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.     

Pottery Production in the Buddhist Communities in Central Asia: The Kushan‐Sassanian Pottery Workshop of Kara Tepe (Termez,Uzbekistan)

We present the first full archaeometrical study of Kushan‐Sassanian pottery from the Buddhist monastic complexes at Kara Tepe (Termez, Uzbekistan), recovered both in the pottery workshop and in the monastery, using a combination of analytical methods (XRF, XRD, SEM–EDS and OM). The study allowed the identification of the reference group, the correspondent fabric, the raw materials used for its productions, some of the technological processes involved in manufacture and several weathering processes. All the results confirm that the kiln was supplying the religious community of the monastery with pottery, made using local raw materials, and highlight the possibility that the kiln could have supplied the nearby monastic complexes, where no kilns have been found. Further archaeological evidence indicates the existence of specialized potters working itinerantly at the broader Bactrian area.     

Sherds on the Edge: Characterization of 16th Century Colonial Spanish Pottery Recovered from the Solomon Islands

We present the results of instrumental neutron activation analysis of ceramics recovered from the Solomon Islands, associated with Alvaro de Mendaña y Neira's 16th century colonizing expedition to the region (c.1595–6). Based on the chemical and typological data and previously published petrological and geochronological research, this study assigns the provenance of the ceramics variously to Peru, Panama, Spain, China and Thailand. A comparison of the provenance results with historical records related to Mendaña's voyage also shows the value of the archaeological assemblage in providing a detailed picture of provisioned ceramic types and their provenance.     

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 role of shellfish in hunter–gatherer societies during the Early Upper Palaeolithic: A view from El Cuco rockshelter,northern Spain

The role of coastal resources in the subsistence strategies of Palaeolithic human populations has only recently become an important topic in Old World archaeology. Information on the exploitation of these resources, both as foodstuffs and symbolic elements, can be used to infer the emergence of modern human behaviour as well as to track the diversification and intensification of human diet over time. The excavations carried out at El Cuco rockshelter, located in northern Spain have provided evidence for the exploitation of marine resources during the Early Upper Palaeolithic. The accumulation of Patella shells at El Cuco provides the largest accumulation and the first clear evidence of collection and consumption of molluscs during the Aurignacian on the Atlantic Façade of Europe. A deposit of ornamental shells appeared in a very homogeneous context dated to the Gravettian, suggesting that the shells belonged to the same item. The analysis of this evidence has allowed us to conclude that marine resources were systematically used at least from the beginning of the Upper Palaeolithic in the region. However, a comparison with the Mesolithic shows that intensive shellfish gathering did not occur until the end of the Upper Palaeolithic. Regarding the ornaments, it is interpreted that the identified shell beads were used as social or personal status markers.     

Lagos leprosarium (Portugal): evidences of disease

In 2009, an archaeological intervention in the Valle da Gafaria (Lagos, Portugal) allowed the excavation of part of a leprosarium and an associated necropolis (15th–17th centuries). The individuals recovered were buried directly in the soil, in positions and orientations discordant to the prevailing Christian rules. The sample is made up of eleven adult individuals of both sexes.