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Item type:Publication, Development of fragility curves for confined masonry buildings in Lima, Peru(2018)This paper aims at investigating the seismic fragility of confined masonry (CM) structures in Lima, Peru, which can be used to perform earthquake scenarios at urban scale. A database describing the geometric properties (walls density, building area, height) of this type of structure was developed using data from field surveys. This information was complemented with results from experimental tests to compute a large set of capacity curves using a mechanical procedure. These models were tested against a set of ground motion records using the displacement-based earthquake loss assessment (DBELA) procedure, and the structural responses were used to derive fragility functions for four building classes. The resulting fragility curves were convoluted with seismic hazard curves to evaluate the annualized expected loss ratio and annual collapse probability. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Development of a Fragility Model for the Residential Building Stock in South America(2017)South America—in particular, the Andean countries—are exposed to high levels of seismic hazard, which, when combined with the elevated concentration of population and properties, has led to an alarming potential for human and economic losses. Although several fragility models have been developed in recent decades for South America, and occasionally used in probabilistic risk analysis, these models have been developed using distinct methodologies and assumptions, which renders any direct comparison of the results across countries questionable, and thus application at a regional level unreliable. This publication aims at obtaining a uniform fragility model for the most representative building classes in the Andean region, for large-scale risk analysis. To this end, sets of single-degree-of-freedom oscillators were created and subjected to a series of ground motion records using nonlinear time history analyses, and the resulting damage distributions were used to derive sets of fragility functions. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Displacement-Based Fragility Curves for Seismic Assessment of Adobe Buildings in Cusco, Peru(2012)The seismic vulnerability of single-story adobe dwellings located in Cusco, Peru, is studied based on a mechanics-based procedure, which considers the analysis of in-plane and out-of-plane failure mechanisms of walls. The capacity of each dwelling is expressed as a function of its displacement capacity and period of vibration and is evaluated for different limit states to damage. The seismic demand has been obtained from several displacement response spectral shapes. From the comparison of the capacity with the demand, probabilities of failure have been obtained for different PGA values. The results indicate that fragility curves in terms of PGA are strongly influenced by the response spectrum shape; however, this is not the case for the derivation of fragility curves in terms of limit state spectral displacement. Finally, fragility curves for dwellings located in Pisco, Peru, were computed and the probabilities of failure were compared with the data obtained from the 2007 Peruvian earthquake. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Structural survey and empirical seismic vulnerability assessment of dwellings in the historical centre of Cusco, Peru(Taylor and Francis Ltd., 2021-01-01)This paper deals with the seismic vulnerability assessment of dwellings in the historic centre of Cusco (Peru), one of the most important UNESCO sites in the world. This activity is framed within a cooperation agreement between the University of Chieti-Pescara (Italy), the Andina University del Cusco (Peru), the Pontifical Catholic University of Peru and the Cusco Municipality (Peru) whose main focus is the seismic risk evaluation of the whole historic centre. Following a discussion on the development of the historic centre and the main construction typologies, the paper presents the main outcomes of an extensive in-situ survey for collecting structural information on the buildings. Statistics regarding the data are given and shown in a GIS environment. The collected data are then used to implement an empirical model for the seismic vulnerability assessment of a significant part of the historic centre. The model is derived using a methodology already proposed by the authors for Italian historic centres. The original model is adapted to the peculiarities of the structural typologies found in Cusco. Finally, fragility curves are derived and used in order to assess the potential seismic vulnerability reduction achieved by applying proper retrofitting interventions at the large scale. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Seismic vulnerability evaluation of Peruvian aerial electrical substations with simulated fragility functions(International Association for Earthquake Engineering, 2021-01-01)This research uses a probabilistic methodology to evaluate the seismic vulnerability of aerial electrical substations in Perú. Peruvian electrical distribution substations are vital structures for which exists little research about their seismic vulnerability. This paper aims to be a contribution to estimate the seismic vulnerability of vital electrification lines. The proposed methodology is based on fragility functions which represent the overall structural behavior of 3D model frames for 27 aerial distribution electrical substations located in Cañete city. The Latin Hypercube technique, an enhanced Monte Carlo-base method, was used to generate fragility functions. This technique optimizes the sampling of structural parameters and provides at least 100 reliable samples for every level of seismic demand. In case of structural models, only the concrete compressive strength (f 'c), the maximum concrete strain (εcu) and the yield stress of the reinforcing steel (fy) were considered. For the concrete, mean values of 20 MPa and 0.40% were considered for compressive strength and maximum strain, respectively. For both cases, 15% coefficient of variation with a normal probability distribution function was assumed. However, for the steel, it was assumed an average value of 412 MPa, a 6.0% coefficient of variation and a lognormal probability distribution function. This is due to higher quality requirements during its fabrication. Axial force was shown to have a direct impact on curvature ductility of reinforced concrete cross sections. The seismic demand was defined by synthetic records that were compatible with the elastic Peruvian design spectrum, considering two soil types (S1 and S2) described in Peruvian seismic code. Acceleration records were scaled based on the peak ground acceleration on rigid soil (PGA) which went from 0.05g to 1.00g. A total of 2000 structural models were considered to account for both structural and seismic variability, for each soil type and aerial distribution electrical substation category. The structural models use frame elements with concentrated plastic flexure hinges. This way, the strength and stiffness degradation of the structure persists overtime. Nonlinear time-history analysis was carried out for each model subjected to a synthetic signal. This was performed with SAP 2000 program. These samples were run without user interaction through MATLAB scripts. The coupling between structural models and signals was performed with Monte Carlo simulation. On one hand, seismic vulnerability ratios for aerial electrical substations, constructed on S1 soil type, showed expected average probabilities of 99% and 88% for simple and double post substations respectively, considering a damage limit state as yielding. For the same substations, 1% and 3% ratios were computed for collapse limit state. On the other hand, considering S2 soil type, ratios showed average probabilities of 86% and 66% in yielding limit state, and 1% ratio was computed for collapse limit in both post type cases. These ratios were computed considering a seismic demand related to 10% of probability of exceedance in 50 years, which is a requirement in the Peruvian seismic code. These results show an unacceptable seismic performance for substations. They may require extensive repairing or complete post reposition. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Study of seismic vulnerability of social housing with thin RC bearing walls in the coast of Peru(International Association for Earthquake Engineering, 2021-01-01)In recent years, the Peruvian government has promoted the development of social housing projects with thin RC shear walls of limited ductility to overcome the housing deficit in popular sectors of the population. This structure system consists in 10 cm thick walls that have a single central reinforcing mesh that allows a lower cost of construction compared to traditional systems. However, there are no records of its performance to seismic events for two reasons: these new social housing began to be constructed from the year 2000 and there is a seismic silence since 1974 for the central coast of Peru. In addition, performance of this type of buildings has been studied through the fragility curve for the collapse limit state of a simplified model and the vulnerability curve based on expert opinion. The objective of the research is to contribute to improving the safety of peruvian housing through the analytical study of the seismic vulnerability of social constructions with thin RC bearing walls. The typology was first characterized by two representative models: a single-family dwelling of 2 floors and a multi-family building of 5 floors. Both typologies were represented by nonlinear models performed and calibrated with laboratory damage tests. Then, the models were evaluated to seismic demands characteristic of the central coast of South America by means of an Incremental Dynamic Analysis (IDA). Fragility structural curves were obtained for the limit state of collapse. Finally, the seismic performance of both typologies was obtained through vulnerability curves estimating the expected repair cost, based on the FEMA 58 report. The damage states associated to repair techniques costs of the walls were obtained from cyclic lateral load tests for controlled displacements carried out at the Pontifical Catholic University of Peru for SENCICO. For frequent and occasional earthquakes, imperceptible fissures due to flexion and shear predominated. For earthquakes of greater intensities structural damages is more evident. Repair techniques proposed by SENCICO are economically feasible because they represent in average 50% of the reconstruction cost for a very rare earthquake for the typology of 5 floors and 10% reconstruction cost for the 2-story typology. Next steps could be life cycle cost-benefit analysis to assess the economic losses of the typology of social housing and the elaboration of repair plans after a seismic event. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Vertical growth of masonry buildings in Peru and its role in the increase of seismic vulnerability(International Association for Earthquake Engineering, 2024-01-01)In Lima, the capital of Peru, and many cities in South America, houses tend to grow vertically. Due to financial limitations and increment of family members, houses increase a floor at different periods. As a result, their dynamic properties and performance during earthquakes change over time. Thus, it is necessary to estimate the change in the seismic vulnerability considering the height change in time. Unfortunately, today, there is no information regarding the vertical growth rate of buildings in Lima. To this aim, we have estimated the vertical growth rate of informal masonry buildings by inspecting 457 samples. The selection of the buildings was based on their availability in the Google Street View dataset, which was used to identify the number of floors in 2013. Then, the number of floors in 2023 was determined by a series of field surveys. With the number of floors at the two dates, we compute the transition matrix T. The relevance of the transition matrix lies in that it can be used to predict the number of floors in different years and assess the change in the seismic vulnerability of masonry buildings.