Effects of Geometrical Features on the Seismic Response of Historical Masonry Towers

ABSTRACT

Historical masonry structures are often located in earthquake-prone regions and the majority of them are considered to be seismically vulnerable and unsafe. Historical masonry towers are slender structures that exhibit unique architectural features and may present many inadequacies in terms of seismic performance. The seismic protection of such typologies of structures and the design of effective retrofitting interventions require a deep understanding of their behavior under horizontal loads. This paper presents the results of the seismic performance evaluation of historical masonry towers located in Northern Italy. A large set of case studies is considered, comprising a significant number of towers with high slenderness and marked inclination. First, a preliminary assessment of the dynamic behavior of the different towers is carried out through eigenfrequency analyses. Then, non-linear dynamic simulations are performed using a real accelerogram with different peak ground accelerations. A damage plasticity material model, exhibiting softening in both tension and compression, is adopted for masonry. The huge amount of results obtained from the non-linear dynamic simulations allows a comparative analysis of the towers to be performed in order to assess their seismic vulnerability and to show the dependence of their structural behavior on some geometrical characteristics, such as slenderness, inclination, and presence of openings and belfry. The evaluation of different response parameters and the examination of tensile damage distributions show the high vulnerability of historical masonry towers under horizontal loads, mainly in the presence of marked inclination and high slenderness. Some general trends of the seismic behavior of the towers are deduced as a function of the main typological features.     

Scalar Structure-Specific Ground Motion Intensity Measures for Assessing the Seismic Performance of Structures: A Review

The assessment of the seismic performance depends on the choice of the earthquake Intensity Measure (IM). During the past years many IMs, which take into account not only earthquake characteristics but also structural information, have been proposed. However, no consensus on which IM is the best predictor of the seismic response exists. Along these lines, the objective of this paper is to present the various developed scalar structure-specific seismic IMs and the problems associated with their use in practice, so that the engineer may become familiar with them and their implications in the context of Performance-Based Earthquake Engineering.     

PROVENANCING AND ARCHAEOLOGY OF ROMAN MILLSTONES FROM SARDINIA (ITALY)

Summary. Sardinia was an important Roman settlement and trade centre between 238 BC–500 AD and is an ideal site for study of Roman trade. Study of Roman millstones in Sardinia shows that the commonest type is the Pompeian (hour-glass) mill (forty-eight stones studied), with smaller numbers of cylindrical hand querns (sixteen stones studied). Most of these millstones are composed of igneous rocks which include grey vesicular lavas of basic/intermediate composition and a distinctive reddish rhyolitic ignimbrite. There is historical and archaeological evidence for millstone manufacture at six localities in Sardinia. Visual and petrographic study and X-ray fluorescence analysis for major and trace elements of seventeen millstone samples, and fifty rock samples from potential source areas have been used to provenance the igneous rock millstones. The grey vesicular lava millstones have varied sources within the Tertiary-Recent volcanic rocks of Sardinia, while the millstones composed of rhyolitic ignimbrite are from a single source of Tertiary ignimbrite at Mulargia (central west Sardinia). A single hand mill from the north of Sardinia was imported probably from Agde in southern France, and is the only sample composed of non-local rock. Mulargia millstones were widely traded within the western Mediterranean and show a rapid decrease in frequency of occurrence with increasing distance from the source. Sardinia was therefore an important centre of Roman millstone production and a source of millstone trade during the period of Roman settlement.     

Poaceae phytoliths from the Niassa Rift,Mozambique

The most common grass phytoliths from “Zambezian” miombos are described here for the first time. Their potential for long term preservation in sediments makes them a useful tool in the reconstruction of ancient plant communities and plant/human interactions. We processed 60 plant samples (26 identified genera and species), with an average of 300 phytoliths counted per sample to a total of 18,586. Forty-seven morphotypes were described as per the International Code for Phytolith Nomenclature, with exceptions, including forty-five discreet shapes and two articulated forms, which can be used as comparative reference materials. We conducted three forms of statistical analyses: Discriminant Analysis, Cluster Analysis, and Principal Component Analysis. The highest biomineral content was recorded among the Bambuseae and Paniceae, while the lowest silica production is detected in the Cynodonteae tribe. Typologically, the subfamily Panicoideae yielded 50% of the types reported here, 32% are from the Chloridoideae, 12% from the Bambusoideae, and 8% from the Arundinoideae sensu lato. Overall, the idealized Zambezian Poaceae phytolith spectrum is dominated by a small subset of Poaceae short cells, which include five morphotypes conventionally associated with Panicoid grasses (Bilobate concave outer margin long shaft, Bilobate concave outer margin short shaft, Bilobate convex outer margin long shaft, Bilobate convex outer margin short shaft, Cross), one morphotype commonly seen in Chloridoid taxa (saddle), and two types that appear across subfamily boundaries (tower, tower horned). The next logical step to take in regional phytolith research is the account of phytoliths deposited in soils underneath living plants, for they represent the interface between existing vegetation communities and the inevitably distorted fossil assemblages that the paleobotanist uses for environmental reconstruction.     

Production centers of cooking pots in Iron Age Judah

This paper will present and discuss a multifaceted research project dealing with the production of cooking pots during the Iron Age II (ca. 1,000–586 BCE) Judah (modern Israel). In particular the new compositional analysis of 541 cooking vessels from 11 sites in Iron Age Judah will be presented. The study employs petrographic and chemical (NAA) analysis. The results of this ongoing research have already produced interesting information about production centers and movements of cooking pots in Iron Age II Judah. Apparently, the vast majority of the cooking pots sampled were made of a similar type of clay, related to terra rossa soil. This is true also for sites in the northern Negev and Judean Desert, where the type of soil was not available in the region of the sites. Furthermore, many of the cooking pots distributed around Judah were made in Jerusalem according to a well-located chemical profile (JleB). Other groups may represent Judean Shephelah production centers as the Lachish area as well as production centers in southern Israel or ancient Edom. The implications of the importation patterns of cooking pots by peripheral Judean sites will be discussed.     

故宫太和殿动力特性与常遇地震响应

为更好地保护故宫太和殿,采用有限元分析方法,研究了太和殿的动力特性及常遇地震作用下的响应。采用弹簧单元模拟榫卯节点及斗拱构造,并考虑柱础为铰接,建立了太和殿有限元模型。通过模态分析,获得了太和殿基频及主振型;通过对模型进行时程分析,获得了典型节点的位移、加速度响应曲线,以及典型单元的内力响应曲线,评价了太和殿的抗震性能。结果表明:太和殿基频为0.9Hz,主振型以平动为主;常遇地震作用下,太和殿能保持稳定振动状态,结构的内力和变形均在容许范围内,且斗拱及榫卯节点均能发挥一定的减震作用。     

Daily growth increments on fish otoliths as seasonality indicators on archaeological sites: The Tilapia from late palaeolithic Makhadma in Egypt

Daily growth increments in fish otoliths have been demonstrated for the first time on Quaternary sagittae from a late palaeolithic site in Egypt and they have allowed us to establish the season of fishing. Transverse sections of tilapia sagittae studied under light-microscope demonstrate that recrystallization during diagenesis renders the majority of the margins unreadable. The well-preserved otoliths, however, all have widely spaced outer growth lines, indicating that the fish died during a period of fast growth which coincides with the flood season. Moreover, counting the daily increments showed that late palaeolithic man captured the animals on the floodplain of the Nile after the maximum of the flood, when residual pools were present.     

我国图们江地区开发的动态趋向及其图形演示

文章以图文结合的方式演示了我国图们江地区开发的动态趋向,揭示了该地区在未来开发过程中作为国际物流中心及交通枢纽的作用,以及地区产业开发的空间过程,进而提出了未来地区人口分布与城镇体系建设的初步设想。     

左江流域种植业区划

左江流域六县(市)地处桂西南喀斯特地区,区内农业资源和生产水平各有差异。为了配合该地区经济的全面开发,我们收集了该地区七十一个行政乡农业生产有关的特征数据,运用数学的方法--聚类分析法和电子计算机技术,对该地区农业的空间布局进行合理调整--种植业类型区划分,并分别论述各类型区的特点及今后发展方向。为该地区今后在农业生产上做到宜地适种、扬长避短,并在此基础上向区域化、集约化的农业迈进提供科学依据。     

《西安市地图集》的总体设计与编制特征

本文论述了《西安市地图集》的总体设计与编制特征:表现多学科、多层次的研究成果,追求城市特色,突出时空动态制图,加强综合性,强化实用性,多样的表现形式和现代的制印技术。