Departamento Académico de Ingeniería
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Item Open Access Experimental assessment of confined masonry walls retrofitted with SRG under lateral cyclic loads(2019) Yacilaa, Jhair; Salsavilcaa, Jhoselyn; Tarquea, Nicola; Camatab, GuidoAround the world, many informal masonry buildings have collapsed due to the failure of their bearing walls under lateral seismic loads. This is related to the many involved factors, such the quality of the materials, the quality of workmanship, the lack of technical intervention, and the high seismicity of the zone, among others. However, the fact is that these constructions need to be retrofitted in order to upgrade their ultimate strength and allow them to properly absorb inelastic deformations. Currently, fiber reinforced polymer (FRP) has been widely studied as a retrofitting technique. However, it has some technical and economic disadvantages that are remedied by fiber reinforced mortar (FRM). In this paper, a variant of FRM known as steel reinforced grout (SRG) is studied as a seismic retrofitting technique for cracked confined masonry walls (CMW). For this purpose, three full-scale cracked walls were repaired, retrofitted with SRG strips, and tested under in-plane cyclic loads at the Pontifical Catholic University of Peru (PUCP). The experimental results show the benefits of SRG in improving the lateral displacement ductility, energy dissipation, and stiffness degradation of CMWs.Item Open Access Multi-criteria analysis of five reinforcement options for Peruvian confined masonry walls(2019) Tarque, Nicola; Salsavilca, Jhoselyn; Yacila, Jhair; Camata, GuidoIn Peru, construction of dwellings using confined masonry walls (CM) has a high percentage of acceptance within many sectors of the population. It is estimated that only in Lima, 80% of the constructions use CM and at least 70% of these are informal constructions. This mean that they are built without proper technical advice and generally have a high seismic vulnerability. One way to reduce this vulnerability is by reinforcing the walls. However, despite the existence of some reinforcement methods in the market, not all of them can be applied massively because there are other parameters to take into account, as economical, criteria for seismic improvement, reinforcement ratio, etc. Therefore, in this paper the feasibility of using five reinforcement techniques has been studied and compared. These reinforcements are: welded mesh (WM), glass fiber reinforced polymer (GFRP), carbon fiber reinforced polymer (CFRP), steel bar wire mesh (CSM), steel reinforced grout (SRG). The Multi-Criteria Decision Making (MCDM) method can be useful to evaluate the most optimal strengthening technique for a fast, effective and massive use plan in Peru. The results of using MCDM with 10 criteria indicate that the Carbon Fiber Reinforced Polymer (CFRP) and Steel Reinforced Grout (SRG) methods are the most suitable for a massive reinforcement application in Lima.Item Open Access Development of fragility curves for confined masonry buildings in Lima, Peru(2018) Lovon, Holger; Tarque, Nicola; Silva, Vitor; Yepes-Estrada, CatalinaThis 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.Item Open Access Alternative approach for reproducing the in-plane behaviour of rubble stone walls(2017) Tarque, Nicola; Camata, Guido; Benedetti, Andrea; Spacone, EnricoStone masonry is one of the oldest construction types due to the natural and free availability of stones and the relatively easy construction. Since stone masonry is brittle, it is also very vulnerable and in the case of earthquakes damage, collapses and causalities are very likely to occur, as it has been seen during the last Italian earthquake in Amatrice in 2016. In the recent years, some researchers have performed experimental tests to improve the knowledge of the behaviour of stone masonry. Concurrently, there is the need to reproduce the seismic behaviour of these structures by numerical approaches, also in consideration of the high cost of experimental tests. In this work, an alternative simplified procedure to numerically reproduce the diagonal compression and shear compression tests on a rubble stone masonry is proposed within the finite element method. The proposed procedure represents the stone units as rigid bodies and the mortar as a plastic material with compression and tension inelastic behaviour calibrated based on parametric studies. The validation of the proposed model was verified by comparison with experimental data. The advantage of this simplified methodology is the use of a limited number of degrees of freedom which allows the reduction of the computational time, which leaves the possibility to carry out parametric studies that consider different wall configurations.Item Open Access Expected Ground Motion at the Historical Site of Poggio Picenze, Central Italy, with reference to current Italian Building Code(2013) Tarque, N.; Lai, C. G.; Bozzoni, F.; Miccadei, E.; Piacentini, T.; Camata, G.; Spacone, E.The amplification of the ground motion at the surface is greatly influenced by the geotechnical characteristics of the soil formations below the ground surface. Traditionally, analyses of the ground response are deterministic, which means no consideration of the aleatory nature of geotechnical parameters of soil layers like density, shear wave velocity, etc. A fully stochastic procedure for estimating the site amplification of ground motion allows taking into account the record-to-record variability in an input ground motion and the uncertainty in dynamic soil properties and in the definition of the soil model. In particular, their effect on response spectra at the ground surface can be evaluated. With this procedure, it is pretended to reduce the aleatory variability into the soil model. In this work, the soil profile below the San Felice Martire church, at Poggio Picenze (L’Aquila area, Abruzzo, Central Italy), has been studied basically on field geologic observations and drilling and geophysical tests retrieved from previous investigation campaigns. The dynamic soil properties were obtained by literature and by the test results. Amplification effects at the site under investigation have been estimated using fully 1D stochastic site response analyses and for the object motion 7 real records compatible to the Italian code-based spectrum referred to 475-year return period. The Italian building code defines the reference seismic action in terms of elastic acceleration response spectra derived from the results of a probabilistic seismic hazard study. The results in terms of accelerograms and acceleration response spectrum (with the associated dispersion) indicated a clear amplification of the input motion at the basement of San Felice Martire church due to the lithostratigraphic characteristics of the soil deposits at the site under investigation.Item Open Access Masonry infilled frame structures: state-of-the-art review of numerical modelling(2015) Tarque, Nicola; Candido, Leandro; Camata, Guido; Spacone, EnricoThis paper presents a state-of-the-art review of the nonlinear modelling techniques available today for describing the structural behaviour of masonry infills and their interaction with frame structures subjected to in-plane loads. Following brief overviews on the behaviour of masonry-infilled frames and on the results of salient experimental tests, three modelling approaches are discussed in more detail: the micro, the meso and the macro approaches. The first model considers each of the infilled frame elements as separate: brick units, mortar, concrete and steel reinforcement; while the second approach treats the masonry infill as a continuum. The paper focuses on the third approach, which combines frame elements for the beams and columns with one or more equivalent struts for the infill panel. Due to its relative simplicity and computational speed, the macro model technique is more widely used today, though not all proposed models capture the main effects of the frame-infill interaction.Item Open Access Nonlinear Dynamic Analysis of a Full-Scale Unreinforced Adobe Model(2014) Tarque, Nicola; Camata, Guido; Spacone, Enrico; Varum, Humberto; Blondet, MarcialThis paper describes the results of a numerical study of a full-scale adobe building model tested on a shaking table. Material properties of adobe masonry were calibrated to represent the wall in-plane seismic behavior, based on a prior numerical analysis of an adobe wall carried out by the authors. The inelastic part of the constitutive model was represented by a softening curve in tension and by a hardening/softening behavior in compression; thus, the fracture energy is a key issue in the modeling process. A finite element model that relies on a homogenous continuum approach was developed in Abaqus/Explicit software. The damage evolution in the numerical simulation represented fairly well the experimental crack pattern, for in-plane and out-of-plane seismic effects. Overall, the calibrated material properties and the explicit solution scheme proved to be appropriate for simulating the seismic behavior and predicting capacity of unreinforced adobe structures subjected to seismic loading.Item Open Access Displacement-Based Fragility Curves for Seismic Assessment of Adobe Buildings in Cusco, Peru(2012) Tarque, Nicola; Crowley, Helen; Pinho, Rui; Varumd, HumbertoThe 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.Item Open Access Numerical simulation of an adobe wall under in-plane loading(2014) Tarque, Nicola; Camata, Guido; Varum, Humberto; Spacone, Enrico; Blondet, MarcialAdobe is one of the oldest construction materials that is still used in many seismic countries, and different construction techniques are found around the world. The adobe material is characterized as a brittle material; it has acceptable compression strength but it has poor performance under tensile and shear loading conditions. Numerical modelling is an alternative approach for studying the nonlinear behaviour of masonry structures such as adobe. The lack of a comprehensive experimental database on the adobe material properties motivated the study developed here. A set of a reference material parameters for the adobe were obtained from a calibration of numerical models based on a quasi-static cyclic in-plane test on full-scale adobe wall representative of the typical Peruvian adobe constructions. The numerical modelling, within the micro and macro modelling approach, lead to a good prediction of the in-plane seismic capacity and of the damage evolution in the adobe wall considered.Item Open Access Development of a Fragility Model for the Residential Building Stock in South America(2017) Villar-Vega, Mabé; Silva, Vitor; Crowley, Helen; Yepes, Catalina; Tarque, Nicola; Acevedo, Ana Beatriz; Hube, Matías A. A.; Gustavo, Coronel D.; Santa María, HernánSouth 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.