the algorithms can successfully manage undamped oscillations; friction and viscosity damped oscillations; free oscillations in transient and stationary phases; and can be applied also to solve stiff equations. Furthermore, the capability of the proposed methods to deal with arbitrary forcing functions is particularly innovative. The outcomes of relevant case studies, regarding the oscillations of the old tenor bell of the Great St. Mary church in Cambridge, confirm the potentialities of the method, also highlighting some topical issues, involving, for example, the assessment of damping equivalence. Finally, a pioneering feature of the algorithms is their ability to handle and to define “resonant” forcing functions, continuously tuning the frequency of the excitation to the natural frequency of the oscillation, according to the oscillation amplitude.

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Section: Large Undamped Free Oscillationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nonlinear Dynamics of Swinging Clapper Bells under Arbitrary or Resonant Forcing Functions

Croce¹

2020

Applied Sciences

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“…A well-designed monitoring system could identify premature failures and prevent sudden collapses. Available traditional SHM systems for masonry structures are based on the evaluation of changes or anomalies in the structural behavior or in the modal properties of the structure, signs of a variation of stiffness or developments of crack patterns [10,11]. The reliability of these techniques depends on the number, the deployment and performance of each sensor.…”

Section: State-of-artmentioning

confidence: 99%

Applications of Smart Bricks for Strain Field Reconstruction in Masonry Walls: Numerical Analysis and Shaking Table Tests

D’Alessandro¹,

Meoni²,

Cavalagli³

et al. 2019

Proceedings of the 7th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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Masonry structures are particularly vulnerable to seismic loads due to their brittle and nonhomogeneous behavior. Therefore, assessing their conditions after significant events is especially critical: this could be achieved through a reliable monitoring system able to identify significant variations of strains and stresses which could induce cracks. To this aim, the authors developed a new clay-based smart brick sensor as a novel solution for strain monitoring of masonry elements fully integrated into the wall components. This paper is aimed at (i) improving understanding and modeling of the smart brick properties and (ii) investigating the application of such sensors for reconstructing the strain fields into masonry elements subjected to a variety of loading conditions. A particular attention is devoted to analyzing the optimal configuration for the detection of changes in the load paths. To this aim, a FE micro-modeling approach is first applied to a masonry wall. Then, a shaking table test on a full-scale masonry building is presented and results are compared to a FE macro-modeling simulation.

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“…6 In long-term vibration-based monitoring, a technique widely applied to historical structures as it involves the use of a limited number of sensors, anomalies in the global structural behavior are detected from the evaluation of changes in modal features, such us natural frequencies, caused by local modifications in structural stiffness occurred during the development of crack patterns. [7][8][9] Static parameters-based methods are employed to detect and assess local propagation and evolution of cracks and damages considering displacements, tilts, and strain measurements acquired using dedicated sensors, such as linear variable differential transformers (LVDTs), inclinometers, and resistive strain gauges (RSGs). 10 These approaches have the advantages of tracking local damages, even when they are not sufficiently severe to influence modal features, therefore overcoming a limit that affects dynamic monitoring systems.…”

Section: Introductionmentioning

confidence: 99%

Shaking table tests on a masonry building monitored using smart bricks: Damage detection and localization

Meoni

D’Alessandro

Cavalagli

et al. 2019

Earthq Engng Struct Dyn

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Summary The seismic behavior of unreinforced masonry buildings is typically characterized by premature brittle collapse mechanisms that can cause serious consequences for the protection of human lives and for the preservation of historical and cultural heritage. Structural health monitoring can be a powerful tool enabling a quick post‐earthquake assessment of the structure's performance, but its applications are still scarce as a consequence of the severe limitations affecting off‐the‐shelf sensing technologies, in terms of local nature of the measurements, costs, as well as long‐term behavior, installation, and maintenance. To overcome some of these limitations, the authors have recently proposed a new sensing technology, called “smart brick,” that is a durable clay brick doped with stainless steel microfibers, working as a smart strain sensor for masonry buildings. This paper presents the first full‐scale application of smart bricks, used for detecting and localizing progressive earthquake‐induced damage in an unreinforced masonry building subjected to shaking table tests. Smart bricks are employed to detect changes in load paths on masonry walls, comparing strain measurements acquired after each step of the seismic sequence with those referring to the undamaged structure. Experimental results are interpreted using a 3D finite element model built to reproduce the shaking table tests. Overall, the results demonstrate that the smart bricks can effectively reveal local permanent changes in structural conditions following a progressive damage, therefore being apt for earthquake‐induced damage detection and localization.

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Dynamic Monitoring and Seismic Response of a Historic Masonry Tower

Cited by 10 publications

References 7 publications

Nonlinear Dynamics of Swinging Clapper Bells under Arbitrary or Resonant Forcing Functions

Nonlinear Dynamics of Swinging Clapper Bells under Arbitrary or Resonant Forcing Functions

Applications of Smart Bricks for Strain Field Reconstruction in Masonry Walls: Numerical Analysis and Shaking Table Tests

Shaking table tests on a masonry building monitored using smart bricks: Damage detection and localization

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