Seismic reliability of structures equipped with LIR-DCFP bearings in terms of superstructure ductility and isolator displacement

This research deals with the seismic reliability of non-linear base-isolated structures equipped with Lateral Impact Resilient Double Concave Friction Pendulum (LIR-DCFP) devices. Specifically, exceeding probabilities within the reference lifetime are assessed with respect to both superstructure ductility and isolator displacement demand. The innovative LIR-DCFP bearing has an improved inner slider with an internal gap and is capable to reduce adverse effects of the lateral impact between the inner slider and the restraining rims. The dynamic behavior of the superstructure is represented by a simplified one-degree-of-freedom model describing its lateral response. The isolation system is characterized by a model based on rigid body dynamics also including the lateral impact behavior. A wide parametric analysis is developed for several system properties considering the friction coefficients as relevant random variables. Different sets of natural seismic records able to match conditional spectra for a site in Riverside (California) were selected to consider the aleatory uncertainties of the seismic input. Incremental dynamic analyses were performed to determine the statistics of significant engineering demand parameters and compute probabilities exceeding specific limit states to define fragility curves. Finally, employing seismic hazard curves, the seismic reliability of isolated structures was evaluated. For increasing values of the internal gap, structures equipped with LIR-DCFP devices exhibit better seismic performance with respect to classical DCFP bearings with same size, especially, if the superstructure is designed to behave essentially elastic when the lateral capacity of the isolation level is not reached, or the hardening post-yield stiffness of the superstructure is relatively high. Reductions up to 20% in the exceeding probabilities within 50 years related to the ductility demand are achievable using the suggested LIR-DCFP isolator

Comparative seismic performance of a moment frame equipped with Lateral Impact Resilient Double Concave Frictional devices

This study presents a comparative assessment of the seismic performance of a reinforced concrete moment frame equipped with a new isolator. The Lateral Impact Resilient Double Concave Friction Pendulum (LIR-DCFP) bearing has an enhanced inner slider capable of limiting the magnitude of the lateral impact force generated between the inner slider and the restraining rims of the sliding surfaces. Due to the presence of a plane high-friction interface with an internal gap, the novel isolator has an increased energy dissipation capacity that is activated during the lateral impact. Three isolation systems were considered to evaluate the benefits of using LIR-DCFP devices. One conformed by the suggested isolator, and two composed of classic non-articulated Double Concave Friction Pendulum (DCFP) bearings. The isolation devices were modelled employing a numerical formulation based on rigid body dynamics, capable of accounting for the lateral impact behaviour. The superstructure, a reinforced concrete moment resisting frame designed according to the American ASCE/SEI 7-16 standard, was modelled using beam-column elements considering geometric and material nonlinearities. Furthermore, the degrading behaviour of the building was incorporated using a proper degradation model for both the stiffness and the force. Incremental Dynamic Analyses (IDAs) were performed considering the friction coefficient as a random variable to characterize the statistics of the maximum inter-story responses. With the data generated in the IDAs, fragility curves related to the superstructure performance were constructed. Finally, employing the hazard curve, reliability curves were derived. The superstructure equipped with LIR-DCFP bearings presents better seismic performance than the same building equipped with the same size DCFP isolators. The benefits of using the new isolator are not achieved by increasing the lateral capacity of the classic isolation system

STATIC AND DYNAMIC EXPERIMENTAL VALIDATIONS OF THE LATERAL IMPACT RESILIENT DOUBLE CONCAVE FRICTION PENDULUM (LIR-DCFP) BEARING

During high-magnitude earthquakes, large base displacements that exceed the lateral capacity of the isolation level can cause internal impacts jeopardizing the benefits of using seismic isolation. The Lateral Impact Resilient Double Concave Friction Pendulum (LIR-DCFP) bearing has been proposed to mitigate the adverse effects of internal lateral impacts between inner sliders and restraining rims of sliding surfaces. This device has an enhanced inner slider formed by two bodies. These bodies are in contact, generating a plane high-friction interface capable of dissipating additional energy and limiting the magnitude of the impact. A numerical model based on rigid body dynamics has been proposed to represent the dynamic response of structures equipped with LIR-DCFP bearings. The numerical formulation includes important modeling aspects such as lateral impact behavior and large displacements (P-? effects), among other essential phenomena. A prototype of this novel device was constructed to validate its lateral behavior through static experimental tests. As predicted, if the inner slider does not contact the restraining rims of the sliding surfaces, the response of the isolator will be identical to the response of the classical frictional isolators. On the contrary, for larger lateral displacements, the contact between the inner slider and the restraining rims triggers high friction sliding. Finally, experimental tests were conducted to validate the dynamic response of a stiff structure equipped with four LIR-DCFP devices. An accurate prediction of the dynamic response can be obtained by employing the suggested numerical model under the presence or absence of internal lateral impacts

Towards a flourishing blue economy: Identifying obstacles and pathways for its sustainable development

The current discourse addressing the need for sustainable development in the blue economy is necessary to promote effective mitigation and adaptation responses in times of rapid climate change. However, thus far, said discourse lacks foundational and specific principles to provide critical pillars able to shed light on socio-economic processes needed to achieve sustainable development across sectors and scales. This article discusses ten recently-described nature-based principles for achieving and sustaining a regenerative blue economy while advocating for an age of factuality. These scientifically-derived principles are built on well-accepted concepts of socio-ecological system dynamics and undergird a healthy blue economy

A dynamic management framework for socio-ecological system stewardship: A case study for the United States Bureau of Ocean Energy Management

An effective and efficient stewardship of natural resources requires consistency across all decision-informing approaches and components involved, i.e., managerial, governmental, political, and legal. To achieve this consistency, these elements must be aligned under an overarching management goal that is consistent with current and well-accepted knowledge. In this article, we investigate the adoption by the US Bureau of Ocean Energy Management of an environmental resilience-centered system that manages for resilience of marine ecological resources and its associated social elements. Although the framework is generally tailored for this Bureau, it could also be adapted to other federal or non-federal organizations. This paper presents a dynamic framework that regards change as an inherent element of the socio-ecological system in which management structures, e.g., federal agencies, are embedded. The overall functioning of the management framework being considered seeks to mimic and anticipate environmental change in line with well-accepted elements of resilience-thinking. We also investigate the goal of using management for resilience as a platform to enhance socio-ecological sustainability by setting specific performance metrics embedded in pre-defined and desired social and/or ecological scenarios. Dynamic management frameworks that couple social and ecological systems as described in this paper can facilitate the efficient and effective utilization of resources, reduce uncertainty for decision and policy makers, and lead to more defensible decisions on resources

How will Mahanarva spectabilis (Hemiptera: Cercopidae) respond to global warming?

The aim of this study was to determine the favorable constant temperature range for Mahanarva spectabilis (Distant) (Hemiptera: Cercopidae) development as well as to generate geographic distribution maps of this insect pest for future climate scenarios. M. spectabilis eggs were reared on two host plants (Brachiaria ruziziensis (Germain and Edvard) and Pennisetum purpureum (Schumach)), with individual plants kept at temperatures of 16, 20, 24, 28, and 32C. Nymphal stage duration, nymphal survival, adult longevity, and egg production were recorded for each temperature*host plant combination. Using the favorable temperature ranges for M. spectabilis development, it was possible to generate geographic distribution. Nymphal survival was highest at 24.4C, with estimates of 44 and 8% on Pennisetum and Brachiaria, respectively. Nymphal stage duration was greater on Brachiaria than on Pennisetum at 20 and 24C but equal at 28C. Egg production was higher on Pennisetum at 24 and 28C than at 20C, and adult longevity on Pennisetum was higher at 28C than at 20C, whereas adult longevity at 24C did not differ from that at 20 and 28C. With these results, it was possible to predict a reduction in M. spectabilis densities in most regions of Brazil in future climate scenarios

Terceiro e quarto relatórios de avaliação do IPCC: comparação entre cenários futuros de distribuição geográfica do Sipha flava no Brasil.

O trabalho visou comparar os resultados da distribuição geográfica do Sipha flava com base no Terceiro e no Quarto Relatório de Avaliação do IPCC no território brasileiro. O afídeo apresenta ampla distribuição geográfica, e pode causar danos às diversas culturas utilizadas na alimentação do gado de leite. As imagens que contém as médias de temperatura com tamanho de 30? (meio grau) cada pixel, dos relatórios do IPCC foram classificadas de acordo com as faixas de temperatura de sobrevivência do inseto, realizadas em laboratório por Oliveira et al. (2009), assim foi possível gerar o cenário A2 para os anos 2020, 2050 e 2080 (cenário em que o aquecimento traria modificações drásticas para o clima) com base no Quarto Relatório (IPCC, 2007). O software ArcGIS foi utilizado na confecção dos mapas para o Quarto Relatório. A comparação dos mapas para os relatórios em questão mostrou que em termos de regiões, a favorabilidade continua com a mesma tendência para os meses de temperaturas médias mais altas no ano de 2020, mas com algumas modificações nos estados abrangidos. Observa-se um aumento das áreas não favoráveis nos anos de 2050 e 2080 nas regiões Norte, Nordeste e Centro-Oeste

Humoral immune response of pregnant goats to two Corynebacterium pseudotuberculosis bacterin formulations

Caseous lymphadenitis is a chronic suppurative bacterial disease caused by Corynebacterium pseudotuberculosis, and it has a high prevalence among small ruminants. Different vaccine preparations have been employed to control this disease. The adjuvant used in the formulation is a critical factor for the improvement of vaccine efficacy. No commercial vaccines are available in Argentina. The aims of the present work were to compare the specific antibody response against a C. pseudotuberculosis whole cell vaccine formulated with a classical and an immunoestimulant adjuvant in pregnant goats, and to assess the transfer of vaccine-specific antibodies from the goat to the offspring through colostrum. Twenty three pregnant goats were vaccinated. The animals were randomly allocated to three groups: control, aluminum hydroxide Al(OH)3 adjuvant and a new cage-like particle adjuvant (ISPA). Antibodies (IgG) against this antigen were measured by ELISA. A robust humoral immune response was detected in vaccinated animals, with production of specific IgG. No significant differences were found between the vaccines formulated with different adjuvants. High levels of specific antibodies were detected in colostrum samples from both immunised groups, which were passively transferred from goats to offprings. No adverse local reactions in the vaccines injection sites were detected