Pub Date : 2021-01-01DOI: 10.7712/120121.8594.18712
M. Scalvenzi, F. Freddi, F. Parisi
Most of the existing buildings in seismic prone regions have been built before the publication of modern design provisions against seismic events and progressive collapse. Nonetheless, some studies have highlighted the possible interaction between earthquake resistance and structural robustness, the latter being of interest to either individual extreme hazards (e.g., blast, impact, fire) or interacting hazards (e.g., landslides produced by seismic events). While retrofit strategies to improve the seismic performance of reinforced concrete (RC) structures have been widely investigated since many years, the topic of mitigation strategies against progressive collapse received very little attention. Progressive collapse can be described as a special type of structural collapse that involves several components of the structure as consequence of an initial localised damage. The present study aims at investigating whether and how much seismic retrofitting may improve not only the earthquake resistance but also robustness. A four-storey, five-bay, RC frame building designed according to Eurocode 2 is considered as a case study. The frame was assessed by evaluating: 1) the capacity of the structure to redistribute loads after a local damaging event; 2) the seismic capacity of the structure. Non-linear static analyses, i.e., PushDown and PushOver analyses, were carried out in OpenSees to evaluate the robustness and seismic resistance of the structure, respectively. The progressive collapse capacity was evaluated under two relevant column-removal scenarios, i.e., the sudden loss of an internal and an external column, while the seismic resistance was assessed under two load distributions, i.e., proportional to the first vibration mode and to the inertia masses. Subsequently, the impact of retrofitting with carbon fibre-reinforced polymers on both structural robustness and seismic resistance was evaluated. The use of the retrofit measure allowed, on the one hand, the removal of all the shear failures due to horizontal seismic actions and, on the other hand, to increase the robustness of the structure.
{"title":"ASSESSMENT AND RETROFITTING OF A RC BUILDING THROUGH A MULTI-HAZARD APPROACH: SEISMIC RESISTANCE AND ROBUSTNESS","authors":"M. Scalvenzi, F. Freddi, F. Parisi","doi":"10.7712/120121.8594.18712","DOIUrl":"https://doi.org/10.7712/120121.8594.18712","url":null,"abstract":"Most of the existing buildings in seismic prone regions have been built before the publication of modern design provisions against seismic events and progressive collapse. Nonetheless, some studies have highlighted the possible interaction between earthquake resistance and structural robustness, the latter being of interest to either individual extreme hazards (e.g., blast, impact, fire) or interacting hazards (e.g., landslides produced by seismic events). While retrofit strategies to improve the seismic performance of reinforced concrete (RC) structures have been widely investigated since many years, the topic of mitigation strategies against progressive collapse received very little attention. Progressive collapse can be described as a special type of structural collapse that involves several components of the structure as consequence of an initial localised damage. The present study aims at investigating whether and how much seismic retrofitting may improve not only the earthquake resistance but also robustness. A four-storey, five-bay, RC frame building designed according to Eurocode 2 is considered as a case study. The frame was assessed by evaluating: 1) the capacity of the structure to redistribute loads after a local damaging event; 2) the seismic capacity of the structure. Non-linear static analyses, i.e., PushDown and PushOver analyses, were carried out in OpenSees to evaluate the robustness and seismic resistance of the structure, respectively. The progressive collapse capacity was evaluated under two relevant column-removal scenarios, i.e., the sudden loss of an internal and an external column, while the seismic resistance was assessed under two load distributions, i.e., proportional to the first vibration mode and to the inertia masses. Subsequently, the impact of retrofitting with carbon fibre-reinforced polymers on both structural robustness and seismic resistance was evaluated. The use of the retrofit measure allowed, on the one hand, the removal of all the shear failures due to horizontal seismic actions and, on the other hand, to increase the robustness of the structure.","PeriodicalId":66281,"journal":{"name":"地震工程与工程振动","volume":"55 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77441209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.7712/120121.8862.18870
Nicolas Ombret, Maxime de Pret, A. Dugeai, F. Thouverez, L. Blanc, T. Berthelon
. Fan Blade Flutter is an aeroelastic instability which may occur during the operation of a jet engine, depending on the working conditions of the fan stage. It finds its origins in some various mechanisms, including the impact of the environment of the fan stage, which may play an important role in the stability limits due to acoustic effects. If not properly taken into account, flutter can lead to an anticipated ruin of the fan stage as the fluid keeps on giving energy to the structure. However, nonlinear phenomena may appear at some high vibratory amplitude of the blades, resulting in energy dissipation of the aeroelastic system. Blade roots friction is an example of such a case : by dry-friction dissipation at blade roots, a limitation of the vibratory amplitude may be reached, the so-called Limit Cycle Oscillations (LCO), within the unstable regions of the operating domain predicted with a usual linear structural modelling. By taking these nonlinear effects into account, it is then possible to define more precisely the stability limits of the fan stage. In this paper, we describe a methodology to predict LCO induced by blade roots friction, including acoustic effects on stability. First, assuming a linear behaviour of the structure
{"title":"INVESTIGATION OF A METHODOLOGY FOR DESCRIBING FAN BLADE FLUTTER LIMITATIONS INDUCED BY NON-LINEAR FRICTION AT BLADE ROOTS","authors":"Nicolas Ombret, Maxime de Pret, A. Dugeai, F. Thouverez, L. Blanc, T. Berthelon","doi":"10.7712/120121.8862.18870","DOIUrl":"https://doi.org/10.7712/120121.8862.18870","url":null,"abstract":". Fan Blade Flutter is an aeroelastic instability which may occur during the operation of a jet engine, depending on the working conditions of the fan stage. It finds its origins in some various mechanisms, including the impact of the environment of the fan stage, which may play an important role in the stability limits due to acoustic effects. If not properly taken into account, flutter can lead to an anticipated ruin of the fan stage as the fluid keeps on giving energy to the structure. However, nonlinear phenomena may appear at some high vibratory amplitude of the blades, resulting in energy dissipation of the aeroelastic system. Blade roots friction is an example of such a case : by dry-friction dissipation at blade roots, a limitation of the vibratory amplitude may be reached, the so-called Limit Cycle Oscillations (LCO), within the unstable regions of the operating domain predicted with a usual linear structural modelling. By taking these nonlinear effects into account, it is then possible to define more precisely the stability limits of the fan stage. In this paper, we describe a methodology to predict LCO induced by blade roots friction, including acoustic effects on stability. First, assuming a linear behaviour of the structure","PeriodicalId":66281,"journal":{"name":"地震工程与工程振动","volume":"56 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78152341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.7712/120121.8745.19101
G. Maddaloni, A. Angelis, Francesco Minicozzi, Claudio Martino, M. Pecce
{"title":"DEVELOPMENT OF LOW COST SENSORS FOR MONITORING OF STRUCTURES","authors":"G. Maddaloni, A. Angelis, Francesco Minicozzi, Claudio Martino, M. Pecce","doi":"10.7712/120121.8745.19101","DOIUrl":"https://doi.org/10.7712/120121.8745.19101","url":null,"abstract":"","PeriodicalId":66281,"journal":{"name":"地震工程与工程振动","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80410208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.7712/120121.8673.19021
G. Manos, N. Simos
{"title":"STUDYING THE PERFORMANCE OF STONE MASONRY ARCH BRIDGES EMPLOYING IN-SITU MEASUREMENTS AND NUMERICAL PREDICTIONS","authors":"G. Manos, N. Simos","doi":"10.7712/120121.8673.19021","DOIUrl":"https://doi.org/10.7712/120121.8673.19021","url":null,"abstract":"","PeriodicalId":66281,"journal":{"name":"地震工程与工程振动","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80526558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.7712/120121.8837.18888
K. Morfidis
{"title":"GENERELIZED MACROELEMENT FOR GEOMETRIC AND MATERIALLY NON-LINEAR ANALYSIS OF STEEL MEMBERS","authors":"K. Morfidis","doi":"10.7712/120121.8837.18888","DOIUrl":"https://doi.org/10.7712/120121.8837.18888","url":null,"abstract":"","PeriodicalId":66281,"journal":{"name":"地震工程与工程振动","volume":"60 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84164788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.7712/120121.8768.19307
J. Ghosh, F. Freddi
Damage incurred in low-ductility reinforced concrete (RC) buildings during recent earthquakes continues to underline their structural vulnerability under seismic shaking. Among the viable seismic retrofitting procedures, passive control systems such as buckling-restrained braces (BRBs) have emerged as an efficient strategy for structural damage mitigation through stable energy dissipation while providing additional strength and stiffness to low-ductility buildings. Although quantifying the beneficial effects of BRBs for vulnerability reduction through seismic fragility curves has been suitably investigated in literature, almost all such studies consider a deterministic description of the BRB device. This study illustrates a metamodeling framework rooted in statistical learning techniques for efficient seismic vulnerability assessment of BRB-retrofitted low-ductility RC frames. The framework develops multidimensional probabilistic seismic demand models for response prediction of a case study retrofitted frames as a function of ground motion characteristics as well as the design parameters of the BRB device. These demand models when compared against damage states capacity estimates subsequently yields vector-based seismic fragility functions that provide notable advantages over unidimensional fragility curves in terms of efficiency as well as generality. Additionally, uncertainties stemming from a multitude of sources can also be conveniently captured and propagated through the different stages of statistical model development. The proposed study aims to help researchers, stakeholders, and even device manufactures by providing a conven-ient tool for vulnerability evaluation of retrofitted structures with reasonable accuracy and enhanced efficiency of computation. Concrete Frames, Seismic Retrofit, Seismic Devices Uncertainty, Metamodeling.
{"title":"METAMODELING CHOICES FOR SEISMIC VULNERABILITY ASSESSMENT OF BRB-RETROFITTED LOW-DUCTILITY RC FRAMES","authors":"J. Ghosh, F. Freddi","doi":"10.7712/120121.8768.19307","DOIUrl":"https://doi.org/10.7712/120121.8768.19307","url":null,"abstract":"Damage incurred in low-ductility reinforced concrete (RC) buildings during recent earthquakes continues to underline their structural vulnerability under seismic shaking. Among the viable seismic retrofitting procedures, passive control systems such as buckling-restrained braces (BRBs) have emerged as an efficient strategy for structural damage mitigation through stable energy dissipation while providing additional strength and stiffness to low-ductility buildings. Although quantifying the beneficial effects of BRBs for vulnerability reduction through seismic fragility curves has been suitably investigated in literature, almost all such studies consider a deterministic description of the BRB device. This study illustrates a metamodeling framework rooted in statistical learning techniques for efficient seismic vulnerability assessment of BRB-retrofitted low-ductility RC frames. The framework develops multidimensional probabilistic seismic demand models for response prediction of a case study retrofitted frames as a function of ground motion characteristics as well as the design parameters of the BRB device. These demand models when compared against damage states capacity estimates subsequently yields vector-based seismic fragility functions that provide notable advantages over unidimensional fragility curves in terms of efficiency as well as generality. Additionally, uncertainties stemming from a multitude of sources can also be conveniently captured and propagated through the different stages of statistical model development. The proposed study aims to help researchers, stakeholders, and even device manufactures by providing a conven-ient tool for vulnerability evaluation of retrofitted structures with reasonable accuracy and enhanced efficiency of computation. Concrete Frames, Seismic Retrofit, Seismic Devices Uncertainty, Metamodeling.","PeriodicalId":66281,"journal":{"name":"地震工程与工程振动","volume":"64 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84578570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.7712/120121.8739.19562
M. Iovino, Emmanouil Rovithis, R. Di Laora, Cristiano D'Alterio, L. de Sanctis, T. K. Garala, S. Haigh, G. Madabhushi
{"title":"ASPECTS OF SEISMIC SOIL-PILE-STRUCTURE INTERACTION IN SOFT CLAY BY CENTRIFUGE TESTING","authors":"M. Iovino, Emmanouil Rovithis, R. Di Laora, Cristiano D'Alterio, L. de Sanctis, T. K. Garala, S. Haigh, G. Madabhushi","doi":"10.7712/120121.8739.19562","DOIUrl":"https://doi.org/10.7712/120121.8739.19562","url":null,"abstract":"","PeriodicalId":66281,"journal":{"name":"地震工程与工程振动","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80917599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.7712/120121.8847.18976
P. Reumers, G. Lombaert, G. Degrande
{"title":"FREE VIBRATION RESPONSE OF LONG MULTI-SPAN BRIDGES ACCOUNTING FOR SOIL-STRUCTURE INTERACTION","authors":"P. Reumers, G. Lombaert, G. Degrande","doi":"10.7712/120121.8847.18976","DOIUrl":"https://doi.org/10.7712/120121.8847.18976","url":null,"abstract":"","PeriodicalId":66281,"journal":{"name":"地震工程与工程振动","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81095479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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