11 research outputs found
De la caractĂ©risation du mouvement sismique associĂ© Ă des sĂ©ismes historiques : Ă©tude de SantâAgata del Mugello en associant archĂ©ologie de la construction, gĂ©nie sismique et sismologie
La dĂ©formation accumulĂ©e pendant plusieurs centaines (milliers) d'annĂ©es dans les zones de failles est brusquement relĂąchĂ©e en seulement quelques secondes lorsqu'un sĂ©isme se produit. L'Ă©tude des sĂ©ismes anciens Ă travers diffĂ©rentes Ă©chelles de temps est d'une importance capitale pour amĂ©liorer l'Ă©valuation de l'alĂ©a sismique. Au cours des derniĂšres dĂ©cennies des approches alternatives, telles que la sismologie historique, l'archĂ©osismologie et la palĂ©osismologie ont Ă©tĂ© dĂ©veloppĂ©es pour chercher des sources d'informations. Parmi elles, les bĂątiments historiques, tels des "sismomĂštres de pierre" peuvent ĂȘtre utilisĂ©s pour tĂ©moigner de cette sismicitĂ© passĂ©e qu'ils ont enregistrĂ©e dans leurs murs sous forme de dĂ©gĂąts ou de rĂ©parations. Je propose une mĂ©thodologie innovante reliant l'archĂ©ologie de la construction, la sismologie et le gĂ©nie sismique afin de dĂ©montrer que la caractĂ©risation archĂ©ologique des rĂ©parations post-sismiques sur les bĂątiments historiques peut permettre de dĂ©duire les principales caractĂ©ristiques du mouvement sismique. Cette mĂ©thodologie est dĂ©veloppĂ©e autour du cas de l'Ă©glise mĂ©diĂ©vale de Sant'Agata del Mugello, un site exceptionnel dont les dommages et les rĂ©parations induits par les sĂ©ismes sont dĂ©crits par de nombreuses sources historiques. Le site est situĂ© dans le bassin du Mugello (Apennin central, Italie, Toscane), caractĂ©risĂ© par une sismicitĂ© modĂ©rĂ©e. Les plus grands Ă©vĂ©nements connus se sont produits en 1542 (Mw ~ 6) et 1919 (Mw ~ 6.3). Nous commençons par retracer l'histoire sismique de l'Ă©glise en combinant une analyse stratigraphique du bĂątiment avec une Ă©tude approfondie des textes historiques. Un modĂšle de CAO est conçu Ă partir d'un relevĂ© gĂ©omĂ©trique issu d'une campagne de scanner laser. Un modĂšle de CAO de l'Ă©glise avant et aprĂšs chaque sĂ©isme historique est ensuite extrapolĂ© Ă partir du modĂšle de l'Ă©glise actuelle et de son histoire constructive. Un code de maillage ad hoc a Ă©tĂ© dĂ©veloppĂ© pour gĂ©nĂ©rer un maillage aux Ă©lĂ©ments finis Ă partir du modĂšle de CAO. Deux campagnes de vibrations ambiantes ont Ă©tĂ© menĂ©es dans l'Ă©glise de Sant'Agata. 8 modes de vibration (frĂ©quence propre, dĂ©formĂ©e modale et amortissement) sont estimĂ©s. Un processus d'optimisation des paramĂštres modaux, permet de calibrer le modĂšle numĂ©rique de l'Ă©glise dans sa partie linĂ©aire. Un modĂšle d'endommagement continu est utilisĂ© pour identifier la limite du modĂšle linĂ©aire de l'Ă©glise. Je me concentre ensuite sur l'Ă©tude du sĂ©isme historique de 1919 qui n'a pas causĂ© de dommages. Une collection de mouvements sismiques compatibles avec le contexte sismotectonique est sĂ©lectionnĂ©e, corrigĂ©e et est utilisĂ©e pour simuler le modĂšle numĂ©rique linĂ©aire calibrĂ© de l'Ă©glise. Je prĂ©sente des rĂ©sultats prĂ©liminaires pour discuter des caractĂ©ristiques du mouvement sismique associĂ© au sĂ©isme historique de 1919.A fault is charged during (hundred-) thousand years, then the accumulated elastic energy is released in few seconds when an earthquake occurs. To correctly assess seismic hazard it is of capital importance to study the seismic history. Over the last decades alternative approaches such as historical seismology, archaeoseismology and paleoseismology have been developped chasing alternative sources of information. Among them, historical buildings witnessed ancient earthquakes as âstone seismometersâ recorded in their walls as structural disorders and repairs. I develop an innovative methodology connecting building archaeology, seismology and earthquake engineering. I aim to show that archaeological characterization of post-seismic repairs on historical buildings can successfully infer key ground motion characteristics of historical earthquakes. The test case is the medieval church of SantâAgata del Mugello, an exceptional site with many historical sources describing the damages induced by past earthquakes, and their renovation. The site is located in the Mugello basin (Central Apennines, Italy, Tuscany), characterized by a moderate seismicity. The largest known events occurred in 1542 (Mw~6) and 1919 (Mw~6.3). I first trace the seismic history of the church by combing a stratigraphic analysis of the buidling with an in-depth study of historical texts. A CAD-based model of the current church is designed from a laser scanner survey. A CAD-model of the church before and after each historical earthquake is then extrapolated from the current church and its deduced constructive history. I have developed an textit{ad hoc} meshing code to generate a finite element mesh from the CAD-based model. We perform two ambient vibration testing surveys in the church. 8 modes of vibration (natural frequency, modal shapes and damping ratio) are estimated. A Vibration-Based model updating based on the identified experimental parameters and the constructive history of the church allows to calibrate the numerical model of the church in its linear part. A continuum damage model is used to identify the limit of the linear model of the church. I then focus on the study of the 1919 non damaging earthquake. A collection of waveforms compatible with the seismotectonic context is selected, corrected, and used to simulate the updated linear digital model of the church. I show preliminary results to discuss the ground motion characteristics of the 1919 earthquake
De la caractĂ©risation du mouvement sismique associĂ© Ă des sĂ©ismes historiques : Ă©tude de SantâAgata del Mugello en associant archĂ©ologie de la construction, gĂ©nie sismique et sismologie
A fault is charged during (hundred-) thousand years, then the accumulated elastic energy is released in few seconds when an earthquake occurs. To correctly assess seismic hazard it is of capital importance to study the seismic history. Over the last decades alternative approaches such as historical seismology, archaeoseismology and paleoseismology have been developped chasing alternative sources of information. Among them, historical buildings witnessed ancient earthquakes as âstone seismometersâ recorded in their walls as structural disorders and repairs. I develop an innovative methodology connecting building archaeology, seismology and earthquake engineering. I aim to show that archaeological characterization of post-seismic repairs on historical buildings can successfully infer key ground motion characteristics of historical earthquakes. The test case is the medieval church of SantâAgata del Mugello, an exceptional site with many historical sources describing the damages induced by past earthquakes, and their renovation. The site is located in the Mugello basin (Central Apennines, Italy, Tuscany), characterized by a moderate seismicity. The largest known events occurred in 1542 (Mw~6) and 1919 (Mw~6.3). I first trace the seismic history of the church by combing a stratigraphic analysis of the buidling with an in-depth study of historical texts. A CAD-based model of the current church is designed from a laser scanner survey. A CAD-model of the church before and after each historical earthquake is then extrapolated from the current church and its deduced constructive history. I have developed an textit{ad hoc} meshing code to generate a finite element mesh from the CAD-based model. We perform two ambient vibration testing surveys in the church. 8 modes of vibration (natural frequency, modal shapes and damping ratio) are estimated. A Vibration-Based model updating based on the identified experimental parameters and the constructive history of the church allows to calibrate the numerical model of the church in its linear part. A continuum damage model is used to identify the limit of the linear model of the church. I then focus on the study of the 1919 non damaging earthquake. A collection of waveforms compatible with the seismotectonic context is selected, corrected, and used to simulate the updated linear digital model of the church. I show preliminary results to discuss the ground motion characteristics of the 1919 earthquake.La dĂ©formation accumulĂ©e pendant plusieurs centaines (milliers) d'annĂ©es dans les zones de failles est brusquement relĂąchĂ©e en seulement quelques secondes lorsqu'un sĂ©isme se produit. L'Ă©tude des sĂ©ismes anciens Ă travers diffĂ©rentes Ă©chelles de temps est d'une importance capitale pour amĂ©liorer l'Ă©valuation de l'alĂ©a sismique. Au cours des derniĂšres dĂ©cennies des approches alternatives, telles que la sismologie historique, l'archĂ©osismologie et la palĂ©osismologie ont Ă©tĂ© dĂ©veloppĂ©es pour chercher des sources d'informations. Parmi elles, les bĂątiments historiques, tels des "sismomĂštres de pierre" peuvent ĂȘtre utilisĂ©s pour tĂ©moigner de cette sismicitĂ© passĂ©e qu'ils ont enregistrĂ©e dans leurs murs sous forme de dĂ©gĂąts ou de rĂ©parations. Je propose une mĂ©thodologie innovante reliant l'archĂ©ologie de la construction, la sismologie et le gĂ©nie sismique afin de dĂ©montrer que la caractĂ©risation archĂ©ologique des rĂ©parations post-sismiques sur les bĂątiments historiques peut permettre de dĂ©duire les principales caractĂ©ristiques du mouvement sismique. Cette mĂ©thodologie est dĂ©veloppĂ©e autour du cas de l'Ă©glise mĂ©diĂ©vale de Sant'Agata del Mugello, un site exceptionnel dont les dommages et les rĂ©parations induits par les sĂ©ismes sont dĂ©crits par de nombreuses sources historiques. Le site est situĂ© dans le bassin du Mugello (Apennin central, Italie, Toscane), caractĂ©risĂ© par une sismicitĂ© modĂ©rĂ©e. Les plus grands Ă©vĂ©nements connus se sont produits en 1542 (Mw ~ 6) et 1919 (Mw ~ 6.3). Nous commençons par retracer l'histoire sismique de l'Ă©glise en combinant une analyse stratigraphique du bĂątiment avec une Ă©tude approfondie des textes historiques. Un modĂšle de CAO est conçu Ă partir d'un relevĂ© gĂ©omĂ©trique issu d'une campagne de scanner laser. Un modĂšle de CAO de l'Ă©glise avant et aprĂšs chaque sĂ©isme historique est ensuite extrapolĂ© Ă partir du modĂšle de l'Ă©glise actuelle et de son histoire constructive. Un code de maillage ad hoc a Ă©tĂ© dĂ©veloppĂ© pour gĂ©nĂ©rer un maillage aux Ă©lĂ©ments finis Ă partir du modĂšle de CAO. Deux campagnes de vibrations ambiantes ont Ă©tĂ© menĂ©es dans l'Ă©glise de Sant'Agata. 8 modes de vibration (frĂ©quence propre, dĂ©formĂ©e modale et amortissement) sont estimĂ©s. Un processus d'optimisation des paramĂštres modaux, permet de calibrer le modĂšle numĂ©rique de l'Ă©glise dans sa partie linĂ©aire. Un modĂšle d'endommagement continu est utilisĂ© pour identifier la limite du modĂšle linĂ©aire de l'Ă©glise. Je me concentre ensuite sur l'Ă©tude du sĂ©isme historique de 1919 qui n'a pas causĂ© de dommages. Une collection de mouvements sismiques compatibles avec le contexte sismotectonique est sĂ©lectionnĂ©e, corrigĂ©e et est utilisĂ©e pour simuler le modĂšle numĂ©rique linĂ©aire calibrĂ© de l'Ă©glise. Je prĂ©sente des rĂ©sultats prĂ©liminaires pour discuter des caractĂ©ristiques du mouvement sismique associĂ© au sĂ©isme historique de 1919
De la caractĂ©risation du mouvement sismique associĂ© Ă des sĂ©ismes historiques. Etude de SantâAgata del Mugello en associant archĂ©ologie de la construction, gĂ©nie sismique et sismologie.
A fault is charged during (hundred-) thousand years, then the accumulated elastic energy is released in few secondswhen an earthquake occurs. To correctly assess seismic hazard it is of capital importance to study the seismic history.Over the last decades approaches such as historical seismology, archaeoseismology and paleoseismology have beendevelopped chasing alternative sources of information. Among them, historical buildings witnessed ancient earthquakesas âstone seismometersâ recorded in their walls as structural disorders and repairs. I develop an innovative methodologyconnecting building archaeology, seismology and earthquake engineering. I aim to show that archaeological characteri-zation of post-seismic repairs on historical buildings can successfully infer key ground motion characteristics of historicalearthquakes. The test case is the medieval church of SantâAgata del Mugello, an exceptional site with many historicalsources describing the damages induced by past earthquakes, and their renovation. The site is located in the Mugellobasin (Central Apennines, Italy, Tuscany), characterized by a moderate seismicity. The largest known events occurredin 1542 (Mw 6) and 1919 (Mw 6.3). I first trace the seismic history of the church by combing a stratigraphic analysisof the buidling with an in-depth study of historical texts. A CAD-based model of the current church is designed from alaser scanner survey. A CAD-model of the church before and after each historical earthquake is then extrapolated fromthe current church and its deduced constructive history. I have developed an ad hoc meshing code to generate a finiteelement mesh from the CAD-based model. We perform two ambient vibration testing survey in the church. 8 modes ofvibration (natural frequency, modal shapes and damping ratio) are estimated. A Vibration-Based model updating basedon the identified experimental parameters and the constructive history of the church allows to calibrate the numericalmodel of the church in its linear part. A continuum damage model is used to identify the limit of the linear model of thechurch. I then focus on the study of the 1919 non damaging earthquake. A collection of waveforms compatible with theseismotectonic context is selected, corrected, and used to solicit the updated linear digital model of the church. I showpreliminary results to discuss the ground motion characteristics of the 1919 earthquake.La dĂ©formation accumulĂ©e pendant plusieurs centaines (milliers) dâannĂ©es dans les zones de failles est brusquementrelĂąchĂ©e en seulement quelques secondes lorsquâun sĂ©isme se produit. LâĂ©tude des sĂ©ismes anciens Ă travers dif-fĂ©rentes Ă©chelles de temps est dâune importance capitale pour amĂ©liorer lâĂ©valuation de lâalĂ©a sismique. Au cours desderniĂšres dĂ©cennies des approches, telles que la sismologie historique, lâarchĂ©osismologie et la palĂ©osismologie ontĂ©tĂ© dĂ©veloppĂ©es pour chercher diverses sources dâinformations. Parmi elles, les bĂątiments historiques, tels des "sis-momĂštres de pierre" peuvent ĂȘtre utilisĂ©s pour tĂ©moigner de cette sismicitĂ© passĂ©e quâils ont enregistrĂ©e dans leursmurs sous forme de dĂ©gĂąts ou de rĂ©parations. Je propose une mĂ©thodologie innovante reliant lâarchĂ©ologie de la con-struction, la sismologie et le gĂ©nie sismique afin de dĂ©montrer que la caractĂ©risation archĂ©ologique des rĂ©parationspost-sismiques sur les bĂątiments historiques peut permettre de dĂ©duire les principales caractĂ©ristiques du mouvementsismique. Cette mĂ©thodologie est dĂ©veloppĂ©e autour du cas de lâĂ©glise mĂ©diĂ©vale de SantâAgata del Mugello, un siteexceptionnel dont les dommages et les rĂ©parations induits par les sĂ©ismes sont dĂ©crits par de nombreuses sourceshistoriques. Le site est situĂ© dans le bassin du Mugello (Apennin central, Italie, Toscane), caractĂ©risĂ© par une sismicitĂ©modĂ©rĂ©e. Les plus grands Ă©vĂ©nements connus se sont produits en 1542 (MwâŒ6) et 1919 (MwâŒ6.3). Nous commençonspar retracer lâhistoire sismique de lâĂ©glise en combinant une analyse stratigraphique du bĂątiment avec une Ă©tude appro-fondie des textes historiques. Un modĂšle de CAO est conçu Ă partir dâun relevĂ© gĂ©omĂ©trique issu dâune campagne descanner laser. Un modĂšle de CAO de lâĂ©glise avant et aprĂšs chaque sĂ©isme historique est ensuite extrapolĂ© Ă partir dumodĂšle de lâĂ©glise actuelle et de son histoire constructive. Un code de maillage ad hoc a Ă©tĂ© dĂ©veloppĂ© pour gĂ©nĂ©rerun maillage aux Ă©lĂ©ments finis Ă partir du modĂšle de CAO. Deux campagnes de vibrations ambiantes ont Ă©tĂ© menĂ©esdans lâĂ©glise de SantâAgata. 8 modes de vibration (frĂ©quence propre, dĂ©formĂ©e modale et amortissement) sont estimĂ©s.Un processus dâoptimisation des paramĂštres modaux, permet de calibrer le modĂšle numĂ©rique de lâĂ©glise dans sa partielinĂ©aire. Un modĂšle dâendommagement continu est utilisĂ© pour identifier la limite du modĂšle linĂ©aire de lâĂ©glise. Je meconcentre ensuite sur lâĂ©tude du sĂ©isme historique de 1919 qui nâa pas causĂ© de dommages. Une collection de mouve-ments sismiques compatibles avec le contexte sismotectonique est sĂ©lectionnĂ©e, corrigĂ©e et est utilisĂ©e pour solliciter lemodĂšle numĂ©rique linĂ©aire calibrĂ© de lâĂ©glise. Je prĂ©sente des rĂ©sultats prĂ©liminaires pour discuter des caractĂ©ristiquesdu mouvement sismique associĂ© au sĂ©isme historique de 1919
De la caractĂ©risation du mouvement sismique associĂ© Ă des sĂ©ismes historiques : Ă©tude de SantâAgata del Mugello en associant archĂ©ologie de la construction, gĂ©nie sismique et sismologie
A fault is charged during (hundred-) thousand years, then the accumulated elastic energy is released in few seconds when an earthquake occurs. To correctly assess seismic hazard it is of capital importance to study the seismic history. Over the last decades alternative approaches such as historical seismology, archaeoseismology and paleoseismology have been developped chasing alternative sources of information. Among them, historical buildings witnessed ancient earthquakes as âstone seismometersâ recorded in their walls as structural disorders and repairs. I develop an innovative methodology connecting building archaeology, seismology and earthquake engineering. I aim to show that archaeological characterization of post-seismic repairs on historical buildings can successfully infer key ground motion characteristics of historical earthquakes. The test case is the medieval church of SantâAgata del Mugello, an exceptional site with many historical sources describing the damages induced by past earthquakes, and their renovation. The site is located in the Mugello basin (Central Apennines, Italy, Tuscany), characterized by a moderate seismicity. The largest known events occurred in 1542 (Mw~6) and 1919 (Mw~6.3). I first trace the seismic history of the church by combing a stratigraphic analysis of the buidling with an in-depth study of historical texts. A CAD-based model of the current church is designed from a laser scanner survey. A CAD-model of the church before and after each historical earthquake is then extrapolated from the current church and its deduced constructive history. I have developed an textit{ad hoc} meshing code to generate a finite element mesh from the CAD-based model. We perform two ambient vibration testing surveys in the church. 8 modes of vibration (natural frequency, modal shapes and damping ratio) are estimated. A Vibration-Based model updating based on the identified experimental parameters and the constructive history of the church allows to calibrate the numerical model of the church in its linear part. A continuum damage model is used to identify the limit of the linear model of the church. I then focus on the study of the 1919 non damaging earthquake. A collection of waveforms compatible with the seismotectonic context is selected, corrected, and used to simulate the updated linear digital model of the church. I show preliminary results to discuss the ground motion characteristics of the 1919 earthquake.La dĂ©formation accumulĂ©e pendant plusieurs centaines (milliers) d'annĂ©es dans les zones de failles est brusquement relĂąchĂ©e en seulement quelques secondes lorsqu'un sĂ©isme se produit. L'Ă©tude des sĂ©ismes anciens Ă travers diffĂ©rentes Ă©chelles de temps est d'une importance capitale pour amĂ©liorer l'Ă©valuation de l'alĂ©a sismique. Au cours des derniĂšres dĂ©cennies des approches alternatives, telles que la sismologie historique, l'archĂ©osismologie et la palĂ©osismologie ont Ă©tĂ© dĂ©veloppĂ©es pour chercher des sources d'informations. Parmi elles, les bĂątiments historiques, tels des "sismomĂštres de pierre" peuvent ĂȘtre utilisĂ©s pour tĂ©moigner de cette sismicitĂ© passĂ©e qu'ils ont enregistrĂ©e dans leurs murs sous forme de dĂ©gĂąts ou de rĂ©parations. Je propose une mĂ©thodologie innovante reliant l'archĂ©ologie de la construction, la sismologie et le gĂ©nie sismique afin de dĂ©montrer que la caractĂ©risation archĂ©ologique des rĂ©parations post-sismiques sur les bĂątiments historiques peut permettre de dĂ©duire les principales caractĂ©ristiques du mouvement sismique. Cette mĂ©thodologie est dĂ©veloppĂ©e autour du cas de l'Ă©glise mĂ©diĂ©vale de Sant'Agata del Mugello, un site exceptionnel dont les dommages et les rĂ©parations induits par les sĂ©ismes sont dĂ©crits par de nombreuses sources historiques. Le site est situĂ© dans le bassin du Mugello (Apennin central, Italie, Toscane), caractĂ©risĂ© par une sismicitĂ© modĂ©rĂ©e. Les plus grands Ă©vĂ©nements connus se sont produits en 1542 (Mw ~ 6) et 1919 (Mw ~ 6.3). Nous commençons par retracer l'histoire sismique de l'Ă©glise en combinant une analyse stratigraphique du bĂątiment avec une Ă©tude approfondie des textes historiques. Un modĂšle de CAO est conçu Ă partir d'un relevĂ© gĂ©omĂ©trique issu d'une campagne de scanner laser. Un modĂšle de CAO de l'Ă©glise avant et aprĂšs chaque sĂ©isme historique est ensuite extrapolĂ© Ă partir du modĂšle de l'Ă©glise actuelle et de son histoire constructive. Un code de maillage ad hoc a Ă©tĂ© dĂ©veloppĂ© pour gĂ©nĂ©rer un maillage aux Ă©lĂ©ments finis Ă partir du modĂšle de CAO. Deux campagnes de vibrations ambiantes ont Ă©tĂ© menĂ©es dans l'Ă©glise de Sant'Agata. 8 modes de vibration (frĂ©quence propre, dĂ©formĂ©e modale et amortissement) sont estimĂ©s. Un processus d'optimisation des paramĂštres modaux, permet de calibrer le modĂšle numĂ©rique de l'Ă©glise dans sa partie linĂ©aire. Un modĂšle d'endommagement continu est utilisĂ© pour identifier la limite du modĂšle linĂ©aire de l'Ă©glise. Je me concentre ensuite sur l'Ă©tude du sĂ©isme historique de 1919 qui n'a pas causĂ© de dommages. Une collection de mouvements sismiques compatibles avec le contexte sismotectonique est sĂ©lectionnĂ©e, corrigĂ©e et est utilisĂ©e pour simuler le modĂšle numĂ©rique linĂ©aire calibrĂ© de l'Ă©glise. Je prĂ©sente des rĂ©sultats prĂ©liminaires pour discuter des caractĂ©ristiques du mouvement sismique associĂ© au sĂ©isme historique de 1919
De la caractĂ©risation du mouvement sismique associĂ© Ă des sĂ©ismes historiques. Etude de SantâAgata del Mugello en associant archĂ©ologie de la construction, gĂ©nie sismique et sismologie.
A fault is charged during (hundred-) thousand years, then the accumulated elastic energy is released in few secondswhen an earthquake occurs. To correctly assess seismic hazard it is of capital importance to study the seismic history.Over the last decades approaches such as historical seismology, archaeoseismology and paleoseismology have beendevelopped chasing alternative sources of information. Among them, historical buildings witnessed ancient earthquakesas âstone seismometersâ recorded in their walls as structural disorders and repairs. I develop an innovative methodologyconnecting building archaeology, seismology and earthquake engineering. I aim to show that archaeological characteri-zation of post-seismic repairs on historical buildings can successfully infer key ground motion characteristics of historicalearthquakes. The test case is the medieval church of SantâAgata del Mugello, an exceptional site with many historicalsources describing the damages induced by past earthquakes, and their renovation. The site is located in the Mugellobasin (Central Apennines, Italy, Tuscany), characterized by a moderate seismicity. The largest known events occurredin 1542 (Mw 6) and 1919 (Mw 6.3). I first trace the seismic history of the church by combing a stratigraphic analysisof the buidling with an in-depth study of historical texts. A CAD-based model of the current church is designed from alaser scanner survey. A CAD-model of the church before and after each historical earthquake is then extrapolated fromthe current church and its deduced constructive history. I have developed an ad hoc meshing code to generate a finiteelement mesh from the CAD-based model. We perform two ambient vibration testing survey in the church. 8 modes ofvibration (natural frequency, modal shapes and damping ratio) are estimated. A Vibration-Based model updating basedon the identified experimental parameters and the constructive history of the church allows to calibrate the numericalmodel of the church in its linear part. A continuum damage model is used to identify the limit of the linear model of thechurch. I then focus on the study of the 1919 non damaging earthquake. A collection of waveforms compatible with theseismotectonic context is selected, corrected, and used to solicit the updated linear digital model of the church. I showpreliminary results to discuss the ground motion characteristics of the 1919 earthquake.La dĂ©formation accumulĂ©e pendant plusieurs centaines (milliers) dâannĂ©es dans les zones de failles est brusquementrelĂąchĂ©e en seulement quelques secondes lorsquâun sĂ©isme se produit. LâĂ©tude des sĂ©ismes anciens Ă travers dif-fĂ©rentes Ă©chelles de temps est dâune importance capitale pour amĂ©liorer lâĂ©valuation de lâalĂ©a sismique. Au cours desderniĂšres dĂ©cennies des approches, telles que la sismologie historique, lâarchĂ©osismologie et la palĂ©osismologie ontĂ©tĂ© dĂ©veloppĂ©es pour chercher diverses sources dâinformations. Parmi elles, les bĂątiments historiques, tels des "sis-momĂštres de pierre" peuvent ĂȘtre utilisĂ©s pour tĂ©moigner de cette sismicitĂ© passĂ©e quâils ont enregistrĂ©e dans leursmurs sous forme de dĂ©gĂąts ou de rĂ©parations. Je propose une mĂ©thodologie innovante reliant lâarchĂ©ologie de la con-struction, la sismologie et le gĂ©nie sismique afin de dĂ©montrer que la caractĂ©risation archĂ©ologique des rĂ©parationspost-sismiques sur les bĂątiments historiques peut permettre de dĂ©duire les principales caractĂ©ristiques du mouvementsismique. Cette mĂ©thodologie est dĂ©veloppĂ©e autour du cas de lâĂ©glise mĂ©diĂ©vale de SantâAgata del Mugello, un siteexceptionnel dont les dommages et les rĂ©parations induits par les sĂ©ismes sont dĂ©crits par de nombreuses sourceshistoriques. Le site est situĂ© dans le bassin du Mugello (Apennin central, Italie, Toscane), caractĂ©risĂ© par une sismicitĂ©modĂ©rĂ©e. Les plus grands Ă©vĂ©nements connus se sont produits en 1542 (MwâŒ6) et 1919 (MwâŒ6.3). Nous commençonspar retracer lâhistoire sismique de lâĂ©glise en combinant une analyse stratigraphique du bĂątiment avec une Ă©tude appro-fondie des textes historiques. Un modĂšle de CAO est conçu Ă partir dâun relevĂ© gĂ©omĂ©trique issu dâune campagne descanner laser. Un modĂšle de CAO de lâĂ©glise avant et aprĂšs chaque sĂ©isme historique est ensuite extrapolĂ© Ă partir dumodĂšle de lâĂ©glise actuelle et de son histoire constructive. Un code de maillage ad hoc a Ă©tĂ© dĂ©veloppĂ© pour gĂ©nĂ©rerun maillage aux Ă©lĂ©ments finis Ă partir du modĂšle de CAO. Deux campagnes de vibrations ambiantes ont Ă©tĂ© menĂ©esdans lâĂ©glise de SantâAgata. 8 modes de vibration (frĂ©quence propre, dĂ©formĂ©e modale et amortissement) sont estimĂ©s.Un processus dâoptimisation des paramĂštres modaux, permet de calibrer le modĂšle numĂ©rique de lâĂ©glise dans sa partielinĂ©aire. Un modĂšle dâendommagement continu est utilisĂ© pour identifier la limite du modĂšle linĂ©aire de lâĂ©glise. Je meconcentre ensuite sur lâĂ©tude du sĂ©isme historique de 1919 qui nâa pas causĂ© de dommages. Une collection de mouve-ments sismiques compatibles avec le contexte sismotectonique est sĂ©lectionnĂ©e, corrigĂ©e et est utilisĂ©e pour solliciter lemodĂšle numĂ©rique linĂ©aire calibrĂ© de lâĂ©glise. Je prĂ©sente des rĂ©sultats prĂ©liminaires pour discuter des caractĂ©ristiquesdu mouvement sismique associĂ© au sĂ©isme historique de 1919
Rectangular blocks vs polygonal walls in archaeoseismology
Collapsed or deformed walls in ancient structures constitute important evidence in archaeoseismology, where damage is interpreted in terms of earthquake ground motion. A large variety of wall types have been developed during the millennia in different cultural backgrounds. Often walls with polygonal-shaped building blocks are regarded as more earthquake-resistant than a wall consisting of rectangular elements and, as is sometimes speculated, that the irregular wall types were intentionally developed for that purpose. We use simply structured discrete element models of four walls with different block geometries, perfect rectangular, an Inca-type structure and two polygonal designs, to test their dynamic behavior. In addition to an analytic calculation of ground motion, we use measured strong motion signals as boundary conditions for the 3D wall models with varying height to width ratios. At peak ground accelerations between 1.0 and 9.0 m/s(2) and major frequencies of 0.5 to 3 Hz, numeric experiments with the horizontally applied analytic ground motions result in clear differences in the resistance of the four wall types with the rectangular block wall being most vulnerable. For more complex measured 3D motions the Inca-type wall proves more stable than the rectangular block wall; however, height to width ratio still has equally strong influence on the stability. Internal deformation of non-collapsed walls shows some correlation with the parameters of the driving motion. For simple impulsive ground motions, a peak ground displacement threshold exists between toppling and remaining upright for all four models but peak acceleration cannot be reliably back calculated
Mettre en évidence l'impact de l'histoire de la construction d'un bùtiment du patrimoine culturel grùce à un modÚle aux éléments finis calibré à partir de mesures vibratoires via une une optimisation par essaims particulaires
International audienceNumerical models play a primary role in Cultural Heritage preservation. Nevertheless, the design of a realistic model remains challenging due not only to the complex behavior of masonry but also to the asynchronous building phases, the damage induced by natural and anthropic aggression, and the associated repairs. This paper discusses the impact of the information provided by an in-depth analysis of the construction history on the updating process of a Finite Element building model. The case study is the church of Sant'Agata del Mugello (Italy); for this building, a previous historical-archaeological study identified and recorded the asynchronous construction phases, the repair techniques, and the damage induced by three historical earthquakes (1542, 1611, and 1919)âmoreover, a dense ambient vibration survey allowed to identify the modal parameters. The information from previous works is summarized in five Finite Element models with increasing complexity. A vibration-based model updating methodology based on a Particle Swarm Algorithm is developed. This work shows that the best minimization of the difference between the numerical and experimental modal parameters is obtained with the numerical model considering the identified construction techniques, repair phases, and connection relations between the bell tower and the nave
High resolution operational modal analysis of SantâAgata del Mugello in light of its building history
International audienceThe building history of a cultural heritage building and the after-effects induced by extreme loads such as earthquakes have a durable impact on its modal parameters. This article aims to discuss the peculiarities of some modal parameters extracted from ambient vibration measurements in light of the complex history of SantâAgata del Mugello. The Romanesque church located in the Mugello basin (Tuscany, Italy) suffered from many earthquakes, at least from 1542. In this context, we carried out two dense ambient vibration campaigns in March and June 2019. We extracted each modeâs natural frequency, mode shape, and damping using the Enhanced Frequency Domain Decomposition. We identified ten modes. Some modes highlight structural singularities related to the building history of the church: rocking of the base of the bell tower; phase opposition between the bell tower and the nave; bending of the walls of the nave. Since the instrumentation benefited from a vast number of recording positions (83), we tested the impact of the sensor placement strategy on the resolution of the identified modal parameters in the specific case of SantâAgata del Mugello. The resolution of the higher-order modes decreases strongly in case of degraded sensor placement strategy impacting the dynamic analysis of the church
Tracing the seismic history of SantâAgata del Mugello (Italy, Tuscany) through a cross-disciplinary approach
International audienceHistorical seismicity is mainly defined from historical sources which are not always available. Yet historical buildings are a unique opportunity to record and study effects of past earthquakes at a given place. An innovative methodology is defined to improve knowledge of local historical seismicity. Such a methodology is based on an interdisciplinary approach combining: analysis of historical sources, stratigraphic analysis and structural analysis of an historical building. The church of SantâAgata del Mugello (Italy, Tuscany) is considered as a case of study. The stratigraphic analysis is performed by identifying the repairs using the RECAP methodology. 80 repairs units using 13 building techniques are identified in the church. The identified repairs are associated with unknown events, earthquakes or routine reconstructions. When post-earthquake reconstructions are found, damage mechanisms are associated with them. 13 constructive phases of the church have been traced combining stratigraphic analysis and historical sources. A proto-church was built before 948 A.D. and is nowadays below the current one. The first phase of the current church appears between the 9th and the 12th century. A significant event of unknown origin occurred during the 12th century which probably led to an important collapse and then a significant reconstruction of the church. The church is then deeply affected by the 1542 seismic event (epicentral macroseismic intensity 9, deduced magnitude 6.02) which resulted in the collapse of the upper part of the bell tower and the two lateral chapels as well as the overturning of the front wall and of the two lateral walls of the nave. The 1611 seismic event (epicentral macroseismic intensity 7, deduced magnitude 5.1) damaged the upper part of the bell tower as described in historical records. In spite of the confirmed occurrence of seismic events in the area from the middle of the 17th century and the beginning of the 20th century, no information relating seismic damage of the church has been found in historical records nor in the startigraphic analysis. The most important earthquake which struck the area on June 19th, 1919, produced only some small cracks in the church (magnitude 6.38)
An Open Database to Evaluate the Fundamental Frequency of Historical Masonry Towers through Empirical and Physics-Based Formulations
International audienceThe fundamental frequency plays a primary role in the dynamic assessment of Cultural Heritage towers. Local and global features may impact its value: geometric, material features, interaction with the soil and adjacent buildings, aging, the construction phase, and repairs. A database is assembled to study the relationship between the fundamental frequency and the slender masonry structure features. Empirical and physics-based approaches were developed to assess the fundamental frequency from different sources of information. A RayleighâRitz approach is proposed and compared with a 3D finite element model. A sensitivity analysis is then performed to quantify the contribution of each feature. As expected, it is shown that the height of the tower contributes the most to the fundamental frequency. The other tower features have a second-order impact on both the fundamental frequency and the mode shape. A comparison between the different approaches shows that the RayleighâRitz drastically minimizes the difference between numerical and experimental frequencies when all information is available. Empirical relations are a good compromise when less information is available