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.     

Aggregation of Regional Economic Time Series with Different Spatial Correlation Structures. 具有不同空间相关结构的区域经济时间序列集成

In this article, we compare the relative efficiency of different forecasting methods of space‐time series when variables are spatially and temporally correlated. We consider two cases: (1) univariate forecasting (i.e., a space‐time series aggregated into a single time series) and (2) the more general instance of multivariate forecasting (i.e., a space‐time series aggregated into a coarser spatial partition). We extend the results in the literature by including the consideration of larger datasets and the treatment of edge effects and of negative spatial correlation. We first introduce a statistical framework based on the space‐time autoregressive class of random field models, which constitutes the basis of our simulation study, and we present the various alternative forecasting methods considered in the simulation. We then present the results of a Monte Carlo study related to univariate forecasting. In order to allow a comparison with the findings of Giacomini and Granger (2004), we consider the same forecasting strategies and the same combinations of the parameter values used there, but with a larger parametric set. Finally, we extend our analysis to the case of multivariate forecasting. The outcomes obtained provide operational suggestions about how to choose between alternative forecasting methods in empirical circumstances.     

Millet microremains—an alternative approach to understand cultivation and use of critical crops in Prehistory

The term “millets” is used to identify several genera of grasses (Poaceae), most of which belong to the subfamily Panicoideae. Millets are one of the major food sources in arid and semi-arid areas of the world and they have been important crops in the prehistory of Africa and Eurasia. In this paper, we discuss phytoliths and starch grains from two of the less studied major millets (Pennisetum glaucum and Sorghum bicolor) as well as from some small millet species that are not normally considered of much importance (so-called forgotten millets: Digitaria ciliaris, Echinochloa colona, Echinochloa frumentacea, Brachiaria ramosa, Setaria pumila and Setaria verticillata). The preliminary results of this study on phytolith morphology, both at single and joined (silica skeletons) morphotypes, and starch grains show great potentials for the identification of different genus or species on the basis of microremains.     

Boundaries, Borders, and Reference Points: The Caribbean Defined as Geographic Region and Social Reality

Terms used to describe a region often reflect and directly influence the way space, identity, and history are conceived or constructed. The Caribbean is one such place where external definitions frequently transcend simple geography and socio-political boundaries. The region can be understood by both temporal and cultural categories. The case is made in this paper that archaeological interpretations of social history are impacted by how one conceives of the region.     

El co´dice ilustrado (1615/1616) de Felipe Guaman Poma de Ayala: hacia una nueva era de lectura

Guaman Poma: Writing and Resistance in Colonial Peru. Por ROLENA ADORNO. Second edition, with a new introduction. Austin: University of Texas Press, 2000. Pp. lix, 194.     

Glass and metal analyses of gold leaf tesserae from 1st to 9th century mosaics. A contribution to technological and chronological knowledge

An archaeometric study was carried out on 40 gold leaf tesserae from mosaics in Italy dated 1st to the 9th century AD. Glass layers and gold leaf were both analysed by X-ray microanalysis. The main aim was the identification of the composition of the glass and of the gold leaf, in order to assess the variations in composition and nature of the tesserae in the examined period.     

Residential segregation from the sixteenth to the nineteenth century: evidence from the Netherlands

A case study of three early modern Dutch cities (Alkmaar, Delft, and Amsterdam) using geographical information systems and confronting earlier historical, sociological, and geographical models finds clear patterns of segregation below the level of the city block, thus necessitating block-face mapping. The remarkable continuity in patterns of residential segregation is best explained by the workings of the real-estate market, allowing the well-to-do and middle classes to realize their preferences. In Amsterdam, the merchant elites were able to use their political dominance to plan a scenic and expansive residential environment free from noisy and odorous activities.