Simulation of Shake Table Tests on Out-of-Plane Masonry Buildings. Part (VI): Discrete Element Approach

ABSTRACT

Although many experimental tests and numerical models are available in the literature, the numerical simulation of the seismic response of existing masonry buildings is still a challenging problem. While the nonlinear behavior of masonry structures is reasonably predictable when the out-of-plane behavior can be considered inhibited, when the in-plane and out-of-plane responses coexist and interact, simplified models seem unable to provide reliable numerical predictions. In this article, taking advantage of the experimental tests carried out in a shaking table on two masonry prototypes at LNEC, a macro-element approach is applied for the numerical simulations of their nonlinear response. The adopted approach allows simulating the nonlinear behavior of masonry structures considering the in-plane and out-of-plane responses. Since it is based on a simple mechanical scheme, explicitly oriented to representing the main failure mechanisms of masonry, its computational cost is greatly reduced with respect to rigorous solutions, namely nonlinear FEM approaches. Two modeling strategies are adopted, namely a regular mesh independent from the real texture of the prototypes and a detailed one coherent with the units disposal. The numerical results are discussed and the correlation between the nonlinear static analyses and the dynamic response is provided.     

Methods and Approaches for Blind Test Predictions of Out-of-Plane Behavior of Masonry Walls: A Numerical Comparative Study

ABSTRACT

Earthquakes cause severe damage to masonry structures due to inertial forces acting in the normal direction to the plane of the walls. The out-of-plane behavior of masonry walls is complex and depends on several parameters, such as material and geometric properties of walls, connections between structural elements, the characteristics of the input motions, among others. Different analytical methods and advanced numerical modeling are usually used for evaluating the out-of-plane behavior of masonry structures. Furthermore, different types of structural analysis can be adopted for this complex behavior, such as limit analysis, pushover, or nonlinear dynamic analysis.

Aiming to evaluate the capabilities of different approaches to similar problems, blind predictions were made using different approaches. For this purpose, two idealized structures were tested on a shaking table and several experts on masonry structures were invited to present blind predictions on the response of the structures, aiming at evaluating the available tools for the out-of-plane assessment of masonry structures. This article presents the results of the blind test predictions and the comparison with the experimental results, namely in terms of formed collapsed mechanisms and control outputs (PGA or maximum displacements), taking into account the selected tools to perform the analysis.     

A Crisis of Opportunity: Market-Making,Big Data,and the Consolidation of Migration as Risk

Crisis narratives surrounding Europe’s 2015 migration influx fuelled demands for new ways of tracking, mapping and predicting human mobility. We explore how market opportunities for technology firms and data analytics start-ups created by the EU’s Global Approach to Migration led to solutionistic approaches to compiling and analysing migration statistics. We show that initiatives such as the rebranding of existing platforms and services as migration prediction systems are consolidating policy conceptualisations of migration as risk. Despite the promise of greater granularity, this “big data approach” cannot offer greater certainty about who is on the move and why. Instead such approaches are ill-suited to understanding the complex dynamics of migration and to offering protection to vulnerable people. The marketisation of migration statistics through big data offers a key case for advancing progressive approaches to both migration statistics and global data justice.     

Kaparlgoo Blue: On the Adoption of Laundry Blue Pigment into the Visual Culture of Western Arnhem Land,Australia

International Journal of Historical Archaeology - It has been argued that laundry blue (whitener) was introduced into western Arnhem Land in the second half of the 1920s by missionaries, where it...     

Assessment of the Permeability of Historical Defensive Systems: the Case of the Lines of Torres Vedras

As the largest part of military usage of the territory depends on a thorough analysis of its morphology, spatial analysis with Geographic Information Systems (GIS) software reveals a great potential as a way for studying battlefields and/or other military buildings and scenarios from the past, while supporting interpretations of territorial occupation and related organization of military forces through event simulation. This paper presents a GIS-based method to model and assess the permeability of historical defensive systems from the period that preceded the mechanization of warfare of the late nineteenth century, i.e., based on artillery installed in fortifications. The method was applied to analyze the permeability of the Lines of Torres Vedras (LTV) defensive system, a multi-line fortification complex which was operational during the Peninsular War in the beginning of the nineteenth century and located north of Lisbon, Portugal. The structures of the LTV and local terrain were modelled in GIS using a set of proposed parameters that support territorial analysis, combined with the capability of contemporary weaponry. A methodical quantification and combination of these parameters enabled a better understanding of the systemic design of the defensive lines in terms of its permeability, contributing to a discussion of the LTV particular military setting based on the interpretation of these indicators. Global and sectorial analyses of the permeability of the LTV defensive system were conducted.     

Mapping the Stone Age of Mozambique

Under the auspices of the Portuguese colonial government, Lereno Barradas and Santos Júnior (coordinator of the Anthropological Mission of Mozambique) carried out several archaeological field surveys from 1936 to 1956 that resulted in a data set that includes a total of close to 90 sites, mostly attributed to the Stone Age. This early research added to the previous work of Van Riet Lowe in the Limpopo Valley of southern Mozambique. With the new millennium, Mozambique has emerged as a crucial geographic area in which to understand the various hypotheses about recent human evolution. Specifically, its coastal location between southern and eastern Africa is ideal for testing ideas about the link between early coastal adaptations and the appearance of anatomically modern humans (AMH). Except for the recent work by Mercader’s team in northern Mozambique, the number of researchers and projects on this topic in Mozambique is still limited because of the general predominance of interest in later periods among archaeologists working in the country, mainly due to their focus on issues related to precolonial heritage and national identity. Based on the early maps from Santos Júnior and more recent data acquired through various projects, we present a series of maps for the Stone Age prehistory of Mozambique. The maps are also based on a critical evaluation of the sites and a review of some of the materials that are presently curated at the Instituto de Investigação Científica e Tropical (IICT) in Lisbon, Portugal, as well as the materials stored at the Department of Archaeology of Universidade Eduardo Mondlane, Maputo. The sites are also presented in an online database with the information on all sites used in this study. This database is open to all and will be updated continuously. A preliminary interpretation of the regional distribution of the sites is also attempted, linking aspects that include region, topography and altitude, geomorphology, and cultural phase. These results will be the first step for research and knowledge in Mozambique on Stone Age prehistory and the emergence and settlement pattern of AMH.     

The Hidden Consequences of Credit: An Illustration from Rural Indonesia

Interest in rural financial development has been booming, but often with a blind eye to the broader consequences. Very few studies have tackled the unintended economic, social and ecological outcomes of ordinary indebtedness, the inevitable other side of credit. This article explores some of the main ‘hidden’ side‐effects of credit/debt relations, with special reference to the Indonesian plantation sector. I argue that widespread credit/debt relations are not only an important factor behind capital, land and labour control; they also generate constraints that foster market discipline and contribute to undermine traditional community bonds as well as environmental conditions. More generally, credit/debt relations represent a powerful mechanism of social selection that has, in the long run, crucially shaped the trajectory of capitalism at the household, firm and government levels.