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排序方式: 共有173条查询结果,搜索用时 15 毫秒
31.
Gaetano Manfredi Andrea Prota Gerardo Mario Verderame Flavia De Luca Paolo Ricci 《Bulletin of Earthquake Engineering》2014,12(5):2275-2298
Data of the Italian National Institute of Statistics are collected aimed at characterizing Reinforced Concrete (RC) building stock of the area struck by the 2012 Emilia earthquake (number of storeys, age of construction, structural typology). Damage observations, collected right after the event in reconnaissance reports, are shown and analyzed emphasizing typical weaknesses of RC buildings in the area. The evolution of seismic classification for Emilia region and RC buildings’ main characteristics represent the input data for the assessment of non-structural damage of infilled RC buildings, through a simplified approach (FAST method), based on EMS-98 damage scale. Peak Ground Acceleration (PGA) capacities for the first three damage states of EMS-98 are compared with registered PGA in the epicentral area. Observed damage and damage states evaluated for the PGA of the event, in the epicentral area, are finally compared. The comparison led to a fair agreement between observed and numerical data. 相似文献
32.
Brian W. Zimmer Nancy R. Riggs Gerardo Carrasco-Núñez 《Bulletin of Volcanology》2010,72(10):1223-1240
Cerro Pinto is a Pleistocene rhyolite tuff ring-dome complex located in the eastern Trans-Mexican Volcanic Belt. The complex
is composed of four tuff rings and four domes that were emplaced in three eruptive stages marked by changes in vent location
and eruptive character. During Stage I, vent clearing produced a 1.5-km-diameter tuff ring that was then followed by emplacement
of two domes of approximately 0.2 km3 each. With no apparent hiatus in activity, Stage II began with the explosive formation of a tuff ring ~2 km in diameter adjacent
to and north of the earlier ring. Subsequent Stage II eruptions produced two smaller tuff rings within the northern tuff ring
as well as a small dome that was mostly destroyed by explosions during its growth. Stage III involved the emplacement of a
0.04 km3 dome within the southern tuff ring. Cerro Pinto’s eruptive history includes sequences that follow simple rhyolite-dome models,
in which a pyroclastic phase is followed immediately by effusive dome emplacement. Some aspects of the eruption, however,
such as the explosive reactivation of the system and explosive dome destruction, are more complex. These events are commonly
associated with polygenetic structures, such as stratovolcanoes or calderas, in which multiple pulses of magma initiate reactivation.
A comparison of major and trace element geochemistry with nearby Pleistocene silicic centers does not show indication of any
co-genetic relationship, suggesting that Cerro Pinto was produced by a small, isolated magma chamber. The compositional variation
of the erupted material at Cerro Pinto is minimal, suggesting that there were not multiple pulses of magma responsible for
the complex behavior of the volcano and that the volcanic system was formed in a short time period. The variety of eruptive
style observed at Cerro Pinto reflects the influence of quickly exhaustible water sources on a short-lived eruption. The rising
magma encountered small amounts of groundwater that initiated eruption phases. Once a critical magma:water ratio was exceeded,
the eruptions became dry and sub-plinian to plinian. The primary characteristic of Cerro Pinto is the predominance of fall
deposits, suggesting that the level at which rising magma encountered water was deep enough to allow substantial fragmentation
after the water source was exhausted. Isolated rhyolite domes are rare and are not currently viewed as prominent volcanic
hazards, but the evolution of Cerro Pinto demonstrates that individual domes may have complex cycles, and such complexity
must be taken into account when making hazard risk assessments. 相似文献
33.
Gerardo Bocco Angel Priego Helena Cotler 《Singapore journal of tropical geography》2010,31(2):215-223
In recent years, physical geography in Mexico has contributed to the enterprise of geographical science by integrating with fields of study closely related to topics of sustainable development. This paper outlines the contribution of the discipline to environmental public policy development, particularly ecological land use planning and integrated watershed management. In terms of applications, physical geography appears to have reached a stage of maturity in Mexico. However, it must offer a stronger leadership in areas such as ecoregional analysis (in an integrated fashion, and not only from the biological‐ecological perspective) and regional vulnerability to global change processes. An excellent opportunity exists for scientists and decision makers to develop a common agenda. 相似文献
34.
35.
Procedures for calibration of linear models for damage limitation in design of masonry‐infilled RC frames
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Paolo Ricci Maria Teresa De Risi Gerardo Mario Verderame Gaetano Manfredi 《地震工程与结构动力学》2016,45(8):1315-1335
Recent earthquakes have confirmed the role played by infills in the seismic response of reinforced concrete buildings. The control and limitation of damage to such nonstructural elements is a key issue in performance‐based earthquake engineering. The present work is focused on modeling and analysis of damage to infill panels, and, in particular, it is aimed towards linear analysis procedures for assessing the damage limitation limit state of infilled reinforced concrete frames. First, code provisions on infill modeling and acceptance criteria at the damage limitation limit state are reviewed. Literature contributions on damage to unreinforced masonry infill panels and corresponding displacement capacity are reported and discussed. Two procedures are then proposed aiming at a twofold goal: (i) the determination of ‘equivalent’ interstory drift ratio limits for a bare frame model and (ii) the estimation of the stiffness of equivalent struts representing infill walls in a linear model. These two quantities are determined such that a linear model ensures a reliable estimation of seismic capacity at the damage limitation limit state, providing the same intensity level as that obtained from nonlinear analyses carried out on structural models with infills. Finally, the proposed procedures are applied to four‐story and eight‐story case study‐infilled frames, designed for seismic loads according to current technical codes. The results of these application examples are presented and discussed. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
36.
37.
Kowalski Andrew S. Serrano-Ortiz Penélope Miranda-García Gabriela Fratini Gerardo 《Boundary-Layer Meteorology》2021,179(3):347-367
Boundary-Layer Meteorology - An analysis based on the law of linear momentum conservation demonstrates unequivocally that the mass fraction is the scalar whose gradient determines gas diffusion,... 相似文献
38.
Noreña-Barroso E Simá-Alvarez R Gold-Bouchot G Zapata-Pérez O 《Marine pollution bulletin》2004,48(3-4):263-269
Livers of catfish (Ariopsis assimilis) from the Bay of Chetumal were analyzed for organochlorine compounds and hydrocarbons as part of a study to diagnose the environmental health of the Bay after a catfish mass mortality that occurred in 1996. The presence of histological lesions in several organs of the fish as result of chemical exposure was also evaluated. The concentrations of organic pollutants found in the Bay may be considered high if compared to the levels reported for sites affected by chemical pollution. High prevalences of cellular alteration histopathologies were found in liver, including hepatic tumors. The presence of some lesions may be related statistically to environmental pollution in the Bay, specially with chlorinated compounds. 相似文献
39.
Costa Rica is located geographically in the southern part of the Central American Volcanic Front, a zone where interaction between the Mesoamerican and South American cultures occurred in pre-Columbian times. Several volcanoes violently erupted during the Holocene, when the first nomadic human hunters and later settlers were present. Volcanic rocks were the most important geo-resource in making artifacts and as construction materials for pre-Columbian inhabitants. Some pottery products are believed to resemble smoking volcanoes, and the settlements around volcanoes would seem to indicate their influence on daily life. Undoubtedly, volcanic eruptions disrupted the life of early settlers, particularly in the vicinity of Arenal and Irazú volcanoes, where archaeological remains show transient effects and displacement caused by periodical eruptions, but later resilient occupations around the volcanoes. Most native languages are extinct, with the exception of those presently spoken in areas far away from active volcanoes, where no words are related to volcanic phenomena or structures. The preserved legends are ambiguous, suggesting that they were either produced during the early Spanish conquest or were altered following the pre-Columbian period. 相似文献
40.
Cholinesterase inhibition is considered a specific biomarker of exposure and effect for organophosphorous pesticides. Its use for monitoring has been hindered, particularly in tropical countries where organophosphates are widely used for malaria and dengue control, because of the frequent lack of suitable controls. An in vitro technique is proposed as a biochemical method for monitoring pollutant mixtures in sediment toxicity tests. Brain homogenate from the fish Oreochromis niloticus is used as the enzyme source. Optimum incubation time, extraction solvent and effect of crude oil on acetylcholinesterase (AChE) are reported. The method described was used in sediments from two Mexican lagoons, located in an oil extraction area where pesticides are used in agriculture and vector control campaigns. AChE inhibitions from 3 to 21% were found in these lagoons, even in the presence of high concentrations of petroleum. 相似文献