scholarly journals Preliminary Evaluation of the Impact of Eurocode 8 Draft Revision on the Seismic Zonation of Romania

2022 ◽  
Vol 12 (2) ◽  
pp. 649
Author(s):  
Florin Pavel ◽  
Radu Vacareanu ◽  
Kyriazis Pitilakis
Keyword(s):  
Control Period ◽  
Response Spectra ◽  
Eurocode 8 ◽  
Preliminary Evaluation ◽  
Seismic Zonation ◽  
Seismic Safety ◽  
Seismic Code ◽  
Local Soil ◽  
The Impact ◽  
Maximum Design

This study is focused on the impact of the Eurocode 8 draft revision on the seismic zonation of Romania, one of the countries with the highest hazard levels in Europe. In this study, the design response spectra are evaluated for a number of sites in Romania for which both shear wave velocity profiles and ground motion recordings are available. The impact of the proposed changes on the structural design for structures situated in the southern part of Romania is also discussed. The results show considerable differences between the design response spectra computed according to the Eurocode 8 draft revision and the design response spectra from the current Romanian seismic code P100-1/2013. The differences are larger in the case of the sites situated in the southern part of Romania and those which have large design values for the control period TC. In Bucharest, for instance, it was found that the maximum design spectral accelerations would correspond to those from the 2006 version of the code while the maximum design spectral displacements would be significantly smaller than the levels produced by the 1981 or 1992 versions of the code. The results presented herein show that the differences in the seismic hazard and design ground motions are mainly due to the effects of local soil and site conditions and the associated site amplification proposed in the current Romanian seismic code and EC8 draft revision. Moreover, it has been shown that more analyses are needed to apply the seismic actions proposed in Eurocode 8 revision specifically for the sites in Romania under the influence of Vrancea intermediate-depth earthquakes so as to ensure an increased level of seismic safety for structures designed and built in the future.

scholarly journals Vertical to Horizontal UHS Ratios for Low to Medium Seismicity Regions with Deep Soil atop Deep Geological Sediments—An Example of the City of Osijek, Croatia

2021 ◽  
Vol 11 (15) ◽  
pp. 6782
Author(s):  
Borko Đ. Bulajić ◽  
Marijana Hadzima-Nyarko ◽  
Gordana Pavić
Keyword(s):  
Ground Motions ◽  
Spectral Amplitude ◽  
Eurocode 8 ◽  
Uniform Hazard Spectra ◽  
Study Region ◽  
Spectral Estimates ◽  
Local Soil ◽  
The Impact ◽  
Deep Soils ◽  
The City

The severity of vertical seismic ground motions is often factored into design regulations as a component of their horizontal counterparts. Furthermore, most design codes, including Eurocode 8, ignore the impact of local soil on vertical spectra. This paper investigates vertical pseudo-absolute acceleration spectral estimates, as well as the ratios of spectral estimates for strong motion in vertical and horizontal directions, for low to medium seismicity regions with deep local soil and deep geological sediments beneath the local soil. The case study region encompasses the city of Osijek in Croatia. New regional frequency-dependent empirical scaling equations are derived for the vertical spectra. According to these equations, for a 0.3 s spectral amplitude at deep soils atop deep geological sediments compared to the rock sites, the maximum amplification is 1.48 times. The spectra of vertical components of various real strong motions recorded in the surrounding region are compared to the empirical vertical response spectra. The new empirical equations are used to construct a Uniform Hazard Spectra for Osijek. The ratios of vertical to horizontal Uniform Hazard Spectra are generated, examined, and compared to Eurocode 8 recommendations. All the results show that local soil and deep geology conditions have a significant impact on vertical ground motions. The results also show that for deep soils atop deep geological strata, Eurocode 8 can underestimate the vertical to horizontal spectral ratios by a factor of three for Type 2 spectra while overestimating them by a factor of two for Type 1 spectra.

scholarly journals Accuracy Assessment of Nonlinear Seismic Displacement Demand Predicted by Simplified Methods for the Plateau Range of Design Response Spectra

2019 ◽  
Vol 2019 ◽  
pp. 1-16
Author(s):  
Pierino Lestuzzi ◽  
Lorenzo Diana
Keyword(s):  
Response Spectra ◽  
Strength Reduction ◽  
Nonlinear Time History Analysis ◽  
Eurocode 8 ◽  
Seismic Displacement ◽  
Demand Prediction ◽  
N2 Method ◽  
Displacement Demand ◽  
The Impact ◽  
Reduction Factors

The nonlinear seismic displacement demand prediction for low-period structures, i.e., with an initial fundamental period situated in the plateau of design response spectra, is studied. In Eurocode 8, the computation of seismic displacement demands is essentially based on a simplified method called the N2 method. Alternative approaches using linear computation with increased damping ratio are common in other parts of the world. The accuracy of three methods for seismic displacement demand prediction is carefully examined for the plateau range of Type-1 soil class response spectra of Eurocode 8. The accuracy is assessed through comparing the displacement demand computed using nonlinear time-history analysis (NLTHA) with predictions using simplified methods. The N2 method, a recently proposed optimization of the N2 method, and the Lin and Miranda method are compared. Nonlinear single-degree-of-freedom systems are subjected to several sets of recorded earthquakes that are modified to match design response spectra prescribed by Eurocode 8. The shape of Eurocode 8 response spectra after the plateau is defined by a constant pseudovelocity range (1/T). However, the slope of this declining branch may be specified using precise spectral microzonation investigation. However, the N2 method has been found to be particularly inaccurate with certain microzonation response spectra that are characterized by a gently decreasing branch after the plateau. The present study investigates the impact of the slope of the decreasing branch after the plateau of response spectra on the accuracy of displacement demand predictions. The results show that the accuracy domain of the N2 method is restricted to strength reduction factor values around 3.5. Using the N2 method to predict displacement demands leads to significant overestimations for strength reduction factors smaller than 2.5 and to significant underestimations for strength reduction factors larger than 4. Fortunately, the optimized N2 method leads to accurate results for the whole range of strength reduction factors. For small values of strength reduction factors, up to 2.5, the optimized N2 method and the Lin and Miranda method both provide accurate displacement demand predictions. However, the accuracy of displacement demand prediction strongly depends on the shape of the response spectrum after the plateau. A gently decreasing branch after the plateau affects the accuracy of displacement demand predictions. A threshold value of 0.75 for the exponent of the decreasing branch (1/Tα) after the plateau is proposed. This issue should be considered for the ongoing developments of Eurocode 8.

scholarly journals Comparative study of codes for the seismic design of structures

2012 ◽  
Vol 5 (6) ◽  
pp. 812-819
Author(s):  
S. H. C. Santos ◽  
S. S. Lima ◽  
A. Arai
Keyword(s):  
Seismic Design ◽  
Response Spectra ◽  
Soil Liquefaction ◽  
Eurocode 8 ◽  
South American ◽  
The South ◽  
Seismic Zonation ◽  
Seismic Force ◽  
Western Border ◽  
Definition Of

A general evaluation of some points of the South American seismic codes is presented herein, comparing them among themselves and with the American Standard ASCE/SEI 7/10 and with the European Standard Eurocode 8. The study is focused in design criteria for buildings. The Western border of South America is one of the most seismically active regions of the World. It corresponds to the confluence of the South American and Nazca plates. This region corresponds roughly to the vicinity of the Andes Mountains. This seismicity diminishes in the direction of the comparatively seismically quieter Eastern South American areas. The South American countries located in its Western Border possess standards for seismic design since some decades ago, being the Brazilian Standard for seismic design only recently published. This study is focused in some critical topics: definition of the recurrence periods for establishing the seismic input; definition of the seismic zonation and design ground motion values; definition of the shape of the design response spectra; consideration of soil amplification, soil liquefaction and soil-structure interaction; classification of the structures in different importance levels; definition of the seismic force-resisting systems and respective response modification coefficients; consideration of structural irregularities and definition of the allowable procedures for the seismic analyses. A simple building structure is analyzed considering the criteria of the several standards and obtained results are compared.

scholarly journals Horizontal UHS Amplitudes for Regions with Deep Soil Atop Deep Geological Sediments—An Example of Osijek, Croatia

2021 ◽  
Vol 11 (14) ◽  
pp. 6296
Author(s):  
Borko Đ. Bulajić ◽  
Marijana Hadzima-Nyarko ◽  
Gordana Pavić
Keyword(s):  
Pannonian Basin ◽  
Strong Motion ◽  
Response Spectra ◽  
Eurocode 8 ◽  
Deep Soil ◽  
Regional Seismicity ◽  
South Central ◽  
Local Soil ◽  
Short Period ◽  
Deep Soils

In this paper, we demonstrate how UHS-based seismic microzonation can be applied in low-to-medium seismicity areas with deep local soil and deep geological deposits under the local soil. The case study area surrounds the city of Osijek, Croatia, which is in the south–central region of the Pannonian Basin. New frequency-dependent scaling equations are derived, and the empirical response spectra are compared to the spectra of real strong motions in the surrounding region. Empirical calculations for deep soil atop deep geological strata show a 37% reduction in short-period spectral amplitudes when compared to rock locations. This demonstrates that local soil amplification is mitigated by energy dissipation in deep soils. For vibration periods longer than 0.3 s, spectral amplitudes are being amplified. This amplification goes up to 2.37 times for vibration periods around 0.5 s. UHS spectra for Osijek are computed using regional seismicity estimates, data on local soil and deeper geological surroundings, and newly created regional empirical equations for scaling various spectral amplitudes. UHS amplitudes for Osijek are also compared to the Eurocode 8 spectra for ground type C. The results show that ratios of the maximum UHS amplitudes to PGA values are up to 46% larger than the corresponding 2.5 factor that is recommended by Eurocode 8 for horizontal spectra. The UHS results might be viewed as preliminary for Osijek and regions with similar seismicity and local soil and deep geology conditions. When the number of regional strong-motion records grows many times beyond what it is currently, it will be feasible to properly calibrate the scaling equations, resulting in more reliable and long-term UHS estimations for the area under consideration.

scholarly journals Comparative Study of Codes for Seismic Design of Structures

2013 ◽  
Vol 9 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Sergio Hampshire De C. Santos ◽  
Luca Zanaica ◽  
Carmen Bucur ◽  
Silvio De Souza Lima
Keyword(s):  
Seismic Design ◽  
Model Building ◽  
Seismic Analysis ◽  
Response Spectra ◽  
Soil Conditions ◽  
Seismic Zonation ◽  
Seismic Input ◽  
Local Soil ◽  
Seismic Force ◽  
Definition Of

Abstract This paper presents a comparative evaluation among some international, European and American, seismic design standards. The study considers the criteria for the analysis of conventional (residential and commercial) buildings. The study is focused on some critical topics: definition of the recurrence periods for establishing the seismic input; definition of the seismic zonation and shape of the design response spectra; consideration of local soil conditions; definition of the seismic force-resisting systems and respective response modification coefficients; definition of the allowable procedures for the seismic analysis. A model for a standard reinforced concrete building (“Model Building”) has been developed to permit the comparison among codes. This building has been modelled with two different computer programs, SAP2000 and SOFiSTiK and subjected to seismic input according to the several seismic codes. The obtained results compared are leading to some important conclusions.

scholarly journals An Evaluation Methodology for Interactive Reinforcement Learning with Simulated Users

Biomimetics ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 13
Author(s):  
Adam Bignold ◽  
Francisco Cruz ◽  
Richard Dazeley ◽  
Peter Vamplew ◽  
Cameron Foale
Keyword(s):  
Reinforcement Learning ◽  
Information Source ◽  
Human Interaction ◽  
Evaluation Methodology ◽  
External Information ◽  
Preliminary Evaluation ◽  
Learning Agents ◽  
Learning Agent ◽  
Knowledge Bias ◽  
The Impact

Interactive reinforcement learning methods utilise an external information source to evaluate decisions and accelerate learning. Previous work has shown that human advice could significantly improve learning agents’ performance. When evaluating reinforcement learning algorithms, it is common to repeat experiments as parameters are altered or to gain a sufficient sample size. In this regard, to require human interaction every time an experiment is restarted is undesirable, particularly when the expense in doing so can be considerable. Additionally, reusing the same people for the experiment introduces bias, as they will learn the behaviour of the agent and the dynamics of the environment. This paper presents a methodology for evaluating interactive reinforcement learning agents by employing simulated users. Simulated users allow human knowledge, bias, and interaction to be simulated. The use of simulated users allows the development and testing of reinforcement learning agents, and can provide indicative results of agent performance under defined human constraints. While simulated users are no replacement for actual humans, they do offer an affordable and fast alternative for evaluative assisted agents. We introduce a method for performing a preliminary evaluation utilising simulated users to show how performance changes depending on the type of user assisting the agent. Moreover, we describe how human interaction may be simulated, and present an experiment illustrating the applicability of simulating users in evaluating agent performance when assisted by different types of trainers. Experimental results show that the use of this methodology allows for greater insight into the performance of interactive reinforcement learning agents when advised by different users. The use of simulated users with varying characteristics allows for evaluation of the impact of those characteristics on the behaviour of the learning agent.

scholarly journals Decreased Medical Care During the COVID-19 Pandemic – A Comprehensive Analysis of Radiological Examinations

2021 ◽  
Author(s):  
Annette Aigner ◽  
Bernd Hamm ◽  
Florian Nima Fleckenstein ◽  
Tazio Maleitzke ◽  
Georg Böning ◽  
...  
Keyword(s):  
Medical Care ◽  
Control Period ◽  
Surrogate Marker ◽  
Medical Specialty ◽  
Case Volume ◽  
Medical Specialties ◽  
Key Points ◽  
Depth Analysis ◽  
The Impact ◽  
Radiological Examinations

Objectives As a cross-section discipline within the hospital infrastructure, radiological departments might be able to provide important information regarding the impact of the COVID-19 pandemic on healthcare. The goal of this study was to quantify changes in medical care during the first wave of the pandemic using radiological examinations as a comprehensive surrogate marker and to determine potential future workload. Methods A retrospective analysis of all radiological examinations during the first wave of the pandemic was performed. The number of examinations was compared to time-matched control periods. Furthermore, an in-depth analysis of radiological examinations attributed to various medical specialties was conducted and postponed examinations were extrapolated to calculate additional workload in the near future. Results A total of 596,760 examinations were analyzed. Overall case volumes decreased by an average of 41 % during the shutdown compared to the control period. The most affected radiological modalities were sonography (–54 %), X-ray (–47 %) followed by MRI (–42 %). The most affected medical specialty was trauma and orthopedics (–60 % case volume) followed by general surgery (–49 %). Examination numbers increased during the post-shutdown period leading to a predicted additional workload of up to 22 %. Conclusion This study shows a marked decrease in radiological examinations in total and among several core medical specialties, indicating a significant reduction in medical care during the first COVID-19 shutdown. Key Points: Citation Format

scholarly journals A Whole Virion Vaccine for COVID-19 Produced via a Novel Inactivation Method and Preliminary Demonstration of Efficacy in an Animal Challenge Model

Vaccines ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 340
Author(s):  
Izabela K Ragan ◽  
Lindsay M Hartson ◽  
Taru S Dutt ◽  
Andres Obregon-Henao ◽  
Rachel M Maison ◽  
...  
Keyword(s):  
Vaccine Candidate ◽  
Rapid Development ◽  
Neutralizing Antibody ◽  
Emerging Diseases ◽  
Effective Vaccine ◽  
Preliminary Evaluation ◽  
Sequencing Data ◽  
Post Challenge ◽  
Vaccine Candidates ◽  
The Impact

The COVID-19 pandemic has generated intense interest in the rapid development and evaluation of vaccine candidates for this disease and other emerging diseases. Several novel methods for preparing vaccine candidates are currently undergoing clinical evaluation in response to the urgent need to prevent the spread of COVID-19. In many cases, these methods rely on new approaches for vaccine production and immune stimulation. We report on the use of a novel method (SolaVAX) for production of an inactivated vaccine candidate and the testing of that candidate in a hamster animal model for its ability to prevent infection upon challenge with SARS-CoV-2 virus. The studies employed in this work included an evaluation of the levels of neutralizing antibody produced post-vaccination, levels of specific antibody sub-types to RBD and spike protein that were generated, evaluation of viral shedding post-challenge, flow cytometric and single cell sequencing data on cellular fractions and histopathological evaluation of tissues post-challenge. The results from this preliminary evaluation provide insight into the immunological responses occurring as a result of vaccination with the proposed vaccine candidate and the impact that adjuvant formulations, specifically developed to promote Th1 type immune responses, have on vaccine efficacy and protection against infection following challenge with live SARS-CoV-2. This data may have utility in the development of effective vaccine candidates broadly. Furthermore, the results of this preliminary evaluation suggest that preparation of a whole virion vaccine for COVID-19 using this specific photochemical method may have potential utility in the preparation of one such vaccine candidate.

scholarly journals Impact of the first COVID-19 shutdown on patient volumes and surgical procedures of a Level I trauma center

2021 ◽  
Author(s):  
Carolin A. Kreis ◽  
Birte Ortmann ◽  
Moritz Freistuehler ◽  
René Hartensuer ◽  
Hugo Van Aken ◽  
...  
Keyword(s):  
Surgical Procedures ◽  
Trauma Center ◽  
Control Period ◽  
Open Fractures ◽  
Injury Patterns ◽  
Emergency Patient ◽  
Emergency Operations ◽  
Incidence Proportion ◽  
Level I ◽  
The Impact

Abstract Purpose In Dec 2019, COVID-19 was first recognized and led to a worldwide pandemic. The German government implemented a shutdown in Mar 2020, affecting outpatient and hospital care. The aim of the present article was to evaluate the impact of the COVID-19 shutdown on patient volumes and surgical procedures of a Level I trauma center in Germany. Methods All emergency patients were recorded retrospectively during the shutdown and compared to a calendar-matched control period (CTRL). Total emergency patient contacts including trauma mechanisms, injury patterns and operation numbers were recorded including absolute numbers, incidence proportions and risk ratios. Results During the shutdown period, we observed a decrease of emergency patient cases (417) compared to CTRL (575), a decrease of elective cases (42 vs. 13) and of the total number of operations (397 vs. 325). Incidence proportions of emergency operations increased from 8.2 to 12.2% (shutdown) and elective surgical cases decreased (11.1 vs. 4.3%). As we observed a decrease for most trauma mechanisms and injury patterns, we found an increasing incidence proportion for severe open fractures. Household-related injuries were reported with an increasing incidence proportion from 26.8 to 47.5% (shutdown). We found an increasing tendency of trauma and injuries related to psychological disorders. Conclusion This analysis shows a decrease of total patient numbers in an emergency department of a Level I trauma center and a decrease of the total number of operations during the shutdown period. Concurrently, we observed an increase of severe open fractures and emergency operations. Furthermore, trauma mechanism changed with less traffic, work and sports-related accidents.

P1574EFFECTS OF BRAZILIAN GREEN PROPOLIS EXTRACT (EPP-AF) ON INFLAMMATION IN HEMODIALYSIS PATIENTS

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Marcelo Silveira ◽  
Flavio Teles ◽  
Erica Melo ◽  
Valeria Borges ◽  
Filipe Miranda ◽  
...  
Keyword(s):  
Control Period ◽  
Prospective Trial ◽  
Hemodialysis Patients ◽  
Intermittent Hemodialysis ◽  
Plant Materials ◽  
Propolis Extract ◽  
End Point ◽  
Number Of Patients ◽  
The Impact ◽  
Brazilian Green Propolis

Abstract Background and Aims End-stage chronic kidney disease is associated with the condition of chronic inflammation, impacting increased cardiovascular mortality in this specific population. Patients on hemodialysis are known to be predisposed to several factors that predispose to inflammation: dialysis membranes, central venous catheters, oxidative stress, fluid overload, sodium overload, uraemic toxins. Propolis, a natural resin produced by bees from plant materials, has anti-inflammatory, immunomodulatory, and anti-oxidant properties. The aim of this study was to evaluate the impact of Brazilian green propolis extract on inflammation in hemodialysis patients. Here we present preliminary results of the trial NCT04072341. Method We performed a prospective trial, open-label 9-week crossover study examining the effect of Brazilian green propolis (250mg/day, in capsules) on inflammation in hemodialysis patients. We included patients over 18 years, under intermittent hemodialysis (thrice per week), on hemodialysis for at least 1 month and until now 37 patients were included. We excluded pregnant women, cancer carried and patients who developed infection or underwent any surgical procedure during the study period. Each period was 4 weeks in duration with a 1-week washout period in between. The primary end point was change in serum level of high-sensitivity c-reactive protein (HsCRP). Secondary end point evaluated the safety of propolis use in hemodialysis patients. Results Their mean age was 58.6 ± 15.2 years (mean ± SD), and 22 (59.4%) were men. The proportion of patients with hypertension was 14 (37.8%) and diabetes was 9 (24.3%). The number of patients using arteriovenous fistula were 26 (70.2%). The HsCRP presented (mean ± SE) 5.31 ± 1.02 mg/L at baseline, 4.26 ± 0.76 mg/L after propolis period and 4.56 ± 1.32 mg/L in control period, p = 0.0042. Safety parameters were analyzed such as amylase, aspartate aminotransferase (AST) and creatine phosphokinase (CPK); there was no difference between them before and after the use of propolis. None of the participants reported any adverse effects or allergic reactions during the treatment. Conclusion Patients on hemodialysis have an increased inflammatory state. For the best of our knowledge it was the first clinical trial who demonstrated the safety of propolis in hemodialysis patients. Brazilian green propolis demonstrated a tendency to reduce inflammation in these patients.

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