Engineering structures may be exposed to one or more extreme hazards during their life-cycles.Current structural design specifications usually treat multiple hazards separately in designing structures and there is a l...Engineering structures may be exposed to one or more extreme hazards during their life-cycles.Current structural design specifications usually treat multiple hazards separately in designing structures and there is a limited probabilistic basis on extreme load combinations.Additionally,the performance of engineering structures will be deteriorated by the aggressive environments during their service periods,such as chloride attack,concrete carbonation,and wind-induced fatigue.This study presents a probabilistic methodology to assess the time-dependent failure probability of RC bridges with chloride-induced corrosion under the multiple hazards of earthquakes and strong winds.The loss of cross-section area of reinforcements and the reduction in strength of reinforcing steel and concrete cover induced by the chloride attack are considered.Moreover,the Poisson model is employed to obtain the occurrence probabilities of the individual and concurrent earthquake and strong wind events.The convolution integral is used to determine the joint probability distribution of combined load effects under simultaneous earthquakes and strong winds.Numerical results indicate that the structural failure probability under multiple hazards increases significantly during the bridge′s life-cycle due to the chloride corrosion effect.The contribution of each hazard event on the total structural failure probability varies with time.Thus,neglecting the combined influences of multiple hazards and chloride-induced corrosion may bring erroneous predictions in failure probability estimates of RC bridges.展开更多
This study is an attempt to point out the different types of natural hazards in Sudur Paschim province of Nepal where environmental degradation processes such as deforestation,desertification,biodiversity loss,soil cr...This study is an attempt to point out the different types of natural hazards in Sudur Paschim province of Nepal where environmental degradation processes such as deforestation,desertification,biodiversity loss,soil crisp and watershed degradation are rising trends.Using participatory method multi hazard prone areas were identified with type and intensity.Multi criteria evaluation method was applied to prioritize replicable actions with location-specific innovative practices and their legitimization for integrating local and indigenous knowledge into mainstream education,science and policy with a view to incorporate local and indigenous knowledge as live science in disaster and climate change education.Findings of the study reveal that varieties of natural hazards in combination with social factors such as poverty,conflict and inequality have resulted frequent disasters and social vulnerabilities in many parts of the province.Traditionally,indigenous and local people have responded threats of multi hazards by using their traditional knowledge and skills which has evolved over generations,and continue to adapt to future changes.These traditional,often faith-based,beliefs and practices were found to use as the key to their resilience in the face of natural hazards.However,many communities have been lost their knowledge as the elderly die without transferring it to younger members.Behind this proper educational policy and strategic development plans have not been implemented to cope local/indigenous knowledge into practices.Findings of the study indicate that indigenous and local knowledge is a precious province resource that can support the process of disaster prevention,preparedness and response in cost-effective disaster risk reduction.Therefore,policy framework has to prime focus to integrate indigenous and local knowledge,wisdom and skills into mainstream educational programs in order to transfer science into policy and education(words)into practice.展开更多
A uniform and comprehensive classification system, often referred to as taxonomy, is fundamental for the characterization of building portfolios for natural hazard risk assessment. A building taxonomy characterizes as...A uniform and comprehensive classification system, often referred to as taxonomy, is fundamental for the characterization of building portfolios for natural hazard risk assessment. A building taxonomy characterizes assets according to attributes that can influence the likelihood of damage due to the effects of natural hazards.Within the scope of the Global Earthquake Model(GEM)initiative, a building taxonomy(GEM Building Taxonomy V2.0) was developed with the goal of classifying buildings according to their seismic vulnerability. This taxonomy contained 13 building attributes, including the main material of construction, lateral load-resisting system, date of construction and number of stories. Since its release in2012, the taxonomy has been used by hundreds of experts working on exposure and risk modeling efforts. These applications allowed the identification of several limitations, which led to the improvement and expansion of this taxonomy into a new classification system compatible with multi-hazard risk assessment. This expanded taxonomy(named GED4ALL) includes more attributes and several details relevant for buildings exposed to natural hazards beyond earthquakes. GED4ALL has been applied in several international initiatives, enabling the identification of the most common building classes in the world, and facilitating compatibility between exposure models and databases of vulnerability and damage databases.展开更多
基金Supported by:Fundamental Research Funds for the Central Universities under Grant No.2021QN1022。
文摘Engineering structures may be exposed to one or more extreme hazards during their life-cycles.Current structural design specifications usually treat multiple hazards separately in designing structures and there is a limited probabilistic basis on extreme load combinations.Additionally,the performance of engineering structures will be deteriorated by the aggressive environments during their service periods,such as chloride attack,concrete carbonation,and wind-induced fatigue.This study presents a probabilistic methodology to assess the time-dependent failure probability of RC bridges with chloride-induced corrosion under the multiple hazards of earthquakes and strong winds.The loss of cross-section area of reinforcements and the reduction in strength of reinforcing steel and concrete cover induced by the chloride attack are considered.Moreover,the Poisson model is employed to obtain the occurrence probabilities of the individual and concurrent earthquake and strong wind events.The convolution integral is used to determine the joint probability distribution of combined load effects under simultaneous earthquakes and strong winds.Numerical results indicate that the structural failure probability under multiple hazards increases significantly during the bridge′s life-cycle due to the chloride corrosion effect.The contribution of each hazard event on the total structural failure probability varies with time.Thus,neglecting the combined influences of multiple hazards and chloride-induced corrosion may bring erroneous predictions in failure probability estimates of RC bridges.
文摘This study is an attempt to point out the different types of natural hazards in Sudur Paschim province of Nepal where environmental degradation processes such as deforestation,desertification,biodiversity loss,soil crisp and watershed degradation are rising trends.Using participatory method multi hazard prone areas were identified with type and intensity.Multi criteria evaluation method was applied to prioritize replicable actions with location-specific innovative practices and their legitimization for integrating local and indigenous knowledge into mainstream education,science and policy with a view to incorporate local and indigenous knowledge as live science in disaster and climate change education.Findings of the study reveal that varieties of natural hazards in combination with social factors such as poverty,conflict and inequality have resulted frequent disasters and social vulnerabilities in many parts of the province.Traditionally,indigenous and local people have responded threats of multi hazards by using their traditional knowledge and skills which has evolved over generations,and continue to adapt to future changes.These traditional,often faith-based,beliefs and practices were found to use as the key to their resilience in the face of natural hazards.However,many communities have been lost their knowledge as the elderly die without transferring it to younger members.Behind this proper educational policy and strategic development plans have not been implemented to cope local/indigenous knowledge into practices.Findings of the study indicate that indigenous and local knowledge is a precious province resource that can support the process of disaster prevention,preparedness and response in cost-effective disaster risk reduction.Therefore,policy framework has to prime focus to integrate indigenous and local knowledge,wisdom and skills into mainstream educational programs in order to transfer science into policy and education(words)into practice.
文摘A uniform and comprehensive classification system, often referred to as taxonomy, is fundamental for the characterization of building portfolios for natural hazard risk assessment. A building taxonomy characterizes assets according to attributes that can influence the likelihood of damage due to the effects of natural hazards.Within the scope of the Global Earthquake Model(GEM)initiative, a building taxonomy(GEM Building Taxonomy V2.0) was developed with the goal of classifying buildings according to their seismic vulnerability. This taxonomy contained 13 building attributes, including the main material of construction, lateral load-resisting system, date of construction and number of stories. Since its release in2012, the taxonomy has been used by hundreds of experts working on exposure and risk modeling efforts. These applications allowed the identification of several limitations, which led to the improvement and expansion of this taxonomy into a new classification system compatible with multi-hazard risk assessment. This expanded taxonomy(named GED4ALL) includes more attributes and several details relevant for buildings exposed to natural hazards beyond earthquakes. GED4ALL has been applied in several international initiatives, enabling the identification of the most common building classes in the world, and facilitating compatibility between exposure models and databases of vulnerability and damage databases.