Performance-based seismic design of integral abutment bridges   总被引：1，自引：1，他引：0  

Paolo Franchin  Paolo Emilio Pinto 《Bulletin of Earthquake Engineering》2014,12(2):939-960

Integral abutment bridges (IAB) are experiencing increasing diffusion in the short to mid-range lengths, where they offer some advantages over traditional girder bridges with non-monolithic connection at the abutments. One challenging problem with their analysis and design is that consideration of the interaction between foundation soil, structure and backfill is unavoidable, also for the deck design. Further, the end of the construction is only one of the conditions that need to be verified during design. Cyclic deformations, such as those occurring during ground shaking, typically lead to an increase in stresses in the abutments and connections, due to progressive compaction (ratcheting) of the backfill soil. This problem is magnified when the bridge is comprised between two embankments, whose response may amplify the input motion and drive the deformation of the bridge. Performance-based design aims at superseding current design procedures by explicitly checking that the target performances set out are achieved, and not overly exceeded. Such a design paradigm naturally calls, on the one hand, for improved accuracy in response determination and more refined analyses, and, on the other, for taking into account the uncertainties entering into the problem by means of an explicitly probabilistic approach. With this objective in mind, the paper presents an inelastic dynamic model for the seismic analysis and design of IABs. The model, that features a balanced compromise between the setup and evaluation effort on one hand, and accuracy on the other, has been developed for implementation in typical commercial analysis packages. It builds on 1D site-response analysis and on inelastic Winkler-like modeling, to reproduce the main physical aspects of the seismic response of IABs. One example application to a highway overpass in Italy illustrates the model and the relevance of a fully probabilistic approach to performance-based design. The application offers also important insight into the choice of an efficient intensity measure for this type of structure.  相似文献   

Evaluation of nitrate levels in groundwater under agricultural fields in two pilot areas in central Chile: A hydrogeological and geochemical approach   总被引：2，自引：0，他引：2       下载免费PDF全文

Emilio Fernández  Alejandro Grilli  Daniela Alvarez  Ramón Aravena 《水文研究》2017,31(6):1206-1224

The aim of this study is to evaluate the impact of the application of industrial fertilizers and liquid swine manure in groundwater in two pilot agricultural areas, San Pedro and Pichidegua, which have been under long‐term historic use of fertilizers. A comprehensive hydrogeological investigation was carried out to define the geology and the groundwater flow system. Chemical and isotopic tools were used to evaluate the distribution and behavior of the nitrate in the groundwater. The isotopic tools included δ¹⁸O, δ²H, and ³H, which provide information about the origin and residence time of the groundwater; δ¹⁵N‐NO₃^? and δ¹⁸O‐NO₃^?, which provide information about nitrate sources and processes that can affect nitrate along the groundwater flow system. The application rate of liquid manure and other fertilizers all together with land uses was also evaluated. The hydrogeological investigation identified the presence of a confined aquifer underneath a thick low‐permeability aquitard, whose extension covers most of the two study areas. The nitrate concentration data, excepting a few points in zones located near recharge areas in the upper part of the basins and lower areas at the valley outlets (San Pedro), showed nitrate concentration below 10 mgN/L at the regional scale. The isotope data for nitrate showed no influence of the liquid swine manure in the groundwater at the regional scale, except for the high part of the basins and the outlet of the San Pedro valley, which are areas fertilized by manure. This data showed that the regional aquifer on both pilot study areas is protected by the thick low‐permeability aquitard, which is playing an important role on nitrate attenuation. Evidence of denitrification was also found on both shallow and deep groundwater in the Pichidegua site. This study showed that a comprehensive hydrogeological characterization complemented by chemical and isotope data is key for understanding nitrate distribution and concentration in aquifers from areas with intensive agriculture activities.  相似文献   

The Role of Ex-Post and Ex-Ante Integrated Assessment Frameworks in Conceptualization of the Modeling Process in the Context of Integrated Water Resources Management     

Marzieh Samareh Hashemi  Bagheri  Ali  Rizzoli  Andrea Emilio 《Water Resources》2019,46(2):296-307

Water Resources - Reconnaissance and conceptualization of the system are the first steps to perform an integrated assessment study and step towards sustainability. This paper focuses on the...  相似文献   

Examining deforestation and agropasture dynamics along the Brazilian TransAmazon Highway using multitemporal Landsat imagery     

Guiying Li  Emilio Moran  Miquéias Freitas Calvi  Luciano Vieira Dutra  Mateus Batistella 《地理信息系统科学与遥感》2019,56(2):161-183

This research aims to understand the difference of major land-cover change results caused in various time periods and to examine the impacts of human-induced factors on land-cover changes along the TransAmazon Highway region. The Landsat Thematic Mapper and Operational Land Imager data from 2011, 2014, and 2017 and our previous land-cover classification results in 1991, 2000, and 2008 were used to examine land-cover dynamics. A classification system consisting of five land-cover classes – primary forest (PF), secondary forest (SF), agropasture (AP), urban area, and water – were chosen. The hierarchical-based classification method was used to generate land-cover classification results, and the post-classification comparison approach was used to produce detailed “from-to” conversions for each detection period. The emphasis was on deforestation of PF, dynamic change of SF and AP, and urbanization over time. The impacts of human-induced factors such as population and economic conditions on urban expansion, AP expansion, and deforestation were examined. This research indicated that selection of a suitable time period was critical for effectively detecting land-cover changes; that is, too long time period (i.e., 9 years) cannot accurately capture some land-cover changes such as the AP and SF in this research. Although deforestation – the conversion from PF to SF and AP – accounted for a large proportion of land-cover changes, the changes between SF and AP became more important than PF conversion, and required a short time period (i.e., 3 years here) for effectively reflecting their dynamics. Human-induced factors play important roles in deforestation, dynamic changes between AP and SF, and urbanization.  相似文献   

Variability of the bottom-simulating reflector (BSR) and its association with tectonic structures in the Chilean margin between Arauco Gulf (37°S) and Valdivia (40°S)     

Cristián Rodrigo  Antonio González-Fernández  Emilio Vera 《Marine Geophysical Researches》2009,30(1):1-19

Multichannel seismic reflection data recorded between Arauco Gulf (37°S) and Valdivia (40°S), on the Chilean continental margin, were processed and modeled to obtain seismic images and sub-surface models, in order to characterize the variability of the bottom-simulating reflector (BSR), which is a geophysical marker for the presence of gas hydrates. The BSR is discontinuous and interrupted by submarine valleys, canyons, as well as by faults or fractures. The BSR occurrence is more common south of Mocha Island due to moderate slopes and greater organic matter contribution by rivers in that area. Tectonic uplift and structural instability change the stability gas hydrate zone and consequently the BSR position, creating in some cases missing or double BSRs. Our modeling supports the presence of gas hydrate above the BSR and free gas below it. Higher BSR amplitudes support higher hydrate or free gas concentrations. In the study area, gas hydrate concentration is low (an average of 3.5%) suggesting disseminated gas hydrate distribution within the sediments. Also higher BSR amplitudes are associated with thrust faults in the accretionary prism, which serve as conduits for gas flow from deeper levels. This extra gas supply produces a wider thickness of gas hydrates or free gas.  相似文献   

An analog period method for gap-filling of latent heat flux measurements     

Lucas Emilio B. Hoeltgebaum  Nelson Luís Dias  Marcelo Azevedo Costa 《水文研究》2021,35(4):e14105

Practically all records of eddy-covariance flux measurements are affected by gaps, caused by several reasons. In this work, we propose analog period (AP) methods for gap-filling, and test them for filling gaps of latent heat flux at five AmeriFlux sites. The essence of the methods is to look for periods in the record that bear a strong resemblance, in the variable to be filled, to the periods immediately before and after the gap. Similarity between periods is gauged by the coefficient of determination, and the search for similar periods and their ranking is straightforward. The methods are developed in a univariate version (that uses only the latent heat flux data series itself) and several multivariate ones, that incorporate sensible heat flux, ground heat flux and net radiation data. For each set of independent variables used for gap-filling, the methods are tested against an existing gap-filling procedure with similar data requirements. Thus, the univariate version is tested against the mean diurnal variation method, and the multivariate versions are tested against corresponding simple and multiple linear regression techniques that use energy-budget data, and in one case the evaporative fraction as well. In our tests, the proposed univariate version performs better than the mean diurnal variation method, and the multivariate versions perform better than simple/multiple linear regression methods. An often used available computer package, REddyProc, was also tested as a basis of comparison. In general, the proposed methods (in univariate and multivariate versions) and simple/multiple linear regressions performed better than REddyProc. For the datasets analysed, gap filling via the evaporative fraction method performed poorly.  相似文献   

Catchment storage and residence time in a periodically irrigated watershed     

Emilio Grande  Ate Visser  Jean E. Moran 《水文研究》2020,34(14):3028-3044

Understanding anthropogenic impacts on water storage and water flow pathways in catchments is an ongoing challenge in hydrology. Here, we study the dynamics of subsurface storage and residence time of water in a catchment in Berkeley, California, that is within a regional park but contains diverse land use within its perimeter, including a periodically irrigated golf course. Our study combines several isotopic tracers with water budget data to examine sources of water in a stream draining the site. Irrigation water, applied to a small area of the watershed, is a minor component of the water budget. However, geochemical tracers reveal that irrigation water is a significant fraction of stream flow downstream of the golf course during baseflow and during precipitation events. Isotopic tracers indicate that the watershed has a preference to release young water for stream flow generation, resulting in contrasting tritium ages for stream water and groundwater of 1.3 ± 0.5 year and 8.2 ± 1.7 year, respectively. We determined that the older water is a very small component (0.7%) of the stream water in the tail of an assumed exponential distribution. We used the seasonal variation of stable water isotopes in precipitation and stream water over two water years to explain the damping of the isotopic signature of stream water, which yields information about the catchment's response to the input signal. The methods described here may be applicable to other urban or suburban headwater catchments in areas with a component of non-natural recharge from, for example, leaky infrastructure, storm water routing or dry season irrigation.  相似文献   

Brazil beyond 2020: from deforestation to the energy challenge     

Emilio Lèbre La Rovere  Carolina Burle Dubeux  Amaro Olimpio Pereira Jr  William Wills 《Climate Policy》2013,13(2):70-86

The main assumptions and findings are presented on a comparative analysis of three GHG long-term emissions scenarios for Brazil. Since 1990, land-use change has been the most important source of GHG emissions in the country. The voluntary goals to limit Brazilian GHG emissions pledged a reduction in between 36.1% and 38.9% of GHG emissions projected to 2020, to be 6–10% lower than in 2005. Brazil is in a good position to meet the voluntary mitigation goals pledged to the United Nations Framework Convention on Climate Change (UNFCCC) up to 2020: recent efforts to reduce deforestation have been successful and avoided deforestation will form the bulk of the emissions reduction commitment. In 2020, if governmental mitigation goals are met, then GHG emissions from the energy system would become the largest in the country. After 2020, if no additional mitigation actions are implemented, GHG emissions will increase again in the period 2020–2030, due to population and economic growth driving energy demand, supply and GHG emissions. However, Brazil is in a strong position to take a lead in low-carbon economic and social development due to its huge endowment of renewable energy resources allowing for additional mitigation actions to be adopted after 2020.

Policy relevance

The period beyond 2020 is now relevant in climate policy due to the Durban Platform agreeing a ‘protocol, legal instrument or agreed outcome with legal force’ that will have effect from 2020. After 2020, Brazil will be in a situation more similar to other industrialized countries, faced with a new challenge of economic development with low GHG energy-related emissions, requiring the adoption of mitigation policies and measures targeted at the energy system. Unlike the mitigation actions in the land-use change sector, where most of the funding will come from the national budgets due to sovereignty concerns, the huge financial resources needed to develop low-carbon transport and energy infrastructure could benefit from soft loans channelled to the country through nationally appropriate mitigation actions (NAMAs).  相似文献   

Roman Law and political control — from a primitive society to the dawn of the Modern World     

Emilio Biagini 《GeoJournal》1994,33(4):331-340

The purpose of this paper is to survey the history of Roman Law in order to shed light upon processes whereby society may grow more dynamic. Roman Law is the only one whose development can be traced for over thousand years, a time during which two main epochal crises brought about far-reaching changes to Roman society. The first was a consequence of the second Carthaginian war (218-200 BC), when the raw inhabitants of Latium, in a mere space of sixty years, attained supremacy over the ancient world. The second followed closely upon the death of Emperor Alexander Severus (235 AD), when the growing strength of alien populations was becoming a serious threat to the Empire.These two historical watersheds mark three different ages and three correspondingly quite different law systems that can be named: (i) the Quiritarian or strictly Roman Law, (ii) the Universal-Roman Law, (iii) the Greek-Roman Law. The legal sytem of the first epoch was suitable to a narrow rural society. The law system of the second age was suitable to the ends and values of an open civilised society. The last stage of Roman Law unfolded in the Eastern Empire, and the well-known Code of Emperor Justinian (527–29) marked the climax of this process.As a result of cautious reforms lasting several centuries, the political structures of primitive Roman society(familiae, gentes, tribus) declined, a powerful central authority was built, the nuclear family became the basic building block of society displacing extended family and clan structures, the condition of women was freed from obnoxious tutelage.Traditionally, the Roman estate of thefamilia was nearly a territorial State. Primitive buildings, often mere huts, were independent from each other. The drive to an increasingly civilised urbanisation inevitably brought about a closer spatial integration of the built-up area, and therefore made it necessary the establishment of more and more frequent praedial servitudes. To allow the organisation of urban space to emerge, the builder had to be granted a right to hold the building thus erected, for a limited time or in perpetuity, by lease or sale, against the territorial pretence of extended family or clan authority. Usucaption, pledges, mortgages, initially used in provincial lands, replaced the traditional Roman land transfer procedure(fiducia). In the time of the late Empire, slavery declined and was to some extent replaced by serfdom(colonatus). Roman citizenship was granted to all (212 AD), but the commoners(humiliores) suffered under heavy disabilities. Powerful families(honestiores) often retreated to the countryside, while the rest of the urban population was left to her own devices under an oppressive taxation system. Many luckless heads of families had to become tax proctors: they were held responsible for the gathering of taxes to the extent of their whole estate, and even on pain of torture. The State increasingly took control over most features of social and economic activity, from agriculture to the prices of foodstuffs; while individual enterprise, progress and creativity became more and more stagnant. All these are indicators of an increasingly static society. Oriental despotism became the dominant form of political organisation.Thus, while private law became more and more modernised, paving the way to the present legal systems, the social structure and the spatial organisation became more rigid and less open to innovation. Therefore a very incomplete modernisation occurred. The emergence of more open and dynamic societies was to take place many centuries after the fall of the Western Empire, precisely in the same geographical space that had belonged to it, mainly under the impulse of the more efficient and civilised among the new (Germanic) peoples (Angles, Saxons, Jutes, Franks, Longobards, etc.) who immigrated there with theVölkerwanderung and injected fresh blood into the lands of the former Western Empire, thereby ending oriental despotism. The heritage left by the evolution of Roman Law, however, was to be felt and assimilated by these peoples: it was to become a considerable part of their own cultural and legal heritage, and one of the many factors paving the way to the eventual emergence of dynamic Western societies.The age-long process of change of Roman Law can provide useful glimpses on how attitudes and cultural values not hostile to development may arise and grow to full maturity. Its study can help — though by no means alone — to understand how that part of Europe which came under its direct influence was able to achieve cultural traits open to socio-economic innovations and development.Though each social and spatial system follows its own distinctive path to development (or stagnation), some necessary cultural preconditions are broadly similar for any society. Stress upon individual values is doubtless one such inescapable precondition to the emergence of a dynamic society capable of endogenous development. Unfortunately, utterly opposite values are firmly entrenched in many Third World countries, and social evolution there is, under this viewpoint, exceedingly slow — if any.Centuries had still to elapse for individual values to prevail in Europe after the age of Justinian, and more centuries went by between the triumph of these individual values and the actual take-off stage, which only came about with the industrial revolution. Bearing in mind these facts, the inescapable conclusion arises that the apparent lack of significant cultural change leading towards a dynamic society in many countries must necessarily be a matter of the deepest concern. This is aggravated by other disquieting features of the Third World, such as the propensity to authoritarian regimes — a propensity which in its own turn is closely related to poorly developed individual values.  相似文献   

Response spectral ratios     

Emilio Rosenblueth  Alejandra Arciniega 《地震工程与结构动力学》1992,21(6):483-492

At many sites on soft ground, spectral ratios (ratios of smoothed Fourier amplitude spectral ordinates at the site to those at a station on firm ground) for distant earthquakes are little sensitive to focal mechanism and coordinates and to magnitude. Spectral ratios furnish directly expected Fourier amplitude spectral ordinates at the site of interest. The corresponding response spectra can be estimated through the use of random vibration theory. This step is obviated by resorting directly to ratios of response spectral ordinates. Through comparisons for several sites on the Valley of Mexico we find that these ratios are as stable as those of Fourier amplitude spectral ordinates.  相似文献