On the effectiveness of rotational friction hinge damper to control responses of multi-span simply supported bridge to non-uniform ground motions

Base isolation techniques have been extensively used to improve the seismic performance of the bridge structures. The decoupling of the bridge decks from the piers and abutments using rubber isolator could result in significant reduction in seismic forces transmitted to the bridge substructures. However, the isolation devices could also increase the deck displacement and thus enhance the possibility of pounding and unseating damage of bridge decks. Moreover, previous investigations have shown that pounding and unseating damages on isolated bridges exacerbate due to the spatial variation in earthquake ground motions. Recent earthquakes revealed that isolation bearing could also be damaged due to the excessive movements of decks during large earthquake events. This study proposes the use of rotational friction hinge dampers to mitigate the damages that could be induced by large displacement of bridge decks, particularly focusing on pounding and unseating damages and bearing damages. The device is capable of providing large hysteretic damping and the cost of installing the devices is relatively economical. This article presents numerical investigations on the effectiveness of these devices on a typical Nepalese simply supported bridge subjected to spatially varying ground motions. The results indicate that rotational friction hinge dampers are very effective in mitigating the relative displacement and pounding force, as well as controlling the bearing deformation and pier drift. It is also revealed that the effectiveness of the device is not significantly affected by small changes in the slip forces; thus, small variations in the optimum slip forces during the lifetime of the bridge do not warrant any adjustment or replacement of the device

Aparelho de amplificação sonora individual: melhora a sensação de zumbido? Hearing aid: does it reduce the sensation of tinnitus?

OBJETIVO: observar se o uso da amplificação sonora além de garantir melhora na inteligibilidade de fala pode proporcionar alívio na sensação de zumbido. MÉTODOS: participaram do presente estudo 21 indivíduos, usuários de aparelho de amplificação sonora individual (AASI) que referiam sensação de zumbido, além da perda auditiva sensorioneural, sendo 13 (61,9%) indivíduos do sexo feminino e oito (38,1%) do sexo masculino. A idade dos participantes variou entre 35 a 88 anos, com idade média de 61 anos. Para a avaliação dos participantes foi utilizado um questionário específico. Os dados foram analisados por meio de análise estatística descritiva e para tanto foram utilizados os testes não paramétricos: qui-quadrado e Kruskal-Wallis H. RESULTADOS: Entre os 21 participantes, 17 (80,9%) apresentaram melhora do zumbido, enquanto quatro (19,1%) referiram que o aparelho de amplificação não gerou nenhum efeito sobre o sintoma apresentado. CONCLUSÃO: este estudo verificou que a utilização do AASI reduziu imediatamente a sensação de zumbido apresentada na população estudada.<br>PURPOSE: to observe if the use of hearing aid may provide relief in tinnitus sensation besides guarantying the improvement of speech intelligibility. METHODS: a sample was made up by 21 hearing aid users and a specific questionnaire was used for the evaluation of the participants. The ages ranged from 35 to 88-year old, with an average of 61-year old. The tinnitus sensation was mentioned by 13 (61.9%) female beings and eight (38.1%) male beings beyond sensory neural hearing loss. The results were obtained through a descriptive statistical analysis, and furthermore, non-parametric tests were used, such as chi-square and Kruskal-Wallis H. RESULTS: among the participants 17 (80.9%) showed recovery from tinnitus, while four (19.1%) said that the hearing aid device did not cause any effect on the evidenced symptoms. CONCLUSION: this study found out that the usage of the hearing aid reduced promptly the sensation of tinnitus in the studied subjects