Dynamic Behavior of Slender Structures on Their Prestressed Foundations

A non-destructive vibratory testing, using impulsive tension slacking has been devised for the quality and safety control of overhead line towers. Several structural control experiments have been conducted on four-legged towers resting on three types of foundations: concrete stepped or pedestal blocks, steel piles and prestressed foundations. Experimental results have given significant vibratory signatures in close connection with the geotechnical response characteristics of both such slender structures and their foundations. The control of foundation mechanical behavior may be very useful in cases of earthquake resistant construction and design. This paper presents some significant results of the test program

Energy-Absorbing Ability of Texsol

Texsol is a 30 soil-fiber composite, obtained using a technique of soil reinforcement by incorporation of continuous textile fibers. The overall mechanical properties of Texsol result therefore from those of its components: soil and fibers. An experimental approach has been carried out in order to grasp the basic aspects of the stress-strain response of Texsol subjected to monotonic, cyclic and vibratory loadings. The study confirms that the application of Texsol to earthquake resistant earthworks and traffic structures could be of great interest and particularly suitable as shown by its ductility and energy-absorbing capacities that are readily evidenced by the laboratory conventional tests

Seasonal association between ambient ozone and hospital admission for respiratory diseases in Hanoi, Vietnam

BackgroundMany studies have indicated the detrimental effect of ambient ozone to respiratory health in different countries. The levels of ozone in Hanoi, Vietnam are frequently above the WHO guideline but very few studies on the effects of ambient ozone on human health have been conducted in this location. This study aimed to examine the effects of ozone on hospital admission for respiratory diseases in Hanoi, by diseases, ages and seasons.MethodsHospital admissions, air pollutants and meteorological data were collected from January 2010 to June 2014. We used generalized linear models and distributed lag linear model to assess the association. In addition to full year analysis, we conducted restricted analysis of the data for two summer (from June-August) and winter (from December-February) seasons and grouped hospital admissions by diseases and ages (all ages, children 0 to 5 years and elderly >65 years). The delayed effect of ozone was assessed using lags of up to 5 days.ResultsOzone has a stronger effect on the risk of hospital admission for respiratory diseases and wheeze-associated disorders in the winter. For respiratory diseases, children were affected by ozone more than other age groups in both winter and summer. Each increase of 10 mu g/m(3) of ozone is associated with an increase of 6.2% risk of admission for respiratory disease among children in the winter and 1.2% in the summer. For wheeze-associated disorders, the elderly group seemed to be more affected by ozone in full year and winter but no significant association was found between ozone and admission for wheeze-associated diseases in any age group.ConclusionsOzone is a risk factor for respiratory admission, especially amongst children under 5 years old in Hanoi, and ozone has a stronger effect in the winter than in the summer in this city

Air pollution and risk of respiratory and cardiovascular hospitalizations in the most populous city in Vietnam

Air pollution has become an alarming issue in Vietnam recently; however, there was only one study so far on the effects of ambient air pollution on population health. Our study aimed to investigate the short-term effects of air pollutants including PM, NO, SO, and O on respiratory and cardiovascular hospitalizations in Ho Chi Minh City (HCMC), the largest city in Vietnam. Data on hospitalization from the two largest hospitals in HCMC and daily records of PM, NO, SO, O and meteorological data were collected from February 2004 to December 2007. A time-series regression analysis with distributed lag model was applied for data analysis. Changes in levels of NO and PM were strongly associated with hospital admissions for both respiratory and cardiovascular diseases (CVD); whereas levels of SO were only moderately associated with respiratory and CVD hospital admissions and O concentration was not associated with any of them. For a 10 μg/m increase of each air pollutant, the risk of respiratory admissions increased from 0.7% to 8% while the risk of CVD admissions increased from 0.5% to 4%. Females were found to be more sensitive than males to exposure to air pollutants in regard to respiratory diseases. In regard to CVD, females (RR, 1.04, 95% CI, 1.01-1.07) had a slightly higher risk of admissions than males (RR, 1.03, 95% CI, 1-1.06) to exposure to NO. In contrast, males (RR, 1.007, 95%CI, 1-1.01) had a higher risk of admission than females (RR, 1.004, 95%CI, 1.001-1.007) to exposure to PM. People in the age group of 5-65 year-olds had a slightly higher risk of admissions caused by air pollutants than the elderly (65+ years old) except for a significant effect of PM on the risk of cardiovascular admissions was found for the elderly only