Reliability-based Strength Amplification Factors for Structures with Asymmetric Yielding

A reliability-based methodology to estimate strength amplification factors for structures with asymmetric yielding is proposed. The approach is based on structural demand hazard analyses. Nonlinear time-history analyses of tridimensional simplified systems are carried out. The effects of two orthogonal components of the seismic ground motions and soil-structure interaction, are considered. Results show that the expected ductility demand of systems with asymmetric yielding may be much higher than those of symmetric systems. A simplified mathematical expression (which is function of the ratio between the fundamental vibration period of the system and that of the soil, ductility demand, and level of asymmetric yielding) is proposed to estimate the amplification factors. The expression is applied successfully to a 9-story reinforced concrete building exhibiting asymmetric yielding produced by tilting.     

The Sandinista revolution and the limits of the Cold War in Latin America: the dilemma of non-intervention during the Nicaraguan crisis, 1977–78

This paper seeks to understand the construction of a broad alliance between the Sandinista National Liberation Front (FSLN), a socialist inspired guerrilla group, and various Latin American liberal and authoritarian governments, mainly Venezuela, Costa Rica, Panama and Cuba, between 1977 and 1979. I will seek to understand the construction of this unusual partnership, as well as the deep conflicts and mistrust that existed between the parties during the revolutionary upheaval in Nicaragua. This process will be examined by analysing the way Cold War politics and Latin American regional tensions shaped the events leading to the Sandinista revolution.     

Refining the <Emphasis Type="Italic">Maritime Foundations of Andean Civilization</Emphasis>: How Plant Fiber Technology Drove Social Complexity During the Preceramic Period

Moseley’s (1975) Maritime Foundations of Andean Civilization hypothesis challenges, in one of humanity’s few pristine hearths of civilization, the axiom that agriculture is necessary for the rise of complex societies. We revisit that hypothesis by setting new findings from La Yerba II (7571–6674 Cal bp) and III (6485–5893 Cal bp), Río Ica estuary, alongside the wider archaeological record for the end of the Middle Preceramic Period on the Peruvian coast. The La Yerba record evinces increasing population, sedentism, and “Broad Spectrum Revolution” features, including early horticulture of Phaseolus and Canavalia beans. Yet unlike further north, these changes failed to presage the florescence of monumental civilization during the subsequent Late Preceramic Period. Instead, the south coast saw a profound “archaeological silence.” These contrasting trajectories had little to do with any relative differences in marine resources, but rather to restrictions on the terrestrial resources that determined a society’s capacity to intensify exploitation of those marine resources. We explain this apparent miscarriage of the Maritime Foundations of Andean Civilization (MFAC) hypothesis on the south coast of Peru by proposing more explicit links than hitherto, between the detailed technological aspects of marine exploitation using plant fibers to make fishing nets and the emergence of social complexity on the coast of Peru. Rather than because of any significant advantages in quality, it was the potential for increased quantities of production, inherent in the shift from gathered wild Asclepias bast fibers to cultivated cotton, that inadvertently precipitated revolutionary social change. Thereby refined, the MFAC hypothesis duly emerges more persuasive than ever.     

The Survival of Words: Revolution and Class Struggle

How did Kirchnerismo, initially a motley coalition of progressive Peronists and born-again Menemistas and Duhaldistas trying to scrape together some form of governability from the 2001 default, turn into one of the ‘pink tide’ governments most virulently hated by the Right? Why did long-forgotten concepts and terminologies from the epic past of revolutionary struggle suddenly resurface in the context of what, at least from the viewpoint of the autonomist Left, was hardly more than a mildly redistributive administration of scarcity, aided by the post-millennial commodity boom? In this intervention, historian Javier Trímboli urges us to take seriously some of the discursive anachronisms that flourished during Néstor and Cristina Kirchner’s periods in office (2003–2015), which, he suggests, rather than merely a form of discursive cover for clientelist politics, may have been symptomatic of the way in which some of the foundational fault-lines of modern Argentine society continue to shape political identities, styles and forms of struggle in the present.     

Letting skeletons out of the closet: the ethics of displaying ancient Mexican human remains

In the wake of Native North American activism and moves to decolonize archaeology, some academics have begun to avoid displaying human remains. Though recent World Archaeological Congress accords detail a consent process for ethical display, some journals, museums, and individual scholars have blanket policies covering even those remains whose descendants favour display. This article examines one context affected by these policies: the central Mexican town of Xaltocan. Here, Indigenous residents advocate for archaeological study and exhibition of ancient human remains, yet they have been criticised and censored by North American audiences. We consider two factors behind their desire to display the dead as part of efforts to reclaim Indigenous identities: long-standing Mesoamerican relationships with the dead and the materiality and symbolic capital of bones. We argue that an academic reluctance to display any human remains is problematic – even if it is a well-intentioned acknowledgement of respect for their sensitive nature – because it imposes the wishes of one Indigenous group on another, and may thereby lead to the unwitting perpetuation of colonial practice. We suggest that decolonizing archaeology may sometimes necessitate allowing the exhibition of skeletal remains; ethnographic research in individual communities is needed to ensure respect for descendant perspectives.     

In situ desalination of a granitic column by the electrokinetic method

Desalination of rocks used in monuments is a common strategy to reduce the possibility of deterioration by soluble salt crystallization processes. In the last years, some laboratory studies have demonstrated that the application of electrokinetic techniques allow to achieve higher desalination effectiveness, overcoming most limitations of the traditional methods. However, to our knowledge no studies have been conducted on the effectiveness of this technique for in situ desalination of granite. The present study is aimed at filling this gap. The results of an in situ desalination intervention using electrokinetic methods, on a column highly contaminated with salts are presented. The desalination method was optimized to desalinate large in situ structures, trying to establish the necessary protocols (buffering system, irrigation system, setup, etc.) to obtain results as satisfactory as those obtained in laboratory. The results demonstrated the high effectiveness of this method in terms of total salt extraction and depth of salt extraction. The concentration of anions in the column was decreased by more than 80% after 55 days of treatment. No mineralogical and aesthetic damages on the stone were detected after the treatment, confirming the reliability of this method to be applied in situ on granitic rocks.     

Chemical durability of lead-bearing glazes in sulphuric acid solutions — Laboratory experiments performed on Zsolnay architectural ceramics from Budapest (Hungary)

This study aims to simulate the long-term deterioration of architectural glazes exposed to open air in a highly polluted urban environment. A laboratory experiment—a 14-day long accelerated weathering test—on glazed roof tiles has been performed to reveal the damaging influence of contacting acid solutions originating from dissolved gaseous pollutants, mainly SO₂. The studied tiles are made by the Hungarian Zsolnay factory and applied on two buildings in Budapest in the 19th and 20th century. The ceramics were covered mainly by lead glazes in the construction and lead-bearing alkali glazes in the renovation periods.

The solution of pH2 induced a greater dissolution, especially of alkali and alkaline earth metals (up to 2886 ppm), but less lead (up to 21 ppm) from the lead glazes of the construction periods. Newly formed lead sulphate (anglesite) on the corroded glaze parts precipitated on some lead-bearing alkali glazes, with moderate dissolution of alkali and alkaline earth metals (up to 396 ppm) accompanied by higher amount of lead (28–39 ppm). Based on the results, the main determining factor in the durability of glazes is mostly their chemical composition and less their preliminary degradation state.     

Accuracy evaluation of the semi-automatic 3D modeling for historical building information models

It is stated that 3D recording and modeling of heritage buildings entail accurate building models (as-built). However, this paper presents an analysis of the 3D modeling accuracy for the creation of historical building information models (HBIM), considering the complexity and the deformations of historical buildings, using point cloud data and BIM tools. The 3D modeling processes analyzed are based on a three-stage semi-automatic approach leading to the generation of HBIM, including manual and automatic processes. The three stages consist of: (a) optical and terrestrial laser scanning; (b) meshing processes; and finally (c) 3D solid modeling to be assembled into HBIM. Next, this approach analyzed the mesh deformations generated automatically in comparison to the initial point cloud data. The deformations and the accuracy evaluation have been undertaken using different commercial software. Finally, our modeling approach shows that it can improve the accuracy of the 3D models achieved using existing BIM technologies.