Browsing by Author "Rovero, Luisa"

Now showing 1 - 7 of 7
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    A new method for assessing compatibility of consolodation procedures with conservation principles: Intervention Qualitiy Index
    Llera Martin, Juan Carlos de la; Palazzi, Nuria Chiara; Misseri, Giulia; Sandoval, Cristián; Tonietti, Ugo; Rovero, Luisa
    In current times, built heritage is being lost at an alarming rate due to natural and human hazards. Policies for its protection and rehabilitation involve, among other things, challenges related to the refinement of suitable structural strengthening approaches. The arduous balance between gaining acceptable safety levels for occupants without deploying intrusive devices, inconsistent with conservation principles such as those of the ICOMOS charters, is not a simple task. The interest and efforts of the scientific community in this regard have been increasing for decades, but still, it is the structural professional´s responsibility and experience which must define this arduous balance on a case-to-case basis. This study addresses the question: How can the quality of structural rehabilitation interventions be assessed in light of conservation principles such as those given by ICOMOS? Here, a preliminary method - called “Intervention Quality Index” (IQI) method is proposed. It assesses the restoration intervention quality in relation to: (i) the level of compliance given by the conservation´s principle score (conservation´s factor, CF); and (ii) the current state of conservation of the monument (safety factor of building considering the seismic intensity, Δs). The IQI method considers the compliance level of the designed reinforcement with conservation principle, formalized through the fulfillment of a category, i.e. respected, partially respected, and not respected. Then, these judgments are translated into scores and statistically evaluated. Scores are attributed in relation to the relevance of the fulfillment of a certain conservation principle (authenticity, minimal intervention and intrusiveness, compatibility, recognizability and reversibility) for the seismic structural safety point of view. Preliminary results show that an effective employment of traditional earthquake-resistant practices together with a wise use of modern retrofit strategies allow for the preservation and reinforcement of built heritage without harming its identity
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    Kinematic limit analysis of Basilica del Salvador, a significant example of the neo-gothic architecture in Santiago, Chile
    Palazzi Chiara, Nuria; Rovero, Luisa; Tonietti, Hugo; Llera Martin, Juan Carlos de la; Sandoval Mandujano, Cristián
    The Basilica del Salvador, located in Santiago city, is one of the most significant examples of the Chilean Neogothic architecture. Its current state of damage shows several local collapses caused by the March 3rd, 1985 central Chile earthquake, and the February 27th, 2010 Maule earthquake. As part of an ongoing research, this paper investigates the seismic behaviour of the church through the kinematic limit analyses. For this purpose, the main collapse mechanisms have been identified and analyzed. The results show that the seismic response is unsatisfactory and shows the inadequacy of the seismic performance of this constructional typology in a highly seismic context, due to the extremely slenderness of the structural elements and to the absence of box-behaviour, making it particularly sensitive to earthquake loading. It should be noted that these preliminary results are part of an ongoing research about the seismic retrofit of Basilica del Salvador.
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    Seismic damage and fragility assessment of ancient masonry churches located in central Chile
    (2020) Palazzi Chiara, Nuria; Favier, Philomène; Rovero, Luisa; Sandoval Mandujano, Cristián; Llera Martin, Juan Carlos de la
    An assessment of damage and seismic fragility of historical unreinforced masonry churches located in Chile’s central valley was carried out employing the results of a field survey of 106 ancient churches, after the 2010 Maule earthquake. The observed damage was correlated with recurrent failure mechanisms of unreinforced masonry structures, by taking into account 22 local mechanisms involving macro-elements on these churches. The average damage level suffered by each church was computed considering the global and local behaviors of the structures through a damage index computed as a weighted mean of the levels of damage observed for each mechanism. The results of this damage index method are used to obtain Probability Mass Functions and suitable probabilistic tools are used to propose Empirical Fragility Curves (EFCs) for these structures. The EFCs are directly usable by stakeholders involved in risk assessment aimed to the prioritization of possible future damage mitigation strategies and other decision making processes relative to this historical heritage.
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    Seismic fragility assessment of unreinforced masonry churches of central Chile.
    (2019) Palazzi Chiara, Nuria; Llera Martin, Juan Carlos de la; Rovero, Luisa; Pontificia Universidad Católica de Chile. Escuela de Ingeniería
    The present thesis focuses on the seismic fragility assessment of unreinforced masonry (URM) churches in central Chile. The intrinsic value of this built heritage is due to its original features, synthesis of local and European architectural cultures. Due to the structural weaknesses of URM monuments, Chile‘s high seismic hazard, the absence of design standards and guidelines, and the ineffective performance of recently implemented retrofits, this built heritage is at-risk. For these reasons, the broad scope of this study is to document, for the first time, an essential part of the heritage asset of Chile, and to highlight principal vulnerabilities through a proper safety assessment framework, with the aim to promote conservation policies compatible with heritage identity and meeting new safety requirements. Historical, typological and technological features of the selected churches, consisting of 106 churches, are outlined and consistent categories are formed. Churches of each class share stylistic and technological characteristics, but also and more importantly, the same structural weaknesses. Within this framework, two scales are adopted to investigate the seismic performance of these monuments: territorial and building. At territorial-scale, the selected 106 churches are organized in a database that collects essential information for fragility assessment and damage forecasting (e.g. expected 2010 Maule PGA, architectural, typological, and material parameters). As a result, the main variables that control the seismic fragility of these structures were determined. The main outcome obtained downstream from this survey is related the damage suffered by the entire stock following the 2010 (8.8Mw) Maule earthquake. The matrix of plots for the frequency distributions of the selected variables and damage level frequency diagrams enabled the identification of the following three homogeneous classes. These are: Colonial (CL), Neo-classical & Variant (NC&V) and Neo-gothic (NG). Probability Mass Functions (PMFs)and Empirical Fragility Curves (EFCs) have been obtained using validated models such as a lognormal distribution fitted by least squares, and a generalized linear model function fitted by maximum likelihood estimation. At building-scale, three case studies representative of fragility classes are identified. These churches are: San Francisco in Santiago, San Judas in Malloa, and San Salvador in Santiago. A methodology to assess the seismic performance of these URM structures is provided, and the seismic response and risk quantified. Finally, a new procedure is proposed to evaluate arbitrary structural retrofit interventions in view of more general ICOMOS principles. For each intervention, a conformity level in terms of alignment with conservation principles has been assessed. This methodology has been applied to evaluate the retrofit interventions proposed or implemented to reinforce the three selected case studies. This thesis provides useful predictive tools for seismic risk reduction plans of churches, which is directly usable as a framework to be employed by stakeholders and safety related decisionmakers. Moreover, the main findings can be exported to all those contexts in which European architectural revivalisms have influenced local building techniques (e.g. Central and Southern America).
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    Seismic Vulnerability Assessment of a 17th Century Colonial Adobe Church in the Central Valley of Chile
    (2020) Palazzi Chiara, Nuria; Misseri, Giulia; Rovero, Luisa; Llera Martin, Juan Carlos de la
    This paper focuses on the seismic vulnerability assessment of the San Judas Tadeo´s church in Malloa (Chile), an iconic example of Colonial Chilean architecture. This small adobe structure is a single-nave building consisting of the nave, a bell-tower located in the façade, two external wooden galleries and a number of additional units such as the sacristy, chapel, and two services areas. The Church has survived several strong earthquakes larger than Mw>8. Besides, after the February 27th, 2010 Maule event it showed remarkable resilience due to the implementation of traditional timber retrofits inserted in the earthen walls. The use of traditional wooden devices such as bond beams, corner keys, and wooden gables, proved to be effective solutions against strong earthquakes. Therefore, this church appears as a relevant case of the use of seismic resistant constructive techniques of the17th century colonial architecture and the study of its seismic behaviour holds great interest and relevance. Aimed to assess the seismic vulnerabilityof the monument, a complete study of the church was carried out using a multi-level approach comprising historical research, in situ surveys, crack pattern analysis, physical and mechanical characterization of materials, and local and global structural analyses. In particular, the linear and incremental kinematic approaches with limit analysis have been employed with the aim of interpreting the local mechanisms activated during the 2010 Maule earthquake. In these models, the effect of friction of masonry-to-masonry and timber-to-masonry interfaces, as well as the limited tensile strength of masonry, was all considered. This study results prove the general validity in the field of timberseismic retrofitting of unreinforced adobe buildings
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    Seismic Vulnerability Assessment of Unreinforced Masonry Churches in Central Chile
    (Springer Cham, 2019) Palazzi, Nuria Chiara; Rovero, Luisa; Tonietti, Ugo; Llera Martin, Juan Carlos de la; Sandoval Mandujano, Cristián
    In the central region of Chile, the unreinforced masonry (URM) churches underwent extensive structural damage during the 2010 Maule earthquake (Mw 8.8), highlighting the importance of implementing seismic risk reduction plans. These religious buildings are characterized by profound typological and constructive peculiarities, originated by the combination of the local build culture with European architectural revivalisms(i.e., Neo-Baroque, Neo-Classic, Neo-Renaissance and Neo-Gothic)during the Spanish domination (1536–1818). The uniqueness of this heritage and the seismic risk of the Chilean territory lead to the need to define a systematic method to assess the seismic vulnerability of the Chilean URM churches. In this paper, some results of an in-depth investigation on a representative stock of churches are reported. The investigation was based on a database implementation with geometrical, constructive, and structural characteristics of 40 URM churches in the Metropolitan Region of Chile. A preliminary qualitative assessment of the seismic capacity of these churches is provided using a survey of geometric indices. Than specific damages observed after the 2010 earthquake have been related to the recurrent failure mechanisms of masonry structures, taking into account 21 local mechanisms involving the macro-elements of the churches. The average level of damage suffered by each church was calculated through the global damage index and a histogram of damage levels frequencies has been arranged. These results are preliminar suitable probabilistic tools to support seismic risk reduction plans.
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