Practical aspects of demand and capacity evaluation of RC members in the context of EC8‐3

The structural safety assessment procedures proposed in Part 3 of Eurocode 8 (EC8‐3) for the case of reinforced concrete structures are addressed. The practical evaluation of the member chord rotation demand according to EC8‐3 is examined in detail along with several alternative formulations. The need for these formulations is demonstrated by presenting example situations where the EC8‐3 proposal is difficult to apply. The effectiveness of the proposed approaches is assessed through an example application and recommendations for their practical use are defined. Given the importance of the shear span in this context, a sensitivity analysis of the EC8‐3 capacity models with respect to this parameter is carried out and discussed in a later section. This analysis aims to assess the validity of the simplifications proposed by a previous research study for the quantification of the EC8‐3 capacity values. Copyright © 2009 John Wiley & Sons, Ltd.     

Central Configurations of the Symmetric Restricted 4-Body Problem

We consider the symmetric planar (3 + 1)-body problem with finite masses m ₁ = m ₂ = 1, m ₃ = µ and one small mass m ₄ = . We count the number of central configurations of the restricted case = 0, where the finite masses remain in an equilateral triangle configuration, by means of the bifurcation diagram with as the parameter. The diagram shows a folding bifurcation at a value consistent with that found numerically by Meyer [9] and it is shown that for small > 0 the bifurcation diagram persists, thus leading to an exact count of central configurations and a folding bifurcation for small m ₄ > 0.     

Mixing Methodologies in Seismic Hazard Assessment via a Logic Tree Procedure: An Application for Eastern Spain

This study provides a procedure for assessing seismic hazardand uncertainties in regions that are characterised by a large non-instrumental earthquakedatabase and a seismic and tectonic behaviour which doesn't allow an evident seismic zonation.This procedure is a synthesis of the non-zoning or non-parametric methodology (using extremevalues distribution functions as proposed by Epstein and Lomnitz, 1966) and the zoning orparametric methodology (using the theorem of total probability as proposed by Cornell, 1968)via a logic tree procedure taking into consideration the advantages offered by each of these.Taking the area which we shall describe as the east coast of Spain and surrounding inland areas,an application was made and a specific logic tree was developed in order to solve the problems anduncertainties related to the evaluation of the seismic hazard using both methodologies. The use of thelogic tree allowed the systematisation of a large number of solutions obtained. A number of relevantresults were obtained which show that in some cases there are great differences in the seismichazard results provided by the non-zoning and the zoning methodologies. In these cases, mean value andstandard deviation of the obtained results provide an intermediate solution to the over-conservativeestimation provided by the non-zoning methodology and the lowest results provided by the zoningmethodology. In other cases results provided by both methodologies are significantly closer.In any case, synthesis among both methodologies gives a wider knowledge of the uncertaintiesassociated with the seismic hazard results. Finally uncertainties increase with the decreaseof the annual probability of exceedence and in sites with a seismic history of large size earthquakes.     

Overheated, Cu-bearing magmas in the Zaldívar porphyry-Cu deposit, Northern Chile. Geodynamic consequences

The Zaldívar porphyry copper deposit, Northern Chile, consists of two major intrusions, the 290 Ma Zaldívar, and the more recent Miocene (38.7 Ma) Llamo porphyry. Five types of inclusions have been identified in quartz phenocrysts from Llamo porphyry, including melt inclusions (M), and four types of fluid inclusions, called MS (multi solids), B (brines), G (vapor-rich) and W (aqueous), respectively.Melt remnants, well preserved as M-inclusions, homogenize around 1000 °C. They show a rhyolitic composition, comparable to the most evolved acidic rhyolitic end member found elsewhere in the regional magmatism and to worldwide volcanic rhyolitic glass. High silica content in some inclusions can, however, be due to partial remelting of the quartz host during the heating run. Copper content in the same inclusions ranges between 0.03 and 0.57 wt.%, with an average concentration of 0.10 wt.%, suggesting a major magmatic source for the copper (orthomagmatic model).MS inclusions, which contain a number of solids at room temperature, mostly H₂O-bearing phases (system NaCl–KCl–((Fe, Mg, Cu)Cl)–H₂O, average salinity 70 wt.% NaCl equiv.), homogenize at magmatic temperatures (around 1000 °C). They represent the first fluids to have exsolved from the magma at depth, at a pressure of about 2 kbar. Their high homogenization temperature, comparable to values measured for melt inclusions (1000 to 1050 °C), may indicate trapping of MS and M inclusions in host phenocrysts from an immiscible mixture of silicate melt and highly saline fluids expelled from the magma during the early stage of quartz crystallization.The data indicate a magmatic origin for copper, as well as extremely high melt temperatures. These features are interpreted by magmatic differentiation of mantle-derived primitive melts, corresponding to major changes in the tectonic regime of the Andean margin, which occurred in Miocene times.     

Structure of the Padul-Nigüelas Basin (S Spain) from H/V Ratios of Ambient Noise: Application of the Method to Study Peat and Coarse Sediments

—?This paper presents the results of the application of a technique of geophysical surveying based on resonance frequency of materials, in a small basin within the Internal Zones of the Betic Cordillera (southern Spain). The frequencies determined have enabled the main features of the basin's structure to be delineated, clearly identifying its asymmetry due to variations in the position of the rigid basement in different sectors. The results show that this method does not guarantee a perfect identification of coarse sediments, unless these overlie substantial more rigid materials. On the other hand, the same method was very effective for studying very soft sediments (peat), and it was possible to establish a quantitative relationship for determining the thickness of these sediments based on their resonance frequency. This relationship was then used to map peat thickness in the basin. The results have been compared with gravity studies and mechanical drillings undertaken in the region.     

Sediment budget controls on foredune height: Comparing simulation model results with field data

The form, height and volume of coastal foredunes reflects the long‐term interaction of a suite of nearshore and aeolian processes that control the amount of sand delivered to the foredune from the beach versus the amount removed or carried inland. In this paper, the morphological evolution of more than six decades is used to inform the development of a simple computer model that simulates foredune growth. The suggestion by others that increased steepness of the seaward slope will retard sediment supply from the beach to the foredune due to development of a flow stagnation zone in front of the foredune, hence limiting foredune growth, was examined. Our long‐term data demonstrate that sediment can be transferred from the beach to the foredune, even with a steep foredune stoss slope, primarily because much of the sediment transfer takes place under oblique rather than onshore winds. During such conditions, the apparent aspect ratio of the dune to the oncoming flow is less steep and conditions are not as favourable for the formation of a stagnation zone. The model shows that the rate of growth in foredune height varies as a function of sediment input from the beach and erosion due to storm events, as expected, but it also demonstrates that the rate of growth in foredune height per unit volume increase will decrease over time, which gives the perception of an equilibrium height having been reached asymptotically. As the foredune grows in size, an increasing volume of sediment is needed to yield a unit increase in height, therefore the apparent growth rate appears to slow. Copyright © 2018 John Wiley & Sons, Ltd.     

Can PAHs influence Cu accumulation by salt marsh plants?

The presence of polycyclic aromatic hydrocarbons (PAHs) may change the mechanisms of metal uptake, thus influencing kinetics and extent of metal phytoextraction. Studies on the subject are scarce, particularly for salt marsh plants. The aim of this work was to investigate the effect of PAHs on the uptake of Cu by Halimione portulacoides, a plant commonly found in salt marshes. Experiments were carried out in the laboratory, either in hydroponics (sediment elutriate) or in sediment soaked in elutriate, which were prepared with sediment and water from a salt marsh of the Cavado river estuary (NW Portugal). Groups of H. portulacoides (grown in a greenhouse) were exposed to those media during six days. Cu(2+) (as Cu(NO(3))(2)), 10(2) and 10(4)mugl(-1), was added to the media as well as 1.6mugl(-1) of the sixteen EPA priority PAHs (0.1mugl(-1) of each PAHs). Cu was assayed in solutions, sediments and different plant tissues before and after experiments. After exposure, photosynthetic efficiency and levels of chlorophylls were also measured, indicating that plant stress indicators were identical in all plants independently of the media to which the plants were exposed. PAHs influenced both the soluble Cu fraction and Cu uptake by plants. The amounts of metal accumulated in both roots and stems were significantly higher when the 10(4)mugl(-1) of Cu enriched elutriate was amended with PAHs. Thus, results suggest that PAHs may modify Cu solubility, the Cu sorption by plants and/or the passive penetration of Cu into the root cells. Therefore, the combined effects of different types of pollutants should be taken in consideration when studying the remediation potential of plants, namely in terms of phytoextraction.     

Late Holocene marine terraces of the Cartagena region,southern Caribbean: The product of neotectonism or a former high stand in sea-level?

The detailed stratigraphic survey and paleontological study (mollusks, corals, foraminifera and ostracods) of four low-level, ～3 m, marine terrace sections: Punta Canoas, Manzanillo del Mar, Playa de Oro, and Tierra Bomba Island, from the Cartagena region, southern Caribbean, supplemented with 22 radiocarbon dates, reveals that the northern terraces were deposited as parasequences in a clastic depositional system compared to the Tierra Bomba Island succession that was deposited in a carbonate depositional system between ～3600 and ～1700 cal yrs BP. Drier conditions and the southern location of the ITCZ at about 3 ka triggered stronger easterly Trades and more dynamic southwestward sediment drift fed by the Magdalena River mouth, thus promoting the formation of sand spits that ultimately isolated the Cienaga de Tesca coastal lagoon from the Caribbean Sea. Our estimates support the hypothesis that the present position of the terraces is the product of neotectonism rather than a higher 3 ka, sea-level. Upheaval of the terraces varies between ～3.8 mmyr^?1 at Punta Canoas and ～2.2 mmyr^?1 at Tierra Bomba to ～1.5 mmyr^?1 at Manzanillo del Mar and Playa de Oro terraces. Our study corroborates previous contentions on the role of mud diapirism and the dynamics of the Dique Fault as late Holocene upheaval mechanisms.     

Potential for growing Arabica coffee in the extreme south of Brazil in a warmer world

Agriculture appears to be one of the human activities most vulnerable to climatic changes due to its large dependence on environmental conditions. However, the diversity of Brazilian environmental conditions could be of great advantage to adapting this sector to new climatic conditions, which should be assessed as in this study on shifting Arabica coffee cultivation to the extreme south of the country. The methodology applied is the same the one used to define climatic risks in current productive regions of Brazil and their vulnerability to climatic change predicted by IPCC reports. The basic climatic parameters applied were frost probability and annual average temperature, since annual water deficit did not prove to be a restricting factor for Arabica coffee cultivation in the study area. The climatic conditions suitable for coffee production are: annual average temperature between 18??C and 22??C, annual water deficit less than 100?mm and frost probability (risk of lowest annual temperature less than 1??C) less than 25%. An area is said to have ??low climatic risks?? for coffee production when these three climatic conditions are met. Current climatic conditions were used and simulations of four temperature increases between 1??C and 4??C were also performed. The results indicated a substantial increase in the size of low climatic risks areas for the production of Arabica coffee in the extreme south of Brazil, mainly for mean temperature increases of 3??C in the study area in relation to present conditions. Increases of 2??C and 4??C were also favorable, but not as good as those obtained for 3??C. It should be underscored that areas with low climatic risks will be able to be found mainly in the extreme south of the study region, the border with Uruguay and North of Argentina.