In this paper,the effects of foundation damage and water-level change on vibration characteristics of gravity-type caisson structure are examined by analyzing modal parameters extracted from output-only information.To...In this paper,the effects of foundation damage and water-level change on vibration characteristics of gravity-type caisson structure are examined by analyzing modal parameters extracted from output-only information.To achieve the objective,the following approaches are implemented.Firstly,vibration response analysis methods are selected to estimate power spectral density and modal parameters such as natural frequency,damping ratio and mode shape of a lab-scale caisson structural system.Secondly,vibration tests on the lab-scale caisson system are performed under a series of test scenarios which include three water-level changes and three damage levels.Thirdly,experimental modal parameters corresponding to the damaging cases as well as the water level cases are extracted by frequency domain decomposition method and stochastic subspace identification method.Finally,the effects of the water-level variation and foundation damage on the extracted modal parameters are examined to assess the feasibility of the vibration-based damage detection in gravity-type caisson structures under water-level uncertainty.展开更多
Purpose： As trauma is a public health problem, different programs have been designed to prevent in- juries. The aim of this study was to evaluate the effectiveness of an educational model that measures the adolescent...Purpose： As trauma is a public health problem, different programs have been designed to prevent in- juries. The aim of this study was to evaluate the effectiveness of an educational model that measures the adolescents＇ attitudes towards the rules of road safety, alcohol and road accidents in Colombia. Methods： A pedagogical model evaluating the effect of road safety education and adolescents＇ attitudes towards and experiences of alcohol and road accidents in Colombia was created. After the education concluded, this educational process is analyzed by its impact on adolescents＇ behavior. The educational program included 160 adolescents with the mean age being 1Z5 years. Results： The test results indicated that before the educational program 80g of adolescents did not use a safety element when driving, while after the educational program the percentage of no helmet use among adolescents decreased from 72.5% to 24.3% （p = 0.0001 ） and driving a vehicle under the state of drunkenness from 49.3% to 8.1% （p = 0.0001）. Conclusion： An educational model aimed at preventing injuries caused by traffic accidents is shown to be effective in generating changes in adolescents＇ customs of and attitudes towards alcohol and road safety standards in Colombia.展开更多
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry ofEducation,Science and Technology(Grant no.NRF-2013R1A1A2A10012040)the financial support of the project Development of Inspection Equipment Technology for Harbor Facilities funded by Korea Ministry of Land,Transportation,and Maritime Affairs
文摘In this paper,the effects of foundation damage and water-level change on vibration characteristics of gravity-type caisson structure are examined by analyzing modal parameters extracted from output-only information.To achieve the objective,the following approaches are implemented.Firstly,vibration response analysis methods are selected to estimate power spectral density and modal parameters such as natural frequency,damping ratio and mode shape of a lab-scale caisson structural system.Secondly,vibration tests on the lab-scale caisson system are performed under a series of test scenarios which include three water-level changes and three damage levels.Thirdly,experimental modal parameters corresponding to the damaging cases as well as the water level cases are extracted by frequency domain decomposition method and stochastic subspace identification method.Finally,the effects of the water-level variation and foundation damage on the extracted modal parameters are examined to assess the feasibility of the vibration-based damage detection in gravity-type caisson structures under water-level uncertainty.
文摘Purpose： As trauma is a public health problem, different programs have been designed to prevent in- juries. The aim of this study was to evaluate the effectiveness of an educational model that measures the adolescents＇ attitudes towards the rules of road safety, alcohol and road accidents in Colombia. Methods： A pedagogical model evaluating the effect of road safety education and adolescents＇ attitudes towards and experiences of alcohol and road accidents in Colombia was created. After the education concluded, this educational process is analyzed by its impact on adolescents＇ behavior. The educational program included 160 adolescents with the mean age being 1Z5 years. Results： The test results indicated that before the educational program 80g of adolescents did not use a safety element when driving, while after the educational program the percentage of no helmet use among adolescents decreased from 72.5% to 24.3% （p = 0.0001 ） and driving a vehicle under the state of drunkenness from 49.3% to 8.1% （p = 0.0001）. Conclusion： An educational model aimed at preventing injuries caused by traffic accidents is shown to be effective in generating changes in adolescents＇ customs of and attitudes towards alcohol and road safety standards in Colombia.
