Collapse probability and resistance factor calibration of 2D steel frames under gravity loads

Abstract The current advanced analysis techniques for steel frames generally use structural analyses with geometric and material nonlinearities to capture the collapse strength of the steel frame. Unfortunately, the true strength of a steel frame cannot be predicted with accuracy because of the uncertainties of the most significant design variables. Building codes of steel structures apply a resistance factor to account for the uncertainties present in the design variables and thus ensure a target level of structural reliability. This article examines the reliability of planar steel frames subject to gravitational loads by advanced structural analysis (second-order inelastic analysis). To calculate the collapse probability of planar steel frames, we utilized the first-order reliability method (FORM). The advanced analyses were performed using the program MASTAN2 and considered the geometric nonlinearities and inelasticity of the steel. The collapse probabilities of planar steel frames were evaluated and the adequacy of the resistance factor applied was discussed. The current inelastic design procedure of ANSI 360 reduces the yield strength and stiffness of all members by a factor of 0.90. Thus, the present study suggests that the adopted resistance factor must be equal to 0.85 for the target reliability index equal to 3.0, or it must be equal to 0.69 for the target reliability index equal to 3.8

Vibration behavior of thin-walled steel members subjected to uniform bending

Abstract This article reports the results of an investigation on the effects of internal moments on the vibration behavior of thin-walled steel members. The analyses are based on the Generalized Beam Theory (GBT), a thin-walled bar theory accounting for cross-section in-plane deformations - its main distinctive feature is the representation of the member deformed configuration by means of a linear combination of cross-section deformation modes, multiplied by their longitudinal amplitude functions. The study concerns a simply supported T-section (with unequal flanges) members exhibiting a wide range of lengths and subjected to uniform internal moment diagrams - their magnitudes are specified as percentages of the corresponding critical buckling values. After providing a brief overview of the main concepts and procedures involved in performing a GBT-based structural analysis, the vibration behavior of load-free and loaded T-section members is addressed - the influence of the applied loadings is assessed in terms of (i) the fundamental frequency difference and (ii) the change in the corresponding vibration mode shape. For validation purposes, some GBT results are compared with values yielded by shell finite element analysis performed in the code ABAQUS (Simulia, 2008)

Fatal outcome of chikungunya virus infection in Brazil

Federal University of Ceará. Fortaleza, CE, Brazil / Central Public Health Laboratory of Ceará State. Fortaleza, CE, Brazil.University of São Paulo. Virology Research Center. Ribeirão Preto, SP, Brazil.Federal University of Ceará. Fortaleza, CE, Brazil.University of Oxford. Department of Zoology. oxford, United Kingdom.University of São Paulo. Virology Research Center. Ribeirão Preto, SP, Brazil.University of Oxford. Department of Zoology. oxford, United Kingdom / Gorgas Memorial Institute of Health Studies. Department of Research in Virology and Biotechnology. Panama City, Panama.Central Public Health Laboratory of Ceará State. Fortaleza, CE, Brazil.Central Public Health Laboratory of Ceará State. Fortaleza, CE, Brazil / Centro Universitário Christus. Faculdade de Medicina. Fortaleza, CE, Brazil.Central Public Health Laboratory of Ceará State. Fortaleza, CE, Brazil.Federal University of Ceará. Fortaleza, CE, Brazil.State Health Secretariat of Ceará. Death Verification Service Dr Rocha Furtado. Fortaleza, CE, Brazil.Federal University of Ceará. Fortaleza, CE, Brazil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Federal University of Ceará. Fortaleza, CE, Brazil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Centro Universitário Christus. Faculdade de Medicina. Fortaleza, CE, Brazil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Centro Universitário Christus. Faculdade de Medicina. Fortaleza, CE, Brazil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Centro Universitário Christus. Faculdade de Medicina. Fortaleza, CE, Brazil.Centro Universitário Christus. Faculdade de Medicina. Fortaleza, CE, Brazil.Centro Universitário Christus. Faculdade de Medicina. Fortaleza, CE, Brazil.Federal University of Ceará. Fortaleza, CE, Brazil.Universidade Federal de Minas Gerais. Belo Horizonte, MG, Brazil.Universidade Federal de Minas Gerais. Belo Horizonte, MG, Brazil / Ministry of Health. Brasilia, DF, Brazil.Ministry of Health. Brasilia, DF, Brazil.Ministry of Health. Brasilia, DF, Brazil.Ministry of Health. Brasilia, DF, Brazil.Faculdade de Medicina São Leopoldo Mandic. Campinas, SP, Brazil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.University of Oxford. Department of Zoology. Oxford, United Kingdom.University of São Paulo. Virology Research Center. Ribeirão Preto, SP, Brazil.University of Oxford. Department of Zoology. Oxford, United Kingdom / Imperial College London. Department of Infectious Disease Epidemiology. London, United Kingdom.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Federal University of Ceará. Fortaleza, CE, Brazil.Federal University of Ceará. Fortaleza, CE, Brazil / Oswaldo Cruz Foundation - Branch Ceará. Fortaleza, CE, Brazil.BACKGROUND: Chikungunya virus (CHIKV) emerged in the Americas in 2013 and has caused approximately 2.1 million cases and >600 deaths. A retrospective investigation was undertaken to describe clinical, epidemiological, and viral genomic features associated with deaths caused by CHIKV in Ceará state, northeast Brazil. METHODS: Sera, cerebrospinal fluid (CSF), and tissue samples from 100 fatal cases with suspected arbovirus infection were tested for CHIKV, dengue virus (DENV), and Zika virus (ZIKV). Clinical, epidemiological, and death reports were obtained for patients with confirmed CHIKV infection. Logistic regression analysis was undertaken to identify independent factors associated with risk of death during CHIKV infection. Phylogenetic analysis was conducted using whole genomes from a subset of cases. RESULTS: Sixty-eight fatal cases had CHIKV infection confirmed by reverse-transcription quantitative polymerase chain reaction (52.9%), viral antigen (41.1%), and/or specific immunoglobulin M (63.2%). Co-detection of CHIKV with DENV was found in 22% of fatal cases, ZIKV in 2.9%, and DENV and ZIKV in 1.5%. A total of 39 CHIKV deaths presented with neurological signs and symptoms, and CHIKV-RNA was found in the CSF of 92.3% of these patients. Fatal outcomes were associated with irreversible multiple organ dysfunction syndrome. Patients with diabetes appear to die at a higher frequency during the subacute phase. Genetic analysis showed circulation of 2 CHIKV East-Central-South African (ECSA) lineages in Ceará and revealed no unique virus genomic mutation associated with fatal outcome. CONCLUSIONS: The investigation of the largest cross-sectional cohort of CHIKV deaths to date reveals that CHIKV-ECSA strains can cause death in individuals from both risk and nonrisk groups, including young adults. © The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America