Numerical modelling of in-plane behaviour of adobe walls

Some tests for material characterization of adobe blocks and adobe masonry have been carried out in universities and laboratories around the world. However, the number of tests is quite limited in comparison with those carried out with other structural materials, such as masonry or reinforced concrete, and even those tests just refers to elastic properties. The results of adobe tests (i.e. compression strength, elasticity modulus, shear strength, etc.), as well as the results of cyclic and dynamic tests on adobe masonry components and small buildings show that the mechanical properties of adobe masonry and the seismic performance of adobe constructions highly depend on the type of soil used for the production of units and mortar. Basic properties, such as elasticity modulus, can have significant variation from one soil type to another. The state-of-the-art for the numerical modelling of unreinforced masonry point to three main approaches: macro-modelling, simplified micro-modelling and detailed micro-modelling. In all three approaches, the use of elastic and inelastic parameters is required. For adobe masonry, the lack of knowledge concerning some of the material properties makes numerical modelling more difficult. In the proposed work, the mechanical properties of the typical adobe masonry in Peru have been calibrated based on a cyclic in-plane test carried out on an adobe wall at the Catholic University of Peru (PUCP). The mechanical parameters calibration and the modelling results of the in-plane behaviour of the adobe wall are presented. Macro-modelling and simplified micro-modelling strategies are used in finite element software with an implicit solution strategy. The results of this work represent the first step for the numerical modelling of the seismic behaviour of adobe constructions

The use of continuum models for analyzing adobe structures

As it is known, the adobe structures have a high seismic vulnerability principally due to the low material strength and sometimes due to the inadequate structural configuration. One way for understanding the seismic behaviour of these structures is by experimental tests. However, those are costly and sometimes not easy to make. An alternative for this is the analysis of adobe structures by numerical tools with the possibility to make parametric studies for understanding the behaviour of different geometrical configurations. In a previous work, some adobe material parameters have been calibrated based on a cyclic in-plane test. In this paper, that work was extended to a numerical modelling of the non-linear dynamic behaviour of an adobe module experimentally tested at the Pontificia Universidad Católica del Perú. For this, a continuum model in the finite element program Abaqus/Explicit, was used to represent the adobe masonry as a homogeneous and isotropic material

Análise das raízes complexas de uma equação quadrática e estudo de números complexos no ensino médio

Neste trabalho, propomos uma atividade de investigação sobre o lugar geométric

Evaluation of the additional shear demand due to frame-infill interaction: a new capacity model

During earthquakes, masonry infills exert a significant stiffening and strengthening action which can be favourable or adverse to face the earthquake-induced demand. Infills transfer the force increment to the RC frame members as an additional shear force. Because of this, local shear failures at the end of the columns, or at the end of the beam-column joints can occur. This is particularly true in the case of non-seismically conforming frame structures, as also shown by post-earthquake damage revealed by recent and past earthquakes. Assessment of this additional shear demand is not possible using the common equivalent strut model for the infills. On the other hand, 2D inelastic models are not computationally effective to be used for seismic analysis of large and complex buildings. Because of this, the actual shear demand on columns is underestimated in most cases. In order to maintain the simplicity of the equivalent strut approach without losing the information about the actual shear force on the columns, the current paper provides a detailed study about the infill-frame shear transfer mechanism. Refined 2D inelastic models of real experimental tests on infilled frames have been realized in OpenSees with the aid of the STKO pre and post processor platform. Shear demand on the columns is extracted as on output of the simulations and compared to the axial force resulting from the same simulations made with the equivalent strut models. An analytical relationship allowing estimate the additional shear demand as a function of the current axial force on the equivalent struts and the geometrical and mechanical properties of the infilled frames is finally proposed. The formula can be easily used to perform shear safety checks of columns adjacent to the infills in seismic analyses

Multiscale computational first order homogenization of thick shells for the analysis of out-of-plane loaded masonry walls

This work presents a multiscale method based on computational homogenization for the analysis of general heterogeneous thick shell structures, with special focus on periodic brick-masonry walls. The proposed method is designed for the analysis of shells whose micro-structure is heterogeneous in the in-plane directions, but initially homogeneous in the shell-thickness direction, a structural topology that can be found in single-leaf brick masonry walls. Under this assumption, this work proposes an efficient homogenization scheme where both the macro-scale and the micro-scale are described by the same shell theory. The proposed method is then applied to the analysis of out-of-plane loaded brick-masonry walls, and compared to experimental and micro-modeling results

Regularization of first order computational homogenization for multiscale analysis of masonry structures

The final publication is available at Springer via http://dx.doi.org/10.1007/s00466-015-1230-6 This paper investigates the possibility of using classical first order computational homogenization together with a simple regularization procedure based on the fracture energy of the micro-scale-constituents. A generalized geometrical characteristic length takes into account the size of the macro-scale element as well as the size of the RVE (and its constituents). The proposed regularization ensures objectivity of the dissipated energy at the macro-scale, with respect to the size of the FE in both scales and with respect to the size of the RVE. The proposed method is first validated against benchmark examples, and finally applied to the numerical simulation of experimental tests on in-plane loaded shear walls made of periodic masonry

FRCM retrofitting techniques for masonry walls: a literature review and some laboratory tests

The experimental characterisation of externally bonded composite materials as strengthening solutions for masonry structures, such as basalt textile reinforced mortar (BTRM) or fiber reinforced concrete (FRC), has been receiving increasing attention due to their outstanding mechanical performance. Several studies have been demonstrated the efficiency of this retrofitting solution for increasing the mechanical strength and the displacement capacity of masonry material. In this paper the state-of-art of the most relevant achievements in the experimental investigations and numerical analysis of retrofitted masonry wall have been critically reviewed. Firstly, a detailed collection of several experimental tests using different textile reinforced mortar and/or fiber reinforced mortar has been conducted. Special focus has been given to the test set-up and load configuration type adopted for experiments. Subsequently, several modelling techniques have been treated in order to detect the best approach simulating the interaction between reinforcement system and masonry ranging from macro and micro modelling, concentrated and diffused plasticity model and diverse constitutive laws. Finally, an overview of some original experimental outcomes from laboratory tests is presented. This results will play a major role in for the validation of the numerical models for the prediction of the shear strength and the ductile behavior of reinforced masonry that will be developed in a further step of this research

Equivalent Frame Method Combining Flexural and Shear Responses of Masonry Buildings

This work presents the results of quasi-static non-linear analyses of two masonry buildings using, for the discretization of walls, a macro-element that combines the bending and the in-plane shear responses. The macro-element uses the force-based beam- column element equipped with cross sections discretized in fibers, where the behavior of each fiber is described by uniaxial constitutive models. To describe the shear response of the structural element, the macro-element embeds a shear hinge at mid-span, with a phenomenological non-linear constitutive model calibrated on experimental data. The analyzed buildings are two tangibles examples of un-reinforced and reinforced masonry of the Italian Heritage. The un-reinforced masonry building is a strategic building monitored by the O.S.S., partially damaged by the seismic events in Center Italy in 2016. The reinforced masonry building, a three-storey residential structure, is subject of evaluations carried out in the ReLuis RINTC project, designed as per D.M. 2018

Culture, education and water resources management: a literature review highlighting new research opportunities

Given that water is a conditioning and irreplaceable element to the existence of life on Earth, equally present and future populations also depend on water to ensure their continuity and economic activities, biological and sociocultural factors that develop. Based on a review of the scientific literature available in EBSCO and Web of Science databases, this study aimed to investigate and discuss the existing relationships between culture and education in the context of water resources management. We conducted a systematic literature review technique in conjunction with a bibliometric analysis with the support of Rayyan, Microsoft Excel, and VOSviewer software. For the data collection, we evaluated the sample regarding the number of annual publications, the mapping of publications, and the relations network between the keywords created to identify new trends and a research agenda. The results highlighted the complexity of the relationship between culture, education, and water resources, revealing the need to deepen and advance research on the subject. In the analysis, we identified the need to consider man as the leading actor in a new structure in which education will be the leading mobilizer for constructing a new cultural perspective on water resource management

RINTC-E: Towards seismic risk assessment of existing residential reinforced concrete buildings in Italy

The RINTC research project (RINTC Workgroup, 2018), financed by the Italian Department of Civil Protection, is aimed at evaluating the seismic risk of buildings conforming to the Italian building code. Within the framework of this project, the attention has been recently focused on existing buildings, too. In this study, case-study structures, representative of the existing residential reinforced concrete (RC) building stock in Italy, are analyzed. These structures are three-storey buildings with compact rectangular plan, and they have been defined through a simulated design process, in order to represent two types of buildings, namely designed for gravity loads only during 1970s (gravity load designed, GLD) or for moderate seismic loads during 1990s (seismic load designed, SLD). GLD buildings are assumed to be located in three different sites, namely Milan, Naples and Catania, in increasing order of seismic hazard. SLD buildings are assumed to be located in L'Aquila. The assumed design typologies are consistent with the seismic classification of the sites at the assumed ages of construction. The presence of typical nonstructural masonry infill walls (uniformly distributed in plan as external enclosure walls) is taken into account, assuming three configurations along height, namely “bare” (without infills), uniformly infilled and “pilotis” (without infills at the bottom storey) buildings. Two (not code-based) Limit States are investigated, namely Usability-Preventing Damage, corresponding to an interruption of the building use, and Collapse. RC elements are modelled with a lumped plasticity approach, through an empirical-based macromodel. The possible occurrence of shear failures in columns is taken into account through a preliminary classification of the expected failure mode (flexure- or shear-controlled, in the latter case prior to or following flexural yielding) and, if needed, a modification of the backbone of the nonlinear moment-chord rotation response, through empirical models providing the expected deformation capacity at shear and axial failure, the latter meant as the (initiation of) loss of axial-load-carrying-capacity. The nonlinear response of beam-column joints is modelled, too, with a “scissors model” based on concentrated springs representing the nonlinear response of the joint panel, at the intersection of beams' and columns' centerlines, through a preliminary evaluation of the expected failure mode (i.e. prior to or following yielding of adjacent beam/column elements). Materials properties are provided by literature studies, consistent with the age of construction of the buildings. The in-plane response of infills is modelled, taking into account the presence of openings, too. Modeling should be considered as simplified and, from some points of view, still preliminary, since advances are foreseen within the project in order to capture further failure modes that can occur in structural and nonstructural elements of older, nonductile RC buildings. Nonlinear static analyses, allowing to identify the (top) displacement capacity at the investigated Limit States, are carried out. Multiple stripe nonlinear time history bi-directional analyses of the three-dimensional structural models are carried out in order to evaluate the demand, for ten stripes - each corresponding to a return period ranging from 10 to 105 years - and for twenty couples of records for each stripe. Records were selected, within the activities of the research project, based on a Probabilistic Seismic Hazard Analysis at the sites of interest for the selected return periods. Results are illustrated, highlighting the role of a - although obsolete - seismic design in the response of the buildings and in their capacity, more specifically in terms of displacement capacity at Collapse, but also in terms of demand estimated from multiple stripe analyses. Finally, demand-to-capacity ratios at the investigated Limit States are analyzed, which allow, within the scope of the project, the assessment of the seismic risk of the case study structures