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

ABSTRACT

The analysis of the shaking table test of a 3-wall stone masonry structure performed with a discrete element model is presented. The numerical model, created with the code 3DEC, employed a rigid block representation and a Mohr-Coulomb joint model. Joint stiffness calibration to match the experimental natural frequencies is discussed, as well as the boundary conditions to simulate the shake table. Comparisons are made with the measured displacements at key locations, and the modes of deformation and fracture of the walls. The DEM model was able to reproduce important features of the shaking table tests. The experimental deformation and near collapse patterns were clearly identifiable in the numerical simulations, which produced displacements within the observed orders of magnitude, for the various levels of excitation.     

Forensic Ar/Ar dating: a provenance study of Middle Stone Age obsidian artifacts from Ethiopia

Obsidian sourcing based on geochemistry is widely applied to reconstruct commerce patterns and dissemination of early hominid groups. Due to problems concerning potential intra-source variability or homogeneity of a geological source over large areas, parameters additional to this classical approach are desirable. Here we present the first ⁴⁰Ar/³⁹Ar investigation of Middle Stone Age (MSA) obsidian artifacts (i.e. debitage pieces) for this purpose, as well as of potential geological obsidian sources from Ethiopia. With the present pilot study we demonstrate that ⁴⁰Ar/³⁹Ar geochronology represents a reliable and powerful tool for archaeological provenance studies complementary to the geochemical approach and more recently applied techniques like fission track counting or Mössbauer spectroscopy. Two independent sets of debitage and potential source rock samples were dated by the ⁴⁰Ar/³⁹Ar method. Debitage pieces from the Kulkuletti excavation site and obsidian samples from the nearby obsidian outcrop Worja (central Ethiopia) exhibit basically identical age ranges as well as similar Ca/K and Cl/K ratios, supporting the debitage/source rock relationship previously inferred on geochemical grounds. A second small set of geochemically characterized debitage samples from the Porc Epic cave and potential source rocks from an obsidian outcrop at Kone (Eastern Ethiopia) however have different ⁴⁰Ar/³⁹Ar ages and Ca/K and Cl/K ratios. These results contradict the previous conclusion about a debitage/source rock relationship of the Porc Epic and Kone samples made on the basis of geochemistry [A. Negash, M.S. Shackley, Archaeometry 48 (2006) 1]. Additional sampling at the Kone outcrop as well as of other obsidian occurrences in the greater area is needed to unambiguously pinpoint the origin of these obsidian tools.     

梁“中大通二年”纪年摩崖的发现——栖霞寺千佛岩61号佛龛南梁纪年题名石刻

2000年在栖霞寺千佛岩窟区61号佛龛门楣上寻访到纪年题名石刻,此次发现提供了开凿于齐梁间的千佛岩石窟的准确竣工年代,纠正了过去石窟竣工于梁天监十年的说法,并为鉴定同类时代的佛龛提供了重要依据。     

石鼓制作年代综考

本文在石鼓文“秦文公年代说”的基础上,从石鼓颂诗产生的历史时期、对秦人“若石——神(鬼)”崇拜及文公时社会氛圈和习俗的分析、石鼓最初所在地与文公作“陈宝祠”地址的一致性、文字形体及其书写风格的考察四个方面,对石鼓制作年代作进一步考证,认为：石鼓是秦文公十九年(或略晚些时侯)秦人崇拜“若石”(即陨石)、祭奠先祖而作并刻诗。石鼓文属春秋早期秦文字。     

Stone circles and the structure of Bronze Age society

Analyses of modern human societies have consistently demonstrated the presence of recurrent grouping levels forming a nested, hierarchical structure. That this structure exists in both hunter-gatherer and western industrialized societies suggests that it may be a fundamental organizing principle of considerable antiquity. Stone circles are perceived as being foci of aggregation for prehistoric groups and thus provide a proxy for the sizes of those aggregations. Combining an empirical analysis of a sample of 140 stone circles with a Monte Carlo simulation model that derives expectations for a continuous size distribution based on the nested hierarchy concept, the current paper suggests that similar organizing principles were already in place during the Bronze Age. Furthermore, it is suggested that findings traditionally attributed to the operation of the ‘rank-size rule’ may in fact reflect the basic underlying structure of human society.     

Prepared core reduction at the site of Kudu Koppie in northern South Africa: temporal patterns across the Earlier and Middle Stone Age boundary

Kudu Koppie is a stratified late Earlier Stone Age and Middle Stone Age archaeological site located in the northern Limpopo Province of South Africa. The prepared core reduction strategies are described and temporal trends across the ESA–MSA boundary are presented. The prepared cores and endproducts of Kudu Koppie suggest that both the late ESA and MSA toolmakers employed the Levallois Volumetric Concept, but they often exploited a nodule's natural convexities and form. The MSA toolmakers used a greater variety of prepared core methods and more intensively exploited cryptocrystalline and microcrystalline nodules, the scarcity of which may have resulted in a more “formalized” application of the Levallois Volumetric Concept. These observations are considered within the context of human behavioural evolution.     

Thermoluminescence dating of a Stillbay–Howiesons Poort sequence at Diepkloof Rock Shelter (Western Cape,South Africa)

New excavations have been undertaken at Diepkloof Rock Shelter (DRS; South Africa) since 1999. It is one of the very few sites where Howiesons Poort and Stillbay assemblages can be collected from the same archaeological sequence. These Middle Stone Age techno-complexes are particularly interesting for their affinities with the much younger Later Stone Age facies, and their association with evidence for symbolic behaviour. Establishing their chronology is therefore particularly important for the understanding of the apparition and the evolution of the so-called “modern” behaviours. Data already available suggest ages ranging from 55 to 80 ka for the Howiesons Poort and from 70 to 80 ka for the Stillbay techno-complexes in several South African sites. The thermoluminescence dating undertaken at DRS on 22 stone samples originating from the entire stratigraphic record indicates intervals starting 10–50 ka earlier for these techno-complexes in this site. Possible caveats in the dating process are examined but to the best of our current knowledge must be rejected.     

一件海外回流石棺床之我见

2004年,中国文物信息咨询中心征集到一件流失海外多年的石棺床,随后入藏首都博物馆。本文首次对这件石棺床进行了详细的介绍,并与同类石棺床的结构、画像风格、年代进行了比较研究,同时还对带有屏风、双阙结构石棺床的定名和使用功能进行了探讨。     

Settlement history in the eastern Rub al-Khali: Preliminary Report of the Dubai Desert Survey (2006–2007)

Regional archaeological survey in desert areas of Dubai, U.A.E., has identified numerous archaeological sites in this rapidly changing landscape. Subsurface geophysical surveys have been undertaken in concert with surface collection and test excavation to document the extent and chronology of each site. Contrary to expectations that deserts were permanently abandoned following the end of the mid-Holocene pluvial phase around 4000 BC, two sites, Al-Ashoosh and Saruq al-Hadid, show evidence of substantial occupation during the late third and early first millennia respectively. These findings suggest that the Rub al-Khali supported human settlement much later than is generally thought, challenging traditional understandings of the region's cultural and environmental histories.